Multi family building electrics

Guy wants to know if there was any aluminum wiring, so I look. No aluminum, but I don’t understand how this can work. Obviously it does, because its a fully occupied 1962 three floor walk up with 6 apartments in not bad condition. Main panel has a 100 amp main breaker, it feeds 7 60 Amp circuits, one to each apartment and one for the building, each has its own meter. I did not go into any of the apartments, but I assume each apartment has a 40 Amp range circuit. So what happens on say, Thanksgiving day when every range has 4 burners glowing along with the oven roasting a turkey. Even if each apartment is only drawing 20 Amps the total is over 100? Electricity is mysterious stuff, what am I missing? This post request is for my education :slight_smile:

IS it possible that they have natural gas ranges?

Greetings Erik,

You are not missing anything actually. It is all about diversity and the fact that in your example “ranges” are not a continuous load. The range cycles, all of the ranges cycle (and gas ranges are possibly being used) and at the end of the day the current on the system will fluctuate. Ignoring any potential issued we are not able to convey via actual inspection, the fact that it is functioning and not causing an issued with the main OCPD tells me that it is diversified in it’s loads.

Now, will that always be the case we have no idea and can’t actually inspect for that based on your information and that non of the units have been investigated and clearly no load calculations have been done…but we do experience a fair amount of diversity in these applications.

Shorter answer is (based on your range question) the units cycle and their is enough diversity that combined it has not caused an issue on the main overcurrent protection.

Thanks Paul and Robert, based on what I usually see in this type of building there are no gas ranges, The gas line comes into the mechanical room for the boiler and water heater, and ends there, so no gas ranges. Typical for this type of building is a 60 Amp sub panel with a 40 Amp breaker for an electric range in each unit, and a 60 amp breaker in the main panel is what I see feeding each meter. Edmonton has a fairly vigilant group of code inspectors, especially electrical, and the electrical inspector will also be a journeyman electrician, so not likely the setup I saw is not code compliant or not inspected when installed.
Not sure what is meant by cycling, would that be the elements turning themselves off and on with a temperature control? I have not seen ordinary electric ranges with old school removable top elements do that, just the oven elements.
I know the question of how many amps for a 100 amp double pole breaker has been asked and answered in this forum, but if each leg can move 100 Amps, doesn’t that actually mean that a maximum of 200 Amps can be delivered by a 100 Amp service? If so it would explain a lot.

That has got to be the smallest service for a 6-unit building I have seen. 100A is minimum for a single family now.

Indeed but that 100A doesn’t apply to the individual dwelling units.

If 7 units are being fed through that 100 amp disconnect, why does it not apply?
Maybe some of those units experience high instance of OCPD activation.

An apartment building is not a single family dwelling . Therefore that requirement is not applicable .

I agree, the apartment is a Dwelling Unit as defined by Article 100 of the NEC but it not a Dwelling, One Family which would be in a building that consists solely of one dwelling unit.

A single family dwelling is just that,a dwelling for a single family.

I am curious as to whether or not this complex has gas appliances.