Plugging in an Amplifier

[gcmarshall]

What do I need on/in my wall as far as an outlet/circuit is concerned to plug in your average power amplifier. A lot of the power amplifier manuals I have read indicate the need for a 20 amp circuit? What does that mean in layman's terms? Do I need a 3-prong wall outlet? Would that be a standard 3-prong wall outlet or does the ground plug need to be one of the "flat" receptacles? Does the wall outlet for the amp need to be on its own circuit and how do I know if it's a 20 amp circuit?

 

[t3031999]

20 amp outlets are 3 prong with the neutral (left) prong it a sideways T shape.
15 amp outlets can also be connected to a 20 amp circuit if there are more than 1 outlets on the circuit.

The best way to find out if an outlet is on a 20 amp circuit is find which circuit breaker shuts the outlet off. The rating of this circuit breaker is what determines if a circuit is 15 or 20 amp.
If the outlet you need is on a 20 amp circuit then you just need to make sure it has a 20 amp outlet for your amplifier. You may need to replace the circuit breaker
If the outlet is not on a 20 amp circuit you can replace the circuit breaker with a 20 amp breaker. This can be a dangerous job and you should have a certified electrician help you.
If you do the work yourself: plan, turn off all power before working, and please be careful, 120VAC is not a toy.

It's best to have the amplifier on it's own circuit, but if you have to share the circuit with something here are some suggestions:
1. Don't share a circuit with inductive motors (i.e. refridgerator, dryer, fans...)
2. Don't share a circuit with fluorestent lighting...
3. Try not to share the circuit with any lighting.

the first 2 are to avoid line noise, the last one is a safety concern. If your amp trips a breaker, you will still have lights to see where you are going.

Be safe and have fun.

EDIT: sorry forgot to answer in layman's terms what a 20 amp circuit is.
the rating of a circuit is the amout of power that can flow through the wires. If your devices draw more than 20 amps it will trip a breaker, or blow a fuse.
It's basically a limiting value for electric current.

 

[jaxvon]

A "20 amp" circuit refers to the amount of current the circuit can handle, not power. Recall that Power = Volts * Amps (amps are current). Power is measured in Watts, potential difference is measured in Volts, and current is measured in Ampres.

 

[t3031999]

but since the voltage in house wiring is pretty much fixed, the power changes are directly proportional to the current.
And since outlets and circuit breakers are rated for both a current and voltage rating, saying they are rated for a certain amount of power is technically correct.

But you are right, my wording was not quite correct. I was trying to portray a certain concept in lay terms and not get into the specifics.

 

[jaxvon]

I definitely agree. But just in case he would remember all this stuff, I don't want to pass on BS knowledge. Always best to play it safe.

 

[mtrycrafts]

And since outlets and circuit breakers are rated for both a current and voltage rating, saying they are rated for a certain amount of power is technically correct.
.

I don't think you are correct in this case. Breakers are rated to a max voltage. But, it is primarily a current device and that is what trips it, no?

A breaker on a 120V branch can also be used on a 240V branch, hence, power rating is different, right? Then, it is not very useful as it has multiple ratings.

 

[t3031999]

Electricity coming into a house comes in as 2 hot wires and a neutral.
The voltages of the 2 hots are on opposites sides of the neutral because of the way the step down (from 7000v) transformers work.

These 2 different hot wires are the 2 different poles in a circuit breaker box. They are both 120v but have opposite polarity. A 240v circuit breaker is simply attached to both lines and the voltage between then used.

So basically what I am saying is that circuit breaker boxes are designed to handle 120v difference from the ground, and therefore ALL house wiring is
120v rated.

 

[QED]

Somebody please correct me if I'm wrong, but my understanding is that the entire circuit including the breaker, outlet and the wire must be rated for 20 amps for it to be a 20 amp circuit.

As far as I know, this means making sure that you have at least 12 AWG wire for a 20 amp circuit and not 14 AWG which is commonly used for 15 amp circuits.

 

[PENG]

Of course you are right, 12 AWG wire for a 20A and 14 AWG for 15A, assuming you are talking about copper wire. No one is suggesting anything different here, right?

 

[QED]

Actually, t3031999 posted the following:

"...If the outlet is not on a 20 amp circuit you can replace the circuit breaker with a 20 amp breaker..." with no mention of the wire gauge issue.

We all need to be careful about partial or incomplete advice, especially when it comes to electricity.

 

[PENG]

Actually, t3031999 posted the following:

"...If the outlet is not on a 20 amp circuit you can replace the circuit breaker with a 20 amp breaker..." with no mention of the wire gauge issue.

We all need to be careful about partial or incomplete advice, especially when it comes to electricity.

Thanks, I missed that post.

 

[mtrycrafts]

Of course you are right, 12 AWG wire for a 20A and 14 AWG for 15A, assuming you are talking about copper wire. No one is suggesting anything different here, right?

Not only copper but a certain class of insulated copper. THHN, a higher temp insulation may be smaller than the 12 ga for 20A use.

 

[mtrycrafts]

So basically what I am saying is that circuit breaker boxes are designed to handle 120v difference from the ground, and therefore ALL house wiring is
120v rated.

If you look at the wire installed in houses, they are rated to 600V. I checked a breaker, no specific voltage rating on it.

 

[mtrycrafts]

Somebody please correct me if I'm wrong, but my understanding is that the entire circuit including the breaker, outlet and the wire must be rated for 20 amps for it to be a 20 amp circuit.

As far as I know, this means making sure that you have at least 12 AWG wire for a 20 amp circuit and not 14 AWG which is commonly used for 15 amp circuits.

Not totally correct. Check your kitchen wiring. You need at least 2 circuits that are 20A rated, yes, the wire is 12ga because of it, but then check your outlets. Do you see one with a T slot on one side? I doubt it, so that is only a 15A outlet. I have 20A outlets though, I put it in.
The kitchen has the 20A circuit because of the loading you can put on one circuit, up to the limit of 20A.

So, you need the wire to match the breaker but not the outlets.

 

[t3031999]

Sorry about not mentioning the 12 ga wire for 20 amp outlets.
I always use 12 ga or larger in all of my installs, regardless the amperage of the circuit, and I completely spaced out the fact that for 20 amp it would be illegal to use anything smaller.
Thanks for catching that.

 

[gcmarshall]

Thanks everyone for the info! I only wish I knew as much about this stuff in order to return the favor.

So, I checked my breaker box. My living room, where I would install an amp (let's say a Rotel RMB-1095, for argument sake), is on one 15 amp circuit. In other words, it appears that my wall outlets and lights in the living room are on one single 15 amp circuit. If I were to install the RMB-1095, it would be added to that circuit.

I am assuming that since my breaker is 15 amp and that since my house was built with the cheapest materials in the housing business, that my electrical wiring is matched to the 15 amp breaker (ie, it is not thicker than it needed to be).

Rotel tells me they "recommend" a dedicated 20 amp circuit for that RMB-1095. Given my situation above, I think I would be taking a bit of a risk, if not a safety risk, then certainly a risk that I might trip my breaker everytime I try to use a $2,000 product. That, of course, would drive me nuts.

I believe I am correct in further assuming that changing my outlet to a 20 AMP plug, while leaving the existing wiring and leaving the 15 amp circuit breaker is not a real solution, only a partial solution that will not guarantee a trip-free experience.

Or, would I be OK with a 20 amp outlet, but keeping the existing wire and exisiting 15 amp circuit? Our house has no basement or crawl space, so re-wiring is out of the question.

 

[jaxvon]

Installing a 20-amp plug without using 20-amp rated romex and a matching breaker would be a waste of your time and money.

On the plus side, as long as you aren't using mega-wattage halogen lights, you shouldn't have any issues with tripping the breaker, even at loud levels. Even at rediculously loud listening levels you're only going to be drawing 50-70wpc with moderately sensitive (90dB) bookshelves.

However, because your amp will be on the same circuit as your lights, I highly recommend a quality power conditioning unit like a Furman, Tripp-Lite, Panamax, or if you can get a good price on it, Monster. This is an absolute necessity if you have any lights on rheostats (variable resistor switches). Variable resistors + halogen lights = Loud, Obnoxious Buzzing in the electrical lines. Without a good line conditioner, you will hear this noise in your speakers.

 

[hchytd]

Okay, okay...

For the rest of us, can y'all just send a link to the type of power strip/surge protector you advise we use with our good A/V receivers, powered speakers, and plasma TV (that is affordable)?

Thanx

 

[gcmarshall]

JAXVON,

Thanks. I don't know, but might the RMB-1095 have a horizontal plug on it that requires the 20 amp outlet's matching horizontal receptacle? I currently have an e-mail in to Rotel about this. Will report what I find out.

 

[jcPanny]

Power protection for A/V

Audioholics includes the triplite HT10DBS for <$80 on its recommended system. It will filter the AC lines, issolate each outlet, and provide surge protection.
For about $300, check out the APC H10 Power Conditioner/Voltage Regulator. Expect to pay a more if you also want battery backup capability.