"Hot" Neutral - Electrician Talk - Professional Electrical Contractors Forum

Jupe Blue · 06-03-2009, 12:44 AM

Got a call from a good customer (residential) today. Says that he had a home inspector who wrote in his report that upon using a digital laser thermometer on the service panel, that the neutrals were "hot" (temp. wise, not electrically speaking). Wants to schedule me out to take a look and will show me the written report when I arrive. So, my questions:

What would be a "hot" temperature to read off a breaker, feeder or other conductor? Would the temp be relative to ambient temperature or relative to temps on components of the panel? At what temps. should I be concerned?

If you found a breaker or conductor that had a high temp, what would you do to troubleshoot the problem? I would look at all making sure all terminations at panel and devices are good and checking overall load on circuit. Anything else to be done without specialized equipment?

I welcome any thoughts on this before I go to this customer's house.

MDShunk · 06-03-2009, 12:49 AM

1) Most home inspectors are retards who washed out of real jobs.
2) How hot is hot? The conductor insulation rating is pretty darned high, so it can get hot and tolerate it.

Having said that, make sure that any MBWC's didn't get put on the same phase over the years and check to make sure everything is tight on the neutral bar (including service neutral).

480sparky · 06-03-2009, 12:53 AM

"Hot" is a relative thing.

I've had customers complain about dimmers being hot to the touch. I shoot them, and they're 110°F. They still worry it will start a fire. I reply, "If 110 degrees will start a fire, the entire state of Arizona will spontaneously combust every summer."

Personally, I'd be more worried about the 175° air in the ducts when the firnace is running.

ALL wiring and equipment under load will heat up. Heat is a by-product of current flow. Nothing more.

I'd ask for the HIs credentials.

MDShunk · 06-03-2009, 01:05 AM

If you find everything "normal" just tell them you tightened something. No sense getting in a pissing match with the homely spector.

TOOL_5150 · 06-03-2009, 03:12 AM

Quote:

Originally Posted by MDShunk

1) Most home inspectors are retards who washed out of real jobs.

Agreed

Worst $480 I EVER spent.

He found that my toilets wobbled but didnt bother to go in the attic to tell me mice/rats had devoured lots of romex sheath!

~Matt

John · 06-03-2009, 03:35 AM

Quote:

Originally Posted by MDShunk

If you find everything "normal" just tell them you tightened something. No sense getting in a pissing match with the homely spector.

And....
"Breakersize" the circuit breakers by turning them on and off a couple times. This gives the people watching the impression that you are doing something for the money that you are charging for the service call.

And as Marc said check to make sure everything is tight.

Carry On....that is all.

Toronto Sparky · 06-03-2009, 01:03 PM

Prob. overloading the neutral with all the new non-linear loads such as CFLs and such..
Sure no one thought about that.. Tunnel vision .. SAVE POWER. Just a thought.

480sparky · 06-03-2009, 01:08 PM

If the neutral is overloaded because of a MWBC installed on a tandem breaker, that is the problem.

Of course, we can't expect a HI to understand MWBCs on piggybacks.

Zog · 06-03-2009, 02:24 PM

Quote:

Originally Posted by Jupe Blue

Got a call from a good customer (residential) today. Says that he had a home inspector who wrote in his report that upon using a digital laser thermometer on the service panel, that the neutrals were "hot" (temp. wise, not electrically speaking). Wants to schedule me out to take a look and will show me the written report when I arrive. So, my questions:

What would be a "hot" temperature to read off a breaker, feeder or other conductor? Would the temp be relative to ambient temperature or relative to temps on components of the panel? At what temps. should I be concerned?

If you found a breaker or conductor that had a high temp, what would you do to troubleshoot the problem? I would look at all making sure all terminations at panel and devices are good and checking overall load on circuit. Anything else to be done without specialized equipment?

I welcome any thoughts on this before I go to this customer's house.

Well a laser thingy isnt worth the $20 he paid for it but here are the recommened actions from an IR survey

480sparky · 06-03-2009, 02:33 PM

Quote:

Originally Posted by Zog

Well a laser thingy isnt worth the $20 he paid for it but here are the recommened actions from an IR survey

Gee, did I get ripped off. I paid $875 for mine.

Zog · 06-03-2009, 06:12 PM

Quote:

Originally Posted by 480sparky

Gee, did I get ripped off. I paid $875 for mine.

Still worthless in this application. Only tells a small part of the story. Dont get me wrong, I have one too, but it is nothing like an IR camera in the hands of a certified thermographer.

Kevin J · 06-03-2009, 06:49 PM

Quote:

Originally Posted by Zog

Still worthless in this application. Only tells a small part of the story. Dont get me wrong, I have one too, but it is nothing like an IR camera in the hands of a certified thermographer.

Care to elaborate? I'm having trouble trying to figure out why a laser thermometer is worthless in this application. NASCAR mechanics use them all the time to temp various engine parts; they don't use IR cameras for this. Don't get me wrong, I think IR cameras are great, but sometimes its a little overkill.

MDShunk · 06-03-2009, 06:53 PM

Quote:

Originally Posted by Toronto Sparky

Prob. overloading the neutral with all the new non-linear loads such as CFLs and such..
Sure no one thought about that.. Tunnel vision .. SAVE POWER. Just a thought.

You'll never in your career see a neutral overloaded because of that.

480sparky · 06-03-2009, 06:59 PM

Quote:

Originally Posted by Zog

Still worthless in this application. Only tells a small part of the story. Dont get me wrong, I have one too, but it is nothing like an IR camera in the hands of a certified thermographer.

And there are apps that an IR camera is worthless, and an IR t'meter will rule.

Zog · 06-03-2009, 07:01 PM

Quote:

Originally Posted by Kevin J

Care to elaborate? I'm having trouble trying to figure out why a laser thermometer is worthless in this application.

Just tells you something is hot, you dont know what so comparing those values to ambeient or other equipment and using that ifo to make any recomendation is worhless. Reflection, radiation, etc can all effect those readings.

Quote:

Originally Posted by Patrik2075

NASCAR mechanics use them all the time to temp various engine parts; they don't use IR cameras for this.

What dies that have to do with the price of rice in China? Or electrical equipment evaluation for that matter?

480sparky · 06-03-2009, 07:12 PM

Quote:

Originally Posted by Zog

Just tells you something is hot, you dont know what so comparing those values to ambeient or other equipment and using that ifo to make any recomendation is worhless. Reflection, radiation, etc can all effect those readings.

What dies that have to do with the price of rice in China? Or electrical equipment evaluation for that matter?

So an IR camera tells me a lug is 238°F, and an IR thermometer tells me it is 238°F. What's the difference?

MDShunk · 06-03-2009, 07:19 PM

Quote:

Originally Posted by 480sparky

So an IR camera tells me a lug is 238°F, and an IR thermometer tells me it is 238°F. What's the difference?

Ambient compensation on the IR camera is pretty handy. They were demo-ing some IDEAL IR cameras at the supply house today. They looked like toys.

480sparky · 06-03-2009, 07:23 PM

Quote:

Originally Posted by MDShunk

Ambient compensation on the IR camera is pretty handy. They were demo-ing some IDEAL IR cameras at the supply house today. They looked like toys.

Is ambient compensation the same thing as emmisivity?

Jupe Blue · 06-03-2009, 07:56 PM

Quote:

Originally Posted by Toronto Sparky

Prob. overloading the neutral with all the new non-linear loads such as CFLs and such..
Sure no one thought about that.. Tunnel vision .. SAVE POWER. Just a thought.

The job that I did most recently for this customer was to install a high end lighting system (Control 5). Replaced 120 switches with very expensive ($100 each) that are computer controlled. It's the kind of system where you can turn your lights on from the office, set multiple lighting scenes, etc. Sold to the customer by a local high end AV company. I did the install of the switches only. The AV company did all the programming. Am being called back now (a year later) to replace 6-8 of them and also check out the "hot" neutral.

I'll let you know if the 'hot' neutral is associated with the lighting circuits.

steelersman · 06-03-2009, 08:01 PM

Quote:

Originally Posted by 480sparky

If the neutral is overloaded because of a MWBC installed on a tandem breaker, that is the problem.

Of course, we can't expect a HI to understand MWBCs on piggybacks.

Maybe I'm wrong but I don't think that an overloaded neutral on an improperly installed MWBC will cause the main neutral to overheat. They have nothing to do with each other in that regard.

After re-reading the OP I see that he isn't necessarily talking about the main neutral. Sorry. Thought he was.