Looking at new home power

Hey guys,

New home hunting here. I’ve got my eyes set on a new home and as part of inspection, I took a look at the breaker box. It’s got two 100 amp breakers (220v circuit), two 50 amp breakers and four 40 amp breakers… These seem like some high powered circuits. I’d have to run through the house again to see if there are sub-breaker boxes with smaller breakers; but I can’t recall seeing any.

Are the high amperage breakers normal?

I’m planning to get an electrician to run a pair of dedicated romex lines to the to-be-christened listening room from the breaker box. What amperage should those breakers be? Should I go for above-average gauge wiring (8 or 6awg)?


100A sounds about right.

Where do you reside? My residence is in the United States. My house was built with a 125 amp panel, and upgraded to 200 amps when I installed Solar PV.

I have a couple of 50 amp breakers, and the rest are 15-40 amps. I have a single dedicated 20 amp circuit for my entertainment center using 10 gauge Romex. How long is the run from your panel to your media room.

I’m in Los Angeles. Not sure how many amps that breaker box can handle, but it has spaces for at least another 8 breakers. The run is probably about 60 feet if going straight underneath the house.

New house. That’s easier. Some of the old homes could be at issue with old wiring, etc. (I’m in Menifee, Riverside County).

Are you running big amps?

It’s a newly rebuilt home. All torn down except one wall for the rebuild.

I’m running a P20 into a BHK 250 right now. Will likely move to BHK 300 monos after moving in.

I don’t have anything running that kind of juice. My P12, and P5 don’t even getting worked out with my gear. You’re smart to do up front though. Your electrician should be able to get you dialed in. Don’t forget the ethernet cabling. I had to retrofit Cat 6 cabling across the house. The main breaker switch should be labelled with the service capacity.

Yeah, figure it’d be a pain to do later. Easiest to do this while the house is empty. Fortunately, the whole home is pre-wired with coax and cat 6.

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This is impossible to discuss with the information provided but I’m going to make a guess and throw out some info. It’s likely a 200A-240V-Single Phase main electrical service. The 2-100A-2P breakers likely feed sub-panels (garage, basement, pool house, etc.). Sounds like it’s a house with lots of electric appliances? The 50A-2P and 40A-2P breakers would be feeding condensing units, electric ranges, maybe a instant hot water heater…

You’re going to want at least one 20A dedicated circuit for your audio system. IMHO a single 20A will be more than enough but others here have different ideas. I would run a dedicated 20A-1P circuit with #10 (don’t go bigger, they will not fit the lugs on the breaker or receptacles - you could use #8s on the breaker and pig tail to #10s or #12s at the receptacle). At some point, those are large wires to install in a standard junction box. Heaven help you if you buy solid #8s as opposed to stranded. Also, 3#8s require a 3/4" conduit (if you live in EMT land).

I would run a dedicated hot, neutral and ground. Keep in mind, if you want a truly isolated ground, an isolated ground wire is required between the main panel, all sub-panels and the final branch circuit, and a true isolated ground bar in the sub-panels (they sit on rubber isolating feet). This is rarely done correctly in a sub-panel configuration.

One last thing, a disclaimer. All wire sizes listed above assume copper wire and THHN/THWN insulation. I live in an all EMT world (no Romex or NM: Romex is the brand and NM is the generic designation).


Have the electrician install 2 separate dedicated 20 amp lines.


But use #10 wire. I believe it will sound better than #12 wire.

This advice is spot on. Two 20 amp breakers each with 10 guage wiring to hospital grade 20 amp outlets would be my recommendation. If the distribution panel needs replacement go witg Square D QO series.


Good advise. Get the grounding right at the source & you have a good chance at dead silence (no ground loops or hum) in you listening room.

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So it’s looking like…

  1. 2x 20A circuits with 10AWG wiring
  2. Fully isolated grounds from main box to outlet (star configuration from main with isolation through to outlet)
  3. Hospital grade outlets

Should the two outlets have separate grounds?

You want star grounding, ei.e. single point grounding, No seperate grounds as it will cause circulating currents in the ground and increase the noise level.

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So based on this and what amsco15 said – a star ground from the main box, but fully isolated along the way to the outlet.

Yes, don’t daisy chain the ground. Consider it as two separate feeds, one to each outlet direct from the distribution panel. I assume you are not doing this work yourself, correct?

Definitely not!

I live in Hong Kong, where 230V AC is the standard. When I renovated my apartment, I had 3-phase AC installed - extremely beneficial for my audio system!