circuit power requirements

Aloha Outlaws; Would someone (I'm guessing Gonk) be able to explain when either a separate power circuit, or a higher power circuit (eg., 20 amps) would be required for home audio. I'm running Axiom M80 surround system, and will be purchasing Outlaw 990 and most likely the 7125. Also, Would the answer be different for a higher wattage amp ? Thanks.

I'd recommend a separate circuit if the one that serves your home theater has too much else on it (my old home was built in the early 50's and originally the living room outlets were on the same circuit as the kitchen, so the home theater, fridge, and microwave were on the same circuit). Others may have a better rule of thumb (I'm thinking particularly of you, hullguy), but my thought is that if your home theater is on an outlet that shares its circuit with other outlets in the room such that you know what the other loads are and they are not significant (a lamp or two wouldn't worry me, for example, but a space heater would set off big alarms) you probably don't need a separate circuit. If you can easily assign a dedicated circuit (new construction or major renovation), I'd do it, but that's not the case for most of us.

A 20A circuit instead of a 15A circuit will give you 2400W instead of 1800W - a nice idea of you have some insane loads like big class A amps, but otherwise just a bit of "current insurance." Keep in mind that the biggest nameplate load in your system is the amp, but that is also the component that is going to be least likely to approach its nameplate rating. Source components (DVD players, cable and satellite boxes, game consoles, ...) probably draw 15W to 40W each. A surround processor would be on the high side of that range, but still negligible. Your TV would be a higher load, but when looking at nameplate ratings for front projectors and large plasmas a few years ago (trying to figure out heat gain to the space) they never seemed to break 300W. An amp will probably have a nameplate rating of up to 1800W (the maximum power available from a 15A circuit) - the 7125 comes in at 1440W. Even with big speakers like those Axioms your amp isn't likely to draw more than a quarter of that for most of its life.

Thanks Gonk
This gets a little complicated! If you are going to have a a dedicated circuit run, you are better off with a 20 amp circuit. You are only supposed to put a load of 80% on a circuit, (12 amps on a 15 amp circuit, and 16 amps on a 20 amp circuit!). This means you really only have 1440 watts available on a 15 amp circuit and 1920 watts available on a 20 amp circuit.

One of the advantages of running all your HT equipment from the same circuit is you are using a common ground and neutral on all your equipment. This should rule out having any ground loops from the power side of your equipment.

I personnaly feel it's best if the electrician puts in 4 plugs instead of 2. Gives more flexibility when plugging things in.

Also, watch out for the current rating on any power strips. Most I've seen are only rated at 15 amps. If you plug one of these in to a 20 amp circuit you've just derated it from 20 amps to 15!

All of the the above is good advice.

My whole system (see sig) rarely pulls more than 6 amps when screaming!

Thanks for the great feedback ! Looks like I'll be able to avoid the call to the electrician and save the money for acoustic treatment for the room. Aloha.

Follow-up question guys. Hope this makes sense - my head is still pounding after last night's Pearl Jam show. I have two components that are higher current draw, the outlaw 7125 and the Axiom EP500 sub. If I understand correctly, one should use a high current MOV surge protector, or I guess a series type like the Brickman. If I go with an MOV, what type of maximum current rating would be appropriate?

I'd probably look at the maximum current draw of the device being connected (1440W or ~12A for the 7125, 675W or ~5.7A for the EP500), although I suppose you could get close to the rating of the circuit breaker (15A) just to be sure you wouldn't starve anything of the available current.

Makes sense, thanks!

A fun tool to use for power measurements is the Kill-A-Watt meter. You can find it off Amazon or other places.

FM, I checked the Kill a Watt. Kind of interesting. Will it also record peak amperage over a period of time ? In other words, to give me an idea of what the combined draw of my high current equipment might pull?