Customer has a 3Phase 100A subpanel protected by a 3 Phase breaker in the main distribution panel. Voltage is 120/240. Panel is wired with #6 from main breaker abour 20" to the subpanel. Load on each phase is about 28A, all 3 phases are within 28-30A. All loads are florscent lights w/ magnetic ballasts max on each circuit is 6A. So it seems balanced. Problem is that the panel and breakers are overheating. You can feel the excessive heat by touching the panel cover. No breakers are overloaded. Customer wants the panel changed out, before we do, any ideas on what may be causing the problem.
Overheating Panel
- Thread starter laudan
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jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Overheating Panel
Can we assume you have tightened all lugs ?
Can we assume you have tightened all lugs ?
Re: Overheating Panel
Overheated? What is the temperature? Breakers are allowed to get warm.
The general myth is that when we expect something to be cool to the touch but it feels warm it is quite often referred to as being hot. Breakers are allowed to get warm however and often do when they are loaded.
Because of their close proximity to the thermal overload element within the breaker frame loose load side cable terminations often cause heating but the breaker derates because of that heating and causes the breaker to trip thermally.
Line side connection may not cause the breaker to derate because the heat has to be transmitted either through the breaker frame and /or through the moving and stationary contacts before the heat can affect the thermal elements.
Overheated? What is the temperature? Breakers are allowed to get warm.
The general myth is that when we expect something to be cool to the touch but it feels warm it is quite often referred to as being hot. Breakers are allowed to get warm however and often do when they are loaded.
Because of their close proximity to the thermal overload element within the breaker frame loose load side cable terminations often cause heating but the breaker derates because of that heating and causes the breaker to trip thermally.
Line side connection may not cause the breaker to derate because the heat has to be transmitted either through the breaker frame and /or through the moving and stationary contacts before the heat can affect the thermal elements.
Re: Overheating Panel
Something to think about here is where you are getting heat rise at...
AFCI breakers can be warm/hot to the touch on the face driven by the electronics inside, although they will still be within the operating parameters of the breaker (U.L. 67 allows a 50 degree "C" temperature rise on load terminal with 80% load current)
A thermal scan would show warm spot at breaker face vs. at the terminals, which would be caused by loose connections.
Bottome line, you need to look at the actual temp rise and location of temp rise. AFCIs have electronics inside, so they will always run warner than a standard thermal magnetic breaker.
Something to think about here is where you are getting heat rise at...
AFCI breakers can be warm/hot to the touch on the face driven by the electronics inside, although they will still be within the operating parameters of the breaker (U.L. 67 allows a 50 degree "C" temperature rise on load terminal with 80% load current)
A thermal scan would show warm spot at breaker face vs. at the terminals, which would be caused by loose connections.
Bottome line, you need to look at the actual temp rise and location of temp rise. AFCIs have electronics inside, so they will always run warner than a standard thermal magnetic breaker.
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
Re: Overheating Panel
just wondering if anyone here's stuffed 30 or so AFCI's in a panel ??
just wondering if anyone here's stuffed 30 or so AFCI's in a panel ??
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Overheating Panel
I do think in the future i will try leave a space above and below an afci too allow heat to dissipate .Could the heat from an AFCI next to another breaker cause it to trip ?
[ February 05, 2004, 11:53 AM: Message edited by: jimwalker ]
I do think in the future i will try leave a space above and below an afci too allow heat to dissipate .Could the heat from an AFCI next to another breaker cause it to trip ?
[ February 05, 2004, 11:53 AM: Message edited by: jimwalker ]
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
Re: Overheating Panel
in my estimation, yes.
heat is heat to thermalmagnetics.
even the state inspectors here are tipping off EC's to space them out
of course Dini & Marchand re; NEC digest's 'Truth about AFCI's' (a two part article published after 210.12 was solid code in the 02' never alluded to this phenomenon..
quite telling, don't you think?
in my estimation, yes.
heat is heat to thermalmagnetics.
even the state inspectors here are tipping off EC's to space them out
of course Dini & Marchand re; NEC digest's 'Truth about AFCI's' (a two part article published after 210.12 was solid code in the 02' never alluded to this phenomenon..
quite telling, don't you think?
- Location
- Illinois
- Occupation
- retired electrician
Re: Overheating Panel
How hot do AFCI's run? Remember that standard breakers are designed to function correctly in a 105?F ambient.
Don
How hot do AFCI's run? Remember that standard breakers are designed to function correctly in a 105?F ambient.
Don
romex jockey
Senior Member
- Location
- Vermont
- Occupation
- electrician
Re: Overheating Panel
Don,
they run hot enough that they are , especially when stacked, hot to the touch.
that effect becomes even more notable multiplied x 30 afci's in a panel
this is even w/o a load, and i've many a customer complaint, and few answers from reps
Don,
they run hot enough that they are , especially when stacked, hot to the touch.
that effect becomes even more notable multiplied x 30 afci's in a panel
this is even w/o a load, and i've many a customer complaint, and few answers from reps
caosesvida
Senior Member
Re: Overheating Panel
close proximity of the breakers and no way for the heat to dissapate sounds reasonable. I agree with the temperature of breakers, are able to be hot without malfunction.
[ February 06, 2004, 01:03 PM: Message edited by: caosesvida ]
close proximity of the breakers and no way for the heat to dissapate sounds reasonable. I agree with the temperature of breakers, are able to be hot without malfunction.
[ February 06, 2004, 01:03 PM: Message edited by: caosesvida ]
tonyi
Senior Member
Re: Overheating Panel
I lied, I just counted 6 in a subpanel I put in my mom's place a few months ago - its a 12/24 QO and I installed the 60A main on top as a panel disconnect. The 6 AFCI's fill up one side and there's a 2-pole 25A on the other running the A/C compressor, and a couple of plain twins running other things, and a 2-pole plug on surge unit.
The stack of 6 AFCI's is somewhat warm, but I wouldn't say they're hot, maybe in the 90-100F range. The 2-pole 25A on the other side running the A/C is noticibly warmer than the stack of AFCI's when the compressor is running.
I lied, I just counted 6 in a subpanel I put in my mom's place a few months ago - its a 12/24 QO and I installed the 60A main on top as a panel disconnect. The 6 AFCI's fill up one side and there's a 2-pole 25A on the other running the A/C compressor, and a couple of plain twins running other things, and a 2-pole plug on surge unit.
The stack of 6 AFCI's is somewhat warm, but I wouldn't say they're hot, maybe in the 90-100F range. The 2-pole 25A on the other side running the A/C is noticibly warmer than the stack of AFCI's when the compressor is running.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: Overheating Panel
kschirra
GFCI's and AFCI's generate there own heat even without any load on them. This is because of the electronic circuits in them. so the main has nothing to do with these heating up.
kschirra
GFCI's and AFCI's generate there own heat even without any load on them. This is because of the electronic circuits in them. so the main has nothing to do with these heating up.
james wuebker
Senior Member
- Location
- Iowa
Re: Overheating Panel
I know that jimw asked if the lugs are all tight. Make sure you check the feeder lugs on the breaker that feed this sub panel & also all the neutrals. Feel the main wires that feed your sub panel and feed if they are hot. If they are something is loose with only a draw of 30 amp per phase. I'll check back later
Bye now,
Jim
I know that jimw asked if the lugs are all tight. Make sure you check the feeder lugs on the breaker that feed this sub panel & also all the neutrals. Feel the main wires that feed your sub panel and feed if they are hot. If they are something is loose with only a draw of 30 amp per phase. I'll check back later
Bye now,
Jim
Re: Overheating Panel
OKAY????? 120/240 3Phase would make it delta connected transformers, You stated 28-30 amps per phase, balanced lighting loads. Assuming that the Fixtures are 120v., Where's your 240v. load(s)? You can't balance 120/240 3Phase without 240v. loads, Unless Each Phase has 0 line amps. Am I Missing Something? A Corner Grounded Delta?
[ March 24, 2004, 01:42 PM: Message edited by: jgriffin ]
OKAY????? 120/240 3Phase would make it delta connected transformers, You stated 28-30 amps per phase, balanced lighting loads. Assuming that the Fixtures are 120v., Where's your 240v. load(s)? You can't balance 120/240 3Phase without 240v. loads, Unless Each Phase has 0 line amps. Am I Missing Something? A Corner Grounded Delta?
[ March 24, 2004, 01:42 PM: Message edited by: jgriffin ]
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