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Discussion Starter · #1 ·
Hi,


I am builiding a house with a small media rm (14 X 14) and requested installation of 30 amp dedicated circuit to run 50 inch plasma, audio visual equipment (for whole house audio/video), receiver, dvd player, tivo, cd changer, amplifier...bottom line usual entry level stuff.


Instead of a 30 amp circuit a 20 amp was installed. The builder is willing to tear down walls in order to revise this if necessary.


I have no knowledge in this area but a large capacity circuit was highly recommended in case I wanted to add/upgrade components in the future. Should I insist on a 30 amp circuit or is a 20 amp OK?


Would appreciate any prompt advise as I am two days away from closing and would need to readjust plans if circuit would be an important consideration.


Thanks very much for any help,


Rose
 

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20 Amps is fine for what you have now. No way to tell if it will be sufficient in the future. Depends on the equipment you buy. There are many amps, for example, that require 15+ power lines, which would not leave much for the rest of the equipment.


If you requested a 30 Amp line (and he charged you for a 30 Amp line), I would ask for him to re-do it, or to add a second 20 Amp line. Perhaps he could do that without tearing down the walls.


Steve
 

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A 30 amp line is useless unless it goes into a sub-panel. A 20 amp circuit should be fine, 2 20 amp circuits would be better. You cannot plug 15 or 20 amp equipment into a 30 amp circuit directly.


Paul Riordan

Riordan Brothers Electrical Contractors
 

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I agree with Steve that a 20A circuit will suffice. Allowing for the code safety factor, you can run 1920watts of continuous power draw. A rough guide is adding up all the POWER CONSUMPTION wattages listed on the metal plates located on the rear of each piece of gear.


But there may be a luck-out element to this: The opportunity to have the electrician install one more 20A (12AWG wire) ckt . He can run one or two more wallboxes and you can place one nearer to where a sub might be plugged.


While some may argue the merits, the usual suggestion is to wire the second circuit on the same phase or side of the breaker box as the first.


Fingers crossed, the introduction of two 120V ckts will not present an opportunity for ground loops. Since the latter usually are system equipment dependent, it's difficult to forecast.


I'd go ahead and pay a little more for an addl circuit.


bill
 

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To expand on Paul's post, you can use wire suitable for a 30-amp circuit (#10) on a lower-capacity breaker. The breaker is what determines the circuit rating, and then appropriate receptacle(s) are chosen to match. The one exception is that, except for single (not duplex) receptacles, 15-amp rfeceptacles may be used on 20-amp circuits.


Rose, the electrician may well have used the #10 wire that was requested, but merely installed a 20-amp breaker. If this is the case, you have a couple of options. You can have a 2-circuit subpanel installed, like Paul suggested, and have two 15- or 20-amp circuits fed from it.


The other is just leave it as is for now, and as long as you don't trip the breaker, you're okay. Just remember to get your money back for the improper installation, pointing out that you will have to pay a lot more later if the need arises. However, between you and me, I don't think you'll ever exceed the 20-amp circuit's capacity.

Edit:


Oh, one more thing: Bill mentioned wiring two circuits to the same phase. This is okay only if two separate cables are run, and must never be done using a shared neutral; that would require using opposite phases. Which side of the panel is irrelevant to phases; adjacent spaces assures using two phases.


Okay, another thing: Bill, if you go into 'edit', there is a 'delete post' option.
 

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Quote:
Originally posted by norcalbill
A rough guide is adding up all the POWER CONSUMPTION wattages listed on the metal plates located on the rear of each piece of gear.
If I do that I end up with 2880W for the power amps alone, although actual consumption is just 200W at idle, and 1300W with sine waves driving them to 100W/channel into 8 Ohm loads. I don't play 105+ dB test tones through all eight speakers at once so even the later number isn't realistic.
 

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Quote:
Bill mentioned wiring two circuits to the same phase. This is okay only if two separate cables are run, and must never be done using a shared neutral; that would require using opposite phases.
Larry,


Could you expand on this please. I understood this to be exactly what many on the forum were doing (running 3 conductor Romex for 2 in-phase 20 amp circuits).


Thanks for the help.


Patrick
 

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bumping my own question. Can anyone confirm that I cannot hook two conductors on one phase and share a neutral?


I'm about to land 2 of my three circuits for the HT (equipment and projector circuits) and planned on running the two conductors off a skinny and sharing the neutral. Is this safe? Is it not desirable for some other reason?
 

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If you connect the two hots to ONE breaker, then the neutral is protected. If you have two hots on opposite phases (the correct way), then the neutral will only carry the difference current, which can not exceed one breaker's rating.


If, however, you connect the two hots to separate breakers on the same phase, then the neutral could be subjected to TWO circuits' worth of current, which can overload the neutral by double its capacity. Not good!
 
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