Documented under sized

Here is how I document undersized breakers and or circuits. Top right breaker is a 60 amp double pole at the meter base feeding a sub-panel in a basement IR image was taken right before the breaker tripped under load test. The breaker was varying its amp load 56 to 62 amps when it tripped I terminated the test and begin writing. I luv it when the Realtor is sitting in the house and the lights go out

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What’s undersized?

The 60 amp breaker and more than likely the wire size feeding the sub-panel in the basement That had a 4 ton A/C unit electrical cook stove, dryer and all of the light circuits and some wall outlets all on one 60 amp breaker

What do you mean “more than likely” the wire size? Its pretty cut and dry as to what size wire can be used where.

Just a ply of words I don’t quote wire sizes I let the sparkys make that call. I like the words (appears to be):D:D

How did you load test this breaker?

Ahh, so you’re saying that based on the large load the 60 amp feeder is too small?

So how did you report this? Did you report that the wire was undersized? What was your evaluation as a Level III thermographer?

Yes sir that would be what I was implying being I had a 72 degrees above ambient on the wires, the amount of amp draw, the size of the breaker and the size of the wire. Call in the sparky and let them sort it out. BTW that 60 amp breaker was feeding the sub below

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I use all in house built in appliances all the light ceiling fans bathroom /kitchen exhausts and anything else available to create a load on the panels

Linas I had temps on both feeder conductors that was close to the same indicating no loose wires that the temp was created by excessive amp. I will just report What I observed and nothing more. I saw an excessive temp and I saw the breaker trip and that is what will be in the report let the sparky determine why.

That panel has some problems too, like the big green screw in the neutral bus. :wink:

That is why the sparky is coming I had the feeling that Harry did his own wiring


(1) Was the wire rated for 90C? That is 194F…so the wire may be 44*F below its maximum operational temp. Being electrical, there probably is a good saftey factor in that temp.

(2) In electrical as in HVAC, the concept of diversity is used in designing codes, loads and demands. Is there even a slight chance that all the appliances, AC, bath fans, all the lights, vacuum will be on at the same time? For example, in our codes with a house with individual baseboard heaters, a circuit fed with #12 AWG can have 4,800 watts of heaters potentially drawing 20 amps at odd times but… the code talks a lot about designing for 80% loading in many instances.

(3) In this case where you have no temperature difference on the 2 conductors probably indicating a balanced circuit/load distribution on both legs of the service, I may have done a demand/load calculation…it may have met code requirements for sizing.

It’s possible that Charley’s feeling about the feeder being too small are accurate but as Brain stated the only real way of knowing is to perform a load calculation.

I do find it surprising that in Canada you can run a 4800 watt heating load on a 20 amp, 240 volt circuit.

I agree that it looks like a lot of breakers/load for a 60A subpanel. Just be carefull how you report it. An electrical profession should do a feeder load calculation. Dont need a FLIR or “load tests” (careful there my friend) to tell me that (duck) … :stuck_out_tongue:

And neutrals/grounds on the same bar, etc …

I’ll do the smaller simpler ones like this seems to be. Saves calling in the electrician ( I hate to refer out to another pro unless really serious or totally outside my skills*) but in this case a sparky is needed anyways.

*3 weeks ago…Sometimes I wonder though!! I’m now questioning the “fix” recommended by a structural PE on a 12-13’ foot high bacony/deck supported only by diagonal braces back to the side of the house foundation. 1/2 the butt-nailed only joists (no hangers) had already pulled 1.5"-2.5" off of the ledger. I called for 3 properly done vertical 6"x6" posts + other code items or consult a PE on keeping the existing.

A PE was consulted…he called for 1 vertical post only at 1 corner…I won’t be going on the deck!!

I can do them too, but only if I’m being paid for that level of service (e.g. comprehensive commercial inspection) … :wink:

That can be a slippery slope also, since inspection/construction attorneys say to always keep a consistent level of detail in doing the inspection and then reporting the findings. If you do a calculation for the subpanel feeder do you also do calculations for service feeders, heating/cooling loads, roof/floor framing and beams, thermal envelope, gas piping sizes from equipment/appliance BTU ratings, etc … :shock:

Houses are quite simple entities. I don’t include the calcs in the report…do them just to satisfy myself that the service/subpanel is adequate for the space served.

It’s known as the 125% rule…CEC Section 62-114 (6), (7), (8 ) [125% of 80% = 100% of wire capacity in heating circuits only]

The previous Chief Electrical Inspector would not allow it to be applied (he’s working in Texas now); his recent successor does…figure that!!!

The old chief would only allow 3840 watts (16A x 240V) per #12 feeder (20A)/circuit, sticking right to the general 80% rules/guidelines (80% of 20A= 16A). In New Brunswick where I learned residential wiring (many years ago), the inspectors were not so strict to the letter of the codes and would allow 4000 watts per circuit.