I appreciate all the suggestions and information and will pass them along to my friend who is currently without internet access. The permit inspector came out for a field check and gave him several different options but would not say which is better, just what would be acceptable, so we're just doing some resarch. bigbird: Good tip on keeping the fridge etc. off of the GFCI. Nothing like waking up to melting ice cream and warm milk. billhart: interesting information. The AFCI breakers will only go on the bedroom circuits as per code requirement here. homeinspector: not sure if I'm understanding you correctly but this will be an interior application. Not sure if the GFCI breaker would still be more sensitive here and make a GFCI receptacle unnecessary. peter racer: sorry for not being clearer. The GFCIs and AFCIs are separate breakers, not the combos. This is an old house with Siemens breakers.

Thanks for the excellent responses. Currently I can answer these questions. 1) Initially the service entrance voltage was 140 - 141V. Way too high. A transformer supplying power to our unit was changed and readings are now correct. Oddly, at 141V the tripping was just as frequent. I would have thought higher voltage would have lowered the Amps drawn, and there would have been less frequent tripping. Can this high voltage (for a couple of months during construction) have caused the breakers to become prone to tripping? Voltage is now correct at both ends of the run. No run is longer than 75 feet or so from the main panel. 2) I kept the nature of the equipment back as it might cloud the issue a bit. Yes there is an inrush as this is studio flash equipment. That being said, there is no problem using this gear anywhere else in the city (I have been). Even the 15A on the stove is fine, but even a 30A SqD trips repeatedly. The units plug in with standard 16GA cords. I have changed the cords to 15' 14GA heavy-duty high-visibility (orange and black) cords mostly for visibility. The equipment repair technician says a transformer charges capacitors and only basic switches and so-on are between the line-in and the transformer. No capacitors directly connected to the line-in. There is a 'slow' setting (or gentle) on the unit for situations where the units must work on non-dedicated circuits that already have significant loads on them. This 'slow' setting trips as often as the normal setting. Again, they work everywhere else (on normal setting), even the stove outlet. 3) Counterfeit: I compared a breaker to the photos in the article. #C is not identical. Most of my tab is exposed, not 1/2 as pictured otherwise they match. 4) Multi-wire branch: I think so, 1 Neutral for 2 circuits. A single unit can trip a breaker or several units at the same time can trip 1 or more breakers in no particular pattern. My previous set-up was 12GA 3-wire BX cables with 2-20A sharing 1 neutral with no issues. 5) The breakers are QO type HACR 20A. 6) An ammeter was put on the units. There is a very brief peak over 20A. It measures between 28 to just over 30A. There was some talk about this brief peak measurement being unreliable for an exact figure. A cheaper meter read anywhere from 20A-38A. A better quality Fluke was typically under 25A. The 30A SqD trips with the same frequency as 20A so simply swapping to 30A (even in the short term) isn't an option. Thanks for your knowledgeable responses and effort to help with this. Tom

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"Only the breaker would, if enough total current was passing." Well, sort of. Just to dispel any possible confusion: A GFI breaker implements two functions. The first is overcurrent protection. The breaker trips if the total current drawn from the circuit exceeds the breaker's rating. For branch circuits this is normally 15 or 20 amps. The more it exceeds the breaker's rating, the faster the breaker trips. The second is ground fault protection. The breaker trips if it detects that the current is asymmetrical across the power line. The amount of asymmetrical (ground fault) current that trips the GFI part of the breaker is MUCH lower than the current that trips the overcurrent part . (Confused yet?) To explain this second function: it's not 100% accurate to describe it this way, but it's easier (I hope) to understand if you think of the electricity as going out the hot side of the receptacle and coming back in the neutral side. The GFI monitors both of these. If the amount of current coming back is less than the amount going out, some of it must be "leaking" to ground. That leakage might be going through a person or animal, risking shock or electrocution. So when the GFI sees that, it instantly opens, shutting off the power. With most GFIs, an imbalance (fault current) of 5 milliamps (0.005 amps) is enough to cause a trip.