400 Amp service?

[Mark P]

First let me say how much I appreciate and enjoy this site. Since I started inspecting last year I visit the site almost daily and have asked quite a number of questions and always get good/educational responses sometimes flavored with a bit of sarcasm for good measure. Well here is another area I need some education on and I thank you in advance.

There are two 200 amp panels side by side (200 amp breakers w/ copper 3/0 AWG), there are 2 meters outside. I believe the panel on the right is the main and the one of the left is a sub, but I’m really not sure. Do they jointly provide 400 amp service to the house?

Thanks again.

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[Erby]

It's fairly common around here to see one meter and two 200 amp panels fed from it. Both have a main breaker and neither is sub to the other.

Woudn't guess that your's is either. One meter feeds one panel. Other meter feeds second panel. I don't see anything in your photos that would lead me to believe one (main) panel is servicing the other (sub) panel.

[Richard Moore]

I agree with Erby. For one to be a "sub" of the other there would have to be a large 2-pole breaker on the bus bar with 3/0 feeders. Don't see that. Plus you have the two meters, which is unusual, but another indicator that both panels are service equipment. I'd say you have a 400-amp service.

[Mark P]

Thanks, for the advice.

[Jim Katen]

Yes, it's a 400-amp service. But I'm going to guess that one meter feeds both 200-amp panels and the second meter measures the use of whatever's controlled by the 2nd breaker down on the left side of the right panel.

Do you happen to know what that breaker is feeding?

- Jim Katen, Oregon

[Richard Moore]

Damn...I missed the donut! That doesn't happen as often as it should. [:-chef]

MIL?

[Mark P]

Jim, The 100 amp breaker is probably for the electric furnace. What is the donut for?

[Richard Moore]

Mark...Jim probably has a better explantion, but my crude one is...

The donut is a magnetic device, much like a clamp-on multi-meter, that senses the amperage flowing through the conductors and can be used to drive a remote or second meter. I've seen it a couple of times in homes that have been converted to "duplexes" or have mother-in-law apartments. In those cases it was the feeds to a sub-panel within the smaller unit that were being monitored. The extra meter was inside though in both cases...presumably the landlord (read homeowner) did the calculations on splitting the electric bill and charging the tenant. Did ths home have "separate" quarters?

[Jim Katen]

Originally posted by AHIS

Jim, The 100 amp breaker is probably for the electric furnace. What is the donut for?

Richard explained it. The donut senses current use and tells the meter.

I suspect that the meter was installed to monitor furnace use and determine how much of the home's power is used for space heating. Perhaps the home has some special energy-saving features and this is how they keep track of how well they work.

- Jim Katen, Oregon

[Mark P]

There are no other buildings. It had an electric furnace and a wood burning stove next to the furnace that used the same duct work as the a/c and furnace. Mike educated me on SIPS construction yesterday (and I did additional research http://www.sips.org/) and I beleive this is a SIPS house, (thanks HAUSADOK). The realtor claimed total heating cost is less than $100 per month during winter, so maybe the builder put the donut on to monitor heating cost.