Will your home inspector tell you if your electrical service is too small?

30 amp service

While information technology goes beyond the scope of a home inspection to perform load calculations, occasionally I'll practise a crude calculation if I get concerned that an electric service is too minor for a house.  If the service size from my rough adding comes up likewise close to the actual service size, I'll recommend having an electrician perform an official load calculation... and I call back I've washed this twice.  Ever.

At almost every domicile inspection, I detect i of ii things:  either the electrical service is outdated and obviously too small, such as the 30 amp service pictured at right, or the service has been upgraded or over-sized and is plenty large enough for the habitation.  I don't find much in-betwixt those two.

I got to thinking about this while inspecting a iii,600 sf house in Plymouth for an old friend from high school.  This home had a 100 amp electric service, which seemed too small for that size of a house.  I considered recommending an electrician to do a load calculation on the house, but I first plugged in a few numbers at an online load calculator - http://www.electricalknowledge.com/SFDLoadCalc.asp .

I didn't have all of the verbal numbers that I needed, so I guessed on a bunch of them, such as the VA ratings on the garage door openers, garbage disposer, dishwasher, and microwave.  I put in 1800 VA for each 1 of these, which is certainly way likewise high, just it makes me feel improve almost guessing - at least I'm non guessing on the low side.

This home was heated with a gas furnace, had a gas clothes dryer, a gas water heater, and a gas oven.  The only major 240 volt appliance at this home was the air conditioner.  This is pretty mutual for a habitation in Minnesota.

Can you lot guess what the calculated service size was?68 Amps.

Granted, my calculation probably wasn't perfect, and I'm not certain that this online load calculator was completely accurate, but this was enough to make me not worry about the service size.  When I took an electric inspection form many years agone, nosotros had to perform a lot of load calculations for fictional houses, and I learned enough to know that if most of the major appliances are gas, a 100 amp service is probably enough enough.

I invite you to plug in the numbers from your own abode at the online load calculator that I linked to above - you lot might be surprised at how small of a service you could actually get away with.  For the record though, the smallest allowable service for a new dwelling house today is 100 amps.

Reuben Saltzman, Structure Tech Home Inspections - Email - Plymouth Home Inspector

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