System I inspected yesterday, Wow!!

This is the electrical service for a 4,000 sq. ft., 46 year old house that I inspected yesterday. Maybe I’m a virgin, but I’ve never seen anything quite like this in a residential setting. Besides these panels, there were also 3 large sub-panels in other parts of the house.

Did have one question, how do you folks feel about the tags in the panel in the last picture?








There was a spirited discussion on your question recently. Follow the link:

Damn. Maybe a prior owner worked for the poco…

thanks, Michael!

800 or 1200 amp service?

Mark, what kind of business were they operating there?

Would you believe that it was just 400 amp.

No business that I’m aware of, and not even a workshop or anything like that. Just a large, 1960 era contemporary private residence, with a lot of eccentric electrical stuff.

There’s a lot of lighting with multiple switches to turn every light on and off from various locations and all of the light switches are on relays. Just not your typical three way switches. A security system , of course. There’s some type of driveway heating system to melt the snow. Apparently they originally hung their clothes on a clothes line in the basement and there’s a large exhaust fan to pull the moisture out of the basement. Originally it was all Radiant ceiling heat before they installed some heat pumps and about four of the panels on the upper right contain relays for that. A swimming pool. Just a lot of stuff. The large commercial type main breakers just kinda surprised me.

No. That main disconnect looks like at least 800. If it is only a 400amp they spent alot of unnescearry monies.

How did you write this up? the pics are small but it would appear to be above my level of expertise.
Regards Kevin

I regularly see 400 amp service in this area. Large homes, larger service.

I have eve started to see 480 amp, commercial main disconnects in some large homes with 3 or 4 load side distribution boxes.

Better bone up on commercial electrical installations, that is where these guys are going.

What a time to be an inspector.

Even so, all of that is nowhere near needed for a simply 400amp install.

I have seen a 1200 amp service in a house. And I have installed more 1200 and 1800 amp installations than I care to remember. Not to mention some much larger than that. There is nothing like working on a motor in a factory that is 3600volts.

Was your clients last name “Frankenstein”?


Just make sure they are not sizing the SE conductors via 310.15(B)(6) in those 480A installations big guy…lol…:slight_smile:

Ensure they size according to 310.16 and understand even in residential…using commercial equipment…that being OVER 400A has some things they need to be aware of…:slight_smile:

No, I double checked. The main disconnect was clearly stamped 400 amp. I was surprised too. The type of breakers they had seemed like over kill, but maybe the builder got some sort of “deal” from some supplier that year. Who knows?

Well first, I stood back and took a deep breath :slight_smile: , and just soaked it all in. At first, I thought too, that this just might be over my head. (I don’t pretend to be an electrician). Fortunately, though, I was alone on this inspection (homeowner passed away and my clients are not in the area yet, business transfer) so I decided to just take my time, go for it and make it a learning experience.

Basically, I just treated it like any other inspection and focused on one component at a time. I actually did open up every panel. I don’t wear a watch when I’m on an inspection, but I think that I spent about 1 1/2 hours just looking at all of the electrical panels. Actually, the big ones, though they look intimidating, are just big metal boxes with 2 big fuses in each of them, with a throw switch (yea, i know, that’s simplistic). And the several panels of relays, basically made sure they worked, no scorching, no clattering, etc. I used to sell spas/hot tubs and worked on them some. The relays were pretty much the same as I would see in older spa packs. All the sub panels I just treated like any other sub.

I even opened up the main disconnect. As you commercial guys probably know, to open up a panel like that, you have to throw the switch off. I thought about that for a long time and considered what, if any consequences there might be to shut off all of the power to the house, but decided what the heck, in for a penny in for a pound ( or whatever the saying is). I put on my head lamp, turned on my second flashlight, and went for it.

And I lived to tell the tale :slight_smile: .

Yea Will, I see a lot of 400 amp services on newer, large homes, as well. It seems to be getting fairly prevalent. It was the nature of this equipment that I found unique and interesting. I hadn’t ever seen anything quite like it in a residential home before.