mtwitty

The NEC states that the OCD is "not to exceed" 150% of the rated current. 422.11(E)(3) At 208 volts, that current would be 24.4 amps. The next standard size breaker is 25, which is the only one allowed in this scenario.

I don't like the double-tapped neutrals and the lack of handle ties on the MWBC's.

I think the primary function is binary. To gather all available pertinent information relating to the home. To accurately and clearly relay that information to the client.

Both 25 and 30 amp are compliant if the supply is 240 volts. If the supply is 208 volts, only a 25 amp breaker is allowed.

Cool micrometer. What brand is it?

Even if the mouse gets in, a trap is waiting for him.

#3 size are not allowed to be used in parallel. 1/0 AWG in the minimum size allowed for parallel feeds, per 310.10(H). For that reason alone, it's wrong.

The panel is a 200 amp, which in '92 allowed 40 breaker poles. The tandem is not allowed in that panel. The discoloration looks more like some type of chemical contamination than heat damage, but still may be a concern. There is some obvious paint overspray. I don't call out Challenger panels just because of their brand, particularly the newer ones like in your photo. There are many examples online of some failures of these panels. I have a pretty extensive photo library of failures on ITE, Siemens, Square D, Cutler Hammer, and others. The Square D breakers are not listed for use in that panel. AFCI breakers were not available in '92, so there really is no "listed" AFCI breaker for that panel that I know of......possibly Siemens, but doubtful. I think providing the AFCI protection is a positive safety upgrade that outweighs the non listed breaker issue.

KVA=apparent power=power before used. KW is power under load. (power consumed) So, to find actual KW usage, the power factor must be in the calculation. At least that is how I interpret it.

I defer to Marc. This falls in his wheelhouse and he is much more qualified to give you a quality answer.🙂

Hi Doug. to find the KW under the running load you would calculate: 208 x 600 x .8 x 1.732 =172,923/1000 =173 KW. if your generator is rated for 400 KW, you would be running at about 43% of full capacity. Is that what you are asking?

Hi Marc. It is under "Branch circuit, Multiwire" in article 100.

Hi Jim. Got to get picky here. Technically, any circuit that has two hots and share a neutral is a multi-wire circuit....even range and dryer circuits.....according to NEC definition. The main difference in requirement would be that if supplying a 240 volt appliance, a common trip would be required. That being said, I think what Johnny was asking was about multi-wire circuits that supply two 120 volt loads and how to identify. Your explanation totally covered his question. You know how nerdy I can get.

Tim, that circuit is most likely sharing a neutral with another circuit.....very common in older wiring installations. The imbalance of neutral current in the two circuits will cause the GFCI to trip, or as Marc said, there could actually be a ground fault on the circuit. If it is sharing a neutral with another circuit, your customer may just have to lose their affection for the old plates. Then you can use GFCI receptacles for the countertop receptacles, as long as you don't use the load terminals for other downstream outlets/receptacles.

It was a pleasure meeting you in NOLA, Marc.