Searching \ for '[EE]: Bulb Life -- Burned out bulb resurected' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=bulb+life+burned
Search entire site for: 'Bulb Life -- Burned out bulb resurected'.

Exact match. Not showing close matches.
PICList Thread
'[EE]: Bulb Life -- Burned out bulb resurected'
2001\07\16@125750 by Robert E. Griffith

flavicon
face
I have been having a problem with the light fixture in my kitchen going
through bulbs fast (bulbs lasting about a month). This fixture uses the more
expensive, large diameter bulbs.  When the last one went out, I did not
replace it right away.  Several days later, it came back to life!

Since then, it has gone out several times (for 2-7 days) but has, so far,
always come back to life.

I have measured the voltage in the socket during one of the bulb's dead
periods and verified that there is power in the socket (117v).

I imagine that somewhere in the bulb is an intermittent short.  The room is
air conditioned so temp does not vary that much (except when the bulb is
on:)

Another strange thing:  Three times now, when other bulbs have gone out in
this fixture, the glass bulb separates from the metal socket while the light
is on and drops to the table below!

So I guess my question is "Should I be concerned that this fixture is
haunted?".  Should I call Bill? (Maurry - not Gates)

--BobG

{Original Message removed}

2001\07\16@131819 by Don Hyde

flavicon
face
I would guess that the fixture is trapping heat from the bulb and
overheating it.

{Quote hidden}

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@134640 by Jim

flavicon
face
A loose white wire (neutral) will make the bulb go out fast...


----- Original Message -----
From: "Don Hyde" <DonHspamspam_OUTAXONN.COM>
To: <@spam@PICLISTKILLspamspamMITVMA.MIT.EDU>
Sent: Monday, July 16, 2001 12:13 PM
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected


> I would guess that the fixture is trapping heat from the bulb and
> overheating it.
>
> > {Original Message removed}

2001\07\16@141020 by Robert E. Griffith

flavicon
face
What does the loose neutral do to make the bulb burn out faster?

--BobG

-----Original Message-----
From: pic microcontroller discussion list [KILLspamPICLISTKILLspamspamMITVMA.MIT.EDU]On
Behalf Of Jim
Sent: Monday, July 16, 2001 1:43 PM
To: RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected

A loose white wire (neutral) will make the bulb go out fast...


----- Original Message -----
From: "Don Hyde" <spamBeGoneDonHspamBeGonespamAXONN.COM>
To: <TakeThisOuTPICLISTEraseMEspamspam_OUTMITVMA.MIT.EDU>
Sent: Monday, July 16, 2001 12:13 PM
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected


{Quote hidden}

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@144433 by Spehro Pefhany
picon face
At 01:58 PM 7/16/01 -0400, you wrote:
>What does the loose neutral do to make the bulb burn out faster?

Normal wiring in US and Canadian residences looks like this..

120VAC
o-------x    <----------x
       |               |
  [100W bulb]          |
N       |               |
o--//---x              240VAC
       |               |
   [500W load]         |
       |               |
o-------x    <----------x
120VAC


See what happens to the 100W bulb if the neutral connection is flakey?

Best regards,
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
RemoveMEspeffTakeThisOuTspamspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@150548 by Robert E. Griffith

flavicon
face
I am embarrassed to say that I do not get it.  What's the 500w load in your
diagram? In your scenario, is the faulty neutral at the breaker box or at
the lamp?

Every outlet/lamp fixture in my house has 3 wires - what I typically think
of as 'line', 'ground', and 'neutral'.  Ground and neutral are at the same
potential and 'line' is +-120vac.  I think of ground as an alternate return
path to ground in case the line is accidentally exposed. I have never quite
understood why ground and neutral should be electrically isolated.

So you are saying that with a faulty neutral, a 120vac appliance with see
240vac?

--BobG

{Original Message removed}

2001\07\16@151407 by Marc Reinig

flavicon
face
Sounds like you have recessed cans and Halogen spot or floods.  First check
with the manufacturer to verify that the bulbs you are using can be used in
that fixture.  If the glass is separating from the metal fixture, it sounds
like the bulb is not appropriate for the socket in some way.  Most of the
recessed cans have a thermal shutoff.  It sounds like yours is tripping.
This is a good sign that there is something wrong with your bulb/can
combination.  If you are using the large bulbs, then it might be possible
that you are either using too high a wattage, a halogen bulb where you
shouldn't, or a bulb that is physically too large to allow the correct
amount of air circulation to keep the lamp cool.

Marc Reinig
System Solutions


{Original Message removed}

2001\07\16@153200 by Robert E. Griffith

flavicon
face
Thanks for the suggestions.  Here are some facts:

* The bulbs are incandescent, not halogens.
* The fixture is hanging from the ceiling, 3 bulbs, each with a metal
reflector above it - looks like plenty of ventilation to me.
* Each socket is rated for 100w.
* All three bulbs that separated were 60w.
* We have used 60w and 100w bulbs - failure rate is about the same.
* The mysterious off again / on again bulb is 100w.
* Thermal shutoff cannot explain mysterious bulb because it will not light
even when fixture has not been used for hours and I measured the voltage in
its socket while it was not working.

--BobG

{Original Message removed}

2001\07\16@154838 by Martin Baker

flavicon
face
I may not have a clue, but my guess would be that the problem is
mechanical. I would suggest swapping one of the sockets with a standard
replacement from a hardware store..

There are several possible issues, the most likely of which is that the
socket is expanding / contracting in such a way that it is applying torque
to the glue holding the bulb in the base....

I have seen intermittent lamps resulting from cheaply made sockets where
there was an unused switch leaf. I guess it was easier to disable the
switch leaf than to manufacture without it....Every time the socket warmed
up, the leaf bent because there was no knob to hold it in place...

My guess  is that if the sockets were all installed at the same time, they
are the same make. probably same production lot. Probably made in some
totally unknown factory in a remote location.  The rest of the lot are
probably scattered throughout the known world...

Just some thoughts, probably erroneous, but maybe worth a try.


Best of luck,

Martin

At 03:30 PM 7/16/01 -0400, you wrote:
{Quote hidden}

>{Original Message removed}

2001\07\16@155450 by Robert E. Griffith

flavicon
face
Thanks, I will try replacing the socket when I get some time.  To support
your idea that the socket is the culprit to the separating bulbs problem,
all the separated bulbs came from the same socket.

--BobG

{Original Message removed}

2001\07\16@155656 by t F. Touchton

flavicon
face
part 1 6995 bytes content-type:text/plain; charset=us-ascii
I have had this exact same problem with an outside fixture, and turned out
to be thermal in nature.  I improved the ventilation of the fixture, and
bent the bulb mount away from the thermal barrier and the problem went away
for good.  (For some reason the bulb was hovering about a 1/4" from the
insulator.  I increased this to about an inch.)

Scott



                   Martin Baker
                   <mbaker@OPTIME        To:     EraseMEPICLISTspamspamspamBeGoneMITVMA.MIT.EDU
                   INC.COM>              cc:
                   Sent by: pic          Subject:     Re: [EE]: Bulb Life -- Burned out bulb resurected
                   microcontrolle
                   r discussion
                   list
                   <PICLIST@MITVM
                   A.MIT.EDU>


                   07/16/01 03:46
                   PM
                   Please respond
                   to pic
                   microcontrolle
                   r discussion
                   list






I may not have a clue, but my guess would be that the problem is
mechanical. I would suggest swapping one of the sockets with a standard
replacement from a hardware store..

There are several possible issues, the most likely of which is that the
socket is expanding / contracting in such a way that it is applying torque
to the glue holding the bulb in the base....

I have seen intermittent lamps resulting from cheaply made sockets where
there was an unused switch leaf. I guess it was easier to disable the
switch leaf than to manufacture without it....Every time the socket warmed
up, the leaf bent because there was no knob to hold it in place...

My guess  is that if the sockets were all installed at the same time, they
are the same make. probably same production lot. Probably made in some
totally unknown factory in a remote location.  The rest of the lot are
probably scattered throughout the known world...

Just some thoughts, probably erroneous, but maybe worth a try.


Best of luck,

Martin

At 03:30 PM 7/16/01 -0400, you wrote:
{Quote hidden}

in
>its socket while it was not working.
>
>--BobG
>
>{Original Message removed}
part 2 8188 bytes content-type:application/octet-stream; (decode)

part 3 154 bytes
--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@161440 by Spehro Pefhany

picon face
At 03:05 PM 7/16/01 -0400, you wrote:
>I am embarrassed to say that I do not get it.  What's the 500w load in your
>diagram? In your scenario, is the faulty neutral at the breaker box or at
>the lamp?

Where I drew the // lines in it (below). The 500W load might be other lights,
whatever. The important thing is that it is higher current draw (lower
impedance) than the lamp.

If the neutral is broken entirely, then the voltage will divide across
the two loads. Assuming (for simplicity) the two loads are resistive, and
that the 100W lamp is R = 144 ohms, the 500W load is 28.8 ohms (fixed
for simplicity), then the 100W bulb would see 240 * (144/(144+28.8) = 200V.
Obviously it won't last very long at all!

If the loads on either side of the neutral are exactly balanced, then there
will be no obvious ill effects from breaking the neutral.

>Every outlet/lamp fixture in my house has 3 wires - what I typically think
>of as 'line', 'ground', and 'neutral'.  Ground and neutral are at the same
>potential and 'line' is +-120vac.  I think of ground as an alternate return
>path to ground in case the line is accidentally exposed. I have never quite
>understood why ground and neutral should be electrically isolated.

It's a safety issue. The safety ground is not supposed to carry current
except under fault conditions. Typically something like the housing of a
clothes washer is connected to ground. Imagine if it was connected to
neutral and the neutral went open (you don't have to think about the other
line to see this..) all of a sudden the metal housing is at 120VAC (in series
with the internal motor or whatever), which will happily fry you without
getting much voltage across it.

>So you are saying that with a faulty neutral, a 120vac appliance with see
>240vac?

It can see anything between close to zero to close to 240, depending on
how imbalanced the loads are. But a flickering (to dim) could just be a
bad connection in series with the load. Flickering (to more brightly)
pretty much nails it down to being a bad neutral.

Best regards,

{Quote hidden}

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
RemoveMEspeffKILLspamspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@163343 by Robert E. Griffith

flavicon
face
Thanks for the detailed explanation. That clears it up for me.

--BobG

-----Original Message-----
From: pic microcontroller discussion list [PICLISTSTOPspamspamspam_OUTMITVMA.MIT.EDU]On
Behalf Of Spehro Pefhany
Sent: Monday, July 16, 2001 4:17 PM
To: spamBeGonePICLISTSTOPspamspamEraseMEMITVMA.MIT.EDU
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected

At 03:05 PM 7/16/01 -0400, you wrote:
>I am embarrassed to say that I do not get it.  What's the 500w load in your
>diagram? In your scenario, is the faulty neutral at the breaker box or at
>the lamp?

Where I drew the // lines in it (below). The 500W load might be other
lights,
whatever. The important thing is that it is higher current draw (lower
impedance) than the lamp.

If the neutral is broken entirely, then the voltage will divide across
the two loads. Assuming (for simplicity) the two loads are resistive, and
that the 100W lamp is R = 144 ohms, the 500W load is 28.8 ohms (fixed
for simplicity), then the 100W bulb would see 240 * (144/(144+28.8) = 200V.
Obviously it won't last very long at all!

If the loads on either side of the neutral are exactly balanced, then there
will be no obvious ill effects from breaking the neutral.

>Every outlet/lamp fixture in my house has 3 wires - what I typically think
>of as 'line', 'ground', and 'neutral'.  Ground and neutral are at the same
>potential and 'line' is +-120vac.  I think of ground as an alternate return
>path to ground in case the line is accidentally exposed. I have never quite
>understood why ground and neutral should be electrically isolated.

It's a safety issue. The safety ground is not supposed to carry current
except under fault conditions. Typically something like the housing of a
clothes washer is connected to ground. Imagine if it was connected to
neutral and the neutral went open (you don't have to think about the other
line to see this..) all of a sudden the metal housing is at 120VAC (in
series
with the internal motor or whatever), which will happily fry you without
getting much voltage across it.

>So you are saying that with a faulty neutral, a 120vac appliance with see
>240vac?

It can see anything between close to zero to close to 240, depending on
how imbalanced the loads are. But a flickering (to dim) could just be a
bad connection in series with the load. Flickering (to more brightly)
pretty much nails it down to being a bad neutral.

Best regards,

{Quote hidden}

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=
Spehro Pefhany --"it's the network..."            "The Journey is the
reward"
KILLspamspeffspamBeGonespaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@164810 by Raymond Choat

flavicon
face
Yes they like the dark...ha

----- Original Message -----
From: "Robert E. Griffith" <EraseMEbobspamEraseMEJUNGA.COM>
To: <@spam@PICLIST@spam@spamspam_OUTMITVMA.MIT.EDU>
Sent: Monday, July 16, 2001 8:14 AM
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected


> I have been having a problem with the light fixture in my kitchen going
> through bulbs fast (bulbs lasting about a month). This fixture uses the
more
> expensive, large diameter bulbs.  When the last one went out, I did not
> replace it right away.  Several days later, it came back to life!
>
> Since then, it has gone out several times (for 2-7 days) but has, so far,
> always come back to life.
>
> I have measured the voltage in the socket during one of the bulb's dead
> periods and verified that there is power in the socket (117v).
>
> I imagine that somewhere in the bulb is an intermittent short.  The room
is
> air conditioned so temp does not vary that much (except when the bulb is
> on:)
>
> Another strange thing:  Three times now, when other bulbs have gone out in
> this fixture, the glass bulb separates from the metal socket while the
light
> is on and drops to the table below!
>
> So I guess my question is "Should I be concerned that this fixture is
> haunted?".  Should I call Bill? (Maurry - not Gates)
>
> --BobG
>
> {Original Message removed}

2001\07\16@172500 by Paul Hutchinson

flavicon
face
IIRC, The National Electric Code specifically prohibits using a common
neutral between the two phases.

With the neutral's only tied together at the service panel you avoid a very
dangerous situation when a neutral goes open outside the service panel.

___   120VAC
|   |-----------x    <----------x
| S |           |               |
| V |      [100W bulb]          |
| C |   N       |               |
| E |-----------x              240VAC
|   |                           |
| P |-----------x               |
| A |   N       |               |
| N |       [500W load]         |
| E |           |               |
| L |-----------x    <----------x
--- 120VAC


Paul

=========================================
Paul Hutchinson
Chief Engineer
Maximum Inc., 30 Samuel Barnet Blvd.
New Bedford, MA 02745
spamBeGonephutchinsonspamKILLspamimtra.com
http://www.maximum-inc.com
=========================================

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@174549 by Bob Ammerman

picon face
> IIRC, The National Electric Code specifically prohibits using a common
> neutral between the two phases.

I don't believe this is true.

When I wired my woodworking shop I installed several 12/3 w/gnd lines from
the service panel to outlet boxes containing  2 GFI's each.

I used separate (not ganged) 20A breakers to drive each phase (one on red
wire, one on black).

In the outlet box the neutral (white) was shared by both GFI's and the RED
and BLACK conductors each drove one GFI.

The electrical inspector specifically said this was a fine way to do it.

Also, the copy of the NEC that I have also contained no prohibition that I
could find against this.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)


> With the neutral's only tied together at the service panel you avoid a
very
{Quote hidden}

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@185401 by Jim

flavicon
face
> > IIRC, The National Electric Code specifically prohibits using a common
> > neutral between the two phases.
>
> I don't believe this is true.
>
> When I wired my woodworking shop I installed several 12/3 w/gnd lines from
> the service panel to outlet boxes containing  2 GFI's each.


The neutral is rated at one size smaller than the power carrying conductor.
So, if the two 110 outlets are rated to carry power equal to what the
neutral is rated than this configuration will work (30 amp neutral rating on
12/3 basically rating the outlets at 15 amps each). I am surprised that the
inspector allowed this on an industry outlet such as a woodshop that
normally requires a full 20 amps per outlet. I use this configuration all
the time when wiring houses. The bedroom circuits are under rated because
they may carry a clock, TV, or a lamp... normally all low power items.
Pulling a three wire saves money because the bedrooms are normally the
furthest from the panel.

Jim

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@185811 by Jim

flavicon
face
Although, I always make sure the power carrying conductors were on the same
phase so no 110 outlet box has 220 in the box. Big safety feature.. For they
serviceman down the road

Jim

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@192011 by Dwayne Reid

flavicon
face
At 05:23 PM 7/16/01 -0400, Paul Hutchinson wrote:
>IIRC, The National Electric Code specifically prohibits using a common
>neutral between the two phases.

Not correct!  Specifically, kitchen receptacles in homes are wired with 2
phases and a neutral: this allows 2 breakers (ganged) to feed a single
duplex receptacle so that plugging a toaster and an electric frying pan
into the top and bottom of a single receptacle does not trip a
breaker.  The local inspectors test for this by measuring the voltage
between the 2 hot terminals on each kitchen receptacle: if they do NOT
measure 230Vac, it fails the test.

Industrial wiring shares the neutral between the 3 phases for most 120V
outlets and for area lighting.  You tend to find dedicated neutrals only on
special outlets such as those dedicated for computers and such.

dwayne



Dwayne Reid   <TakeThisOuTdwayner.....spamTakeThisOuTplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax

Celebrating 17 years of Engineering Innovation (1984 - 2001)

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@214832 by Bob Ammerman

picon face
> > > IIRC, The National Electric Code specifically prohibits using a common
> > > neutral between the two phases.
> >
> > I don't believe this is true.
> >
> > When I wired my woodworking shop I installed several 12/3 w/gnd lines
from
> > the service panel to outlet boxes containing  2 GFI's each.
>
>
> The neutral is rated at one size smaller than the power carrying
conductor.
> So, if the two 110 outlets are rated to carry power equal to what the
> neutral is rated than this configuration will work (30 amp neutral rating
on
> 12/3 basically rating the outlets at 15 amps each). I am surprised that
the
> inspector allowed this on an industry outlet such as a woodshop that
> normally requires a full 20 amps per outlet. I use this configuration all
> the time when wiring houses. The bedroom circuits are under rated because
> they may carry a clock, TV, or a lamp... normally all low power items.
> Pulling a three wire saves money because the bedrooms are normally the
> furthest from the panel.
>
> Jim

12/3 neutral is 12 gauge (the one-size-smaller rule doesn't kick in until
you get to higher sizes, typical AL 4 (maybe AL 6) or bigger) and thus is
rated for 20A.

Also, neutral current worst case is when you have an unbalanced load: ie:
drawing 20A on one leg and nothing on the other.

I guess the thinking is that the probability of a badly unbalanced load goes
down when the guage goes up. This makes sense as long as the load is the sum
of a relatively large number of small loads. The idea breaks down if you
have just a few high power single phase loads. A (partially) contrived
example (something similar to this actually happened to me!):

A showerhouse at a summer camp.

5 20A outlets in the boys half on one leg

5 20A outlets in the girls half on the other leg

All the girls turn on their 2000W hair dryers at the same time, while the
guys are shaving with their 5W shavers....

Now you got quite a big neutral current!

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@215036 by Bob Ammerman

picon face
> Although, I always make sure the power carrying conductors were on the
same
> phase so no 110 outlet box has 220 in the box. Big safety feature.. For
they
> serviceman down the road
>
> Jim

This is, I believe, a violation of the code because you can end up with
double current on the neutral which exceeds its rating (and it isn't fused
to protect itself, either).

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@225323 by Robert E. Griffith

flavicon
face
Why couldn't you have the two circuits in the kitchen on the same phase as
long as they each have a 15-amp breaker back at the box?  Surely the single
phase could handle the combined 30-amp load, so what's the advantage of
having them on different phases?  I would think that any 240v appliance in
the kitchen would need it's own circuit, so its not for the combined 240v.

The book I used when wiring my kitchen showed alternating the circuits of
the 3 wire BX so that each box had only one circuit.

Wait a minute; maybe I just figured it out.  When there is load on both
circuits, if the circuits are 180 degrees out of phase then the current on
the common neutral would tend to cancel - creating a smaller current load on
the neutral wire.  If they were in phase, the current on the neutral would
be the sum of the two circuits so it would have to be rated for the sum of
the two circuits (30-amps).  Is that it?

Here's a somewhat related question.  In my basement, I have a chop saw on a
15-amp circuit that blows occasionally when the saw starts.  If the wire on
this circuit is thick enough, can I replace the 15-amp breaker with a 20-amp
breaker?  What gauge is rated for 20-amp?  It is a short run to the box and
it runs through conduit - not bx, so maybe I could just pull the heavier
wire if I need to.

There was originally a 240v circuit in this conduit.  Along the conduit are
120v receptacles and a single 240v receptacle.  I do not know whether they
shared any wires.  Could they - legally? Can you put 120v receptacles on a
circuit that is also used as half of a 240v circuit? In the box, a 240v
breaker is just two 120v breakers with a bar connecting them so that if one
trips, they both trip.

--BobG
{Original Message removed}

2001\07\16@233655 by Dwayne Reid

flavicon
face
At 10:51 PM 7/16/01 -0400, Robert E. Griffith wrote:

>Wait a minute; maybe I just figured it out.  When there is load on both
>circuits, if the circuits are 180 degrees out of phase then the current on
>the common neutral would tend to cancel - creating a smaller current load on
>the neutral wire.  If they were in phase, the current on the neutral would
>be the sum of the two circuits so it would have to be rated for the sum of
>the two circuits (30-amps).  Is that it?

Got it exactly!

>Here's a somewhat related question.  In my basement, I have a chop saw on a
>15-amp circuit that blows occasionally when the saw starts.  If the wire on
>this circuit is thick enough, can I replace the 15-amp breaker with a 20-amp
>breaker?  What gauge is rated for 20-amp?

My first attempt at fixing this would be to pull heavier wire to the saw
but staying with the 15A breaker.  Here is why:  if the wire is too small,
the voltage at the saw is too low and the saw takes too long to come up to
speed.  The breaker will handle surge currents only for a limited amount of
time.  Because the saw is still drawing too much current when that time
limit is up, the breaker trips.

12 AWG is the standard wire size for 20 Amps.  But in your case, I'd try
pulling 10AWG wire in.  If the 15A breaker still trips, then go for the 20A
breaker.  But the heavier wire may just fix the problem.

dwayne




Dwayne Reid   <TakeThisOuTdwaynerKILLspamspamspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax

Celebrating 17 years of Engineering Innovation (1984 - 2001)

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@234744 by Jim

flavicon
face
>What gauge is rated for 20-amp?
12 ga

>120v receptacles and a single 240v receptacle
120 (SP) and 240 (DP) ccts should not share wires

Jim

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\07\16@235604 by Robert E. Griffith

flavicon
face
>> if the wire is too small, the voltage at the saw is too low
>> and the saw takes too long to come up to speed

Cool, that is a totally new idea to me. I imagine it would also be better
for the saw if it had full voltage while starting up.

--BobG

{Original Message removed}

2001\07\17@031019 by Lee Jones

flavicon
face
> [broken neutral] Where I drew the // lines in it (below). The
> 500W load might be other lights, whatever.

>>> 120VAC
>>> o-------x    <----------x
>>>         |               |
>>>    [100W bulb]          |
>>> N       |               |
>>> o--//---x              240VAC
>>>         |               |
>>>     [500W load]         |
>>>         |               |
>>> o-------x    <----------x
>>> 120VAC

I've seen this up close.  Thought the story might amuse you.

I live in southern California.  Four years ago, a storm blew
through with _major_ wind storm damage.  Electric utility people
were totally overwhelmed.

Our neighbor asked me if I knew what might be wrong with their
power.  Certain appliances would only work if they had "enough"
light fixtures turned on, etc.  Weird behavior through-out the
house.  I knew that residential wiring frequently puts one phase
on the light fixtures and the other phase on the wall outlets.
So I suspected the neutral right away.

Breaker panel seemed OK.  Then I looked up.

Electric feed is overhead with steel messenger cable twisted
with two insulated wires.  Each insulated wire is one phase
from the pole mounted transformer.  Steel messenger cable is
used to carry cable tension and for the neutral return.
(Roughly balanced phases, so neutral carries lower current,
so steel is "OK", and they save money on wire.)

Wind had broken the steel messenger cable; insulated phase
cables were still intact.  But things would work if loads
were reasonably well matched on both power phases.  Mismatch
loads on the two phases and things behaved erratically.

I did a temporary repair.  I used rope around the feed cable
bundle tied to the entrance pipe to take up the physical
strain on the cable.  Then I used a car jumper cable to
reconnect the ends of the broken steel messenger wire.
Problem solved.

It was that way for 3 days until the local electrical
utility repair crew could get to it.  Repair guy fixing
it appreciated the kludge.  And I did get my jumper
cable back.

                                               Lee Jones

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@054449 by Roman Black

flavicon
face
Hi Bob, many of those 3-light fittings are NOT suitable
for larger bulbs. The socket itself might be ok but
the fitting won't take the total watts heat.

My 3-light kitchen fitting gets over 85 degrees C (yes
I have a infrared thermometer) with 60w bulbs in it.

When your bulb goes on/off intermittantly the filament
has failed. Broken filament. You're relying on luck
to make it connect. :o) Also, the symptom of the bulb
separating glass from the metal cap is a sure symptom
of excessive heat, fatiguing the solder that holds them
together. I guess your kitchen lights are on a lot,
and it gets hotter in there than other rooms, and you
have 3 larger bulbs as kitchens need a lot of light.

Try 2 compact fluoros in there, will reduce the heat
to almost nothing, and give good light. My kitchen
now has them. :o)

I also suggest checking the temperature of your home
light fittings, you might be surprised how dangerous
they are, most wiring cables are rated at 85'C and
my lights were at that temperature or higher...
-Roman


Robert E. Griffith wrote:
{Quote hidden}

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@065146 by Alan B. Pearce

face picon face
> I have been having a problem with the light fixture in my
> kitchen going
> through bulbs fast (bulbs lasting about a month). This
> fixture uses the more
> expensive, large diameter bulbs.  When the last one went out,
> I did not
> replace it right away.  Several days later, it came back to life!
>
> Since then, it has gone out several times (for 2-7 days) but
> has, so far,
> always come back to life.
>
> I have measured the voltage in the socket during one of the
> bulb's dead
> periods and verified that there is power in the socket (117v).

You do not say what sort of socket it is, but if it is a bayonet one I would
suspect the spring in one of the contacts is broken or lost tension due to
heat (possibly from using too high wattage bulb for the fitting? :)) Even if
it is a screw fitting the contact spring may have similar problems.

The other possibility is the wire in the back of the socket is only just
touching the pin, and replacing the bulb disturbs the socket enough to make
good enough contact for it to work until the heat corrodes the wire at the
point of contact again.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@073520 by Bob Ammerman

picon face
----- Original Message -----
From: "Robert E. Griffith" <.....bobspamRemoveMEJUNGA.COM>
To: <RemoveMEPICLISTspamspamBeGoneMITVMA.MIT.EDU>
Sent: Monday, July 16, 2001 10:51 PM
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected


> Why couldn't you have the two circuits in the kitchen on the same phase as
> long as they each have a 15-amp breaker back at the box?  Surely the
single
> phase could handle the combined 30-amp load, so what's the advantage of
> having them on different phases?  I would think that any 240v appliance in
> the kitchen would need it's own circuit, so its not for the combined 240v.
>
> The book I used when wiring my kitchen showed alternating the circuits of
> the 3 wire BX so that each box had only one circuit.
>
> Wait a minute; maybe I just figured it out.  When there is load on both
> circuits, if the circuits are 180 degrees out of phase then the current on
> the common neutral would tend to cancel - creating a smaller current load
on
> the neutral wire.  If they were in phase, the current on the neutral would
> be the sum of the two circuits so it would have to be rated for the sum of
> the two circuits (30-amps).  Is that it?

Yep, that's it.

> Here's a somewhat related question.  In my basement, I have a chop saw on
a
> 15-amp circuit that blows occasionally when the saw starts.  If the wire
on
> this circuit is thick enough, can I replace the 15-amp breaker with a
20-amp
> breaker?  What gauge is rated for 20-amp?  It is a short run to the box
and
> it runs through conduit - not bx, so maybe I could just pull the heavier
> wire if I need to.

14 guage wire --> 15 AMPS
12 guage wire --> 20 AMPS
10 guage wire --> 30 AMPS

> There was originally a 240v circuit in this conduit.  Along the conduit
are
> 120v receptacles and a single 240v receptacle.  I do not know whether they
> shared any wires.  Could they - legally? Can you put 120v receptacles on a
> circuit that is also used as half of a 240v circuit? In the box, a 240v
> breaker is just two 120v breakers with a bar connecting them so that if
one
> trips, they both trip.

I believe that this is legal. However, if you have any 240V loads, then you
MUST have a ganged breaker.

Actually, interally most 240V breakers are not just two 120V's with a bar
between them. In the olden days this was more likely true. Now the bar is
generally just cosmetic.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@073932 by Bob Ammerman

picon face
You may also have a faulty breaker, or the wrong one. Breakers are designed
to handle surges well above nameplate rating without opening just to get
motors started.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2001\07\17@075243 by Robert E. Griffith

flavicon
face
Thanks Roman, I will check into the compact fluoros, but the large diameter
bulbs is exposed and is an aesthetic design feature of the lamp, so I would
have to find nice looking ones.

The lamp is rated for 100W bulbs, and is designed specifically for the large
diameter bulbs.  But then, I guess not all of my designs work as well as I
would have liked either :)  The three bulbs are far apart and very exposed
to the air.  The ones that separated were all 60w in a 100w rated fixture!

In terms of heat, is it better to run 60w bulbs at full power or 100w bulbs
at less than full power with an X-10 dimmer?

--BobG

{Original Message removed}

2001\07\17@082553 by Bob Ammerman

picon face
----- Original Message -----
From: "Roman Black" <spamBeGonefastvid@spam@spamspam_OUTEZY.NET.AU>
To: <TakeThisOuTPICLISTspamspamMITVMA.MIT.EDU>
Sent: Tuesday, July 17, 2001 5:43 AM
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected


{Quote hidden}

So, if the bulbs can't stand the heat they should stay out of the kitchen?

{Quote hidden}

light
> > even when fixture has not been used for hours and I measured the voltage
in
> > its socket while it was not working.
>
> --
> http://www.piclist.com hint: The list server can filter out subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics
>
>

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@092252 by Olin Lathrop

face picon face
> In terms of heat, is it better to run 60w bulbs at full power or 100w
bulbs
> at less than full power with an X-10 dimmer?

Efficiency of incandescent bulbs drops dramatically as the power is reduced.
Therefore a 60W bulb will be cooler than a dimmed 100W bulb at the same
apparent light output (and less orange too).


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olinEraseMEspamembedinc.com, http://www.embedinc.com

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@094945 by Roman Black

flavicon
face
Bob Ammerman wrote:

> > When your bulb goes on/off intermittantly the filament
> > has failed. Broken filament. You're relying on luck
> > to make it connect. :o) Also, the symptom of the bulb
> > separating glass from the metal cap is a sure symptom
> > of excessive heat, fatiguing the solder that holds them
> > together. I guess your kitchen lights are on a lot,
> > and it gets hotter in there than other rooms, and you
> > have 3 larger bulbs as kitchens need a lot of light.
>
> So, if the bulbs can't stand the heat they should stay out of the kitchen?

Ha ha ha! Or... "Why do women have smaller feet than men?"
All in fun, ;o)
-Roman

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@101253 by Roman Black

flavicon
face
Robert E. Griffith wrote:
>
> Thanks Roman, I will check into the compact fluoros, but the large diameter
> bulbs is exposed and is an aesthetic design feature of the lamp, so I would
> have to find nice looking ones.


Hi Robert, the symptoms you mentioned seemed related
to excess heat. Probably the next step would be to get
a thermometer and do some simple tests. I know PICs
have a maximum heat rating, i'm sure light bulbs do
too. I bet your "nice looking" light fittings are
out of spec. :o)
-Roman

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@101622 by Douglas Butler

flavicon
face
> In terms of heat, is it better to run 60w bulbs at full power
> or 100w bulbs
> at less than full power with an X-10 dimmer?
>
> --BobG

In terms of Visable light/heat you are much better off running 60W bulbs
full out than 100W bulbs dimmed.  Also the color will be better.  It is
a blackbody curve thing.

Sherpa Doug

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\17@111428 by Jim

flavicon
face
>
> > Why couldn't you have the two circuits in the kitchen on the same phase
as
> > long as they each have a 15-amp breaker back at the box?

In the kitchen is not a problem. A phase to phase short is very exciting and
can be more potentially fatal. An electrican that expects 120 in a kitchen
box could get into something he would rather not have. Keeping a 120 v box
single phase is not a hard thing to do. Its basically electrical edicate.

> between them. In the olden days this was more likely true. Now the bar is
> generally just cosmetic.
>

The bar makes sure that one leg of a 240 v cct. does not remain hot when the
other side shorts out. True, taking the bar off makes two single 110
breakers, but never supply 240 with two SP not tied together

Jim

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2001\07\18@035720 by Bob Ammerman

picon face
> > between them. In the olden days this was more likely true. Now the bar
is
> > generally just cosmetic.
> >
>
> The bar makes sure that one leg of a 240 v cct. does not remain hot when
the
> other side shorts out. True, taking the bar off makes two single 110
> breakers, but never supply 240 with two SP not tied together

Right, _never_ supply 240 without both legs simultaneously broken.

When I said the 'bar was cosmetic', I was implying that in most modern
breakers, the actual tying mechanism is inside the breaker, and the bar has
no function other than to indicate to the user that the handles are tied.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2001\07\18@175745 by Jim

flavicon
face
> When I said the 'bar was cosmetic', I was implying that in most modern
> breakers, the actual tying mechanism is inside the breaker, and the bar
has
> no function other than to indicate to the user that the handles are tied.
>
So if you take a bar off of a DP breaker, both sides will still trip?

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2001\07\19@005424 by Bob Ammerman

picon face
----- Original Message -----
From: "Jim" <RemoveMEjimEraseMEspamspam_OUTCPCEMA.COM>
To: <@spam@PICLISTRemoveMEspamEraseMEMITVMA.MIT.EDU>
Sent: Wednesday, July 18, 2001 3:54 PM
Subject: Re: [EE]: Bulb Life -- Burned out bulb resurected


> > When I said the 'bar was cosmetic', I was implying that in most modern
> > breakers, the actual tying mechanism is inside the breaker, and the bar
> has
> > no function other than to indicate to the user that the handles are
tied.
> >
> So if you take a bar off of a DP breaker, both sides will still trip?

I believe so, with most modern breakers.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body


More... (looser matching)
- Last day of these posts
- In 2001 , 2002 only
- Today
- New search...