How many appliances can I safely run on a single circuit?

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  #1  
Old 05-17-04, 10:56 AM
Aegis
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How many appliances can I safely run on a single circuit?

I've two new window a/c units, both need 7.6 amps, use 835 watts, & run at 115 volts. When plugging these things in, I only need concern myself with the amps, correct? Like if I've got these both plugged into a single 15 amp circuit, it's probably gonna be flipping off all the time, and should therefore try to put them on separate 15 amp circuits or replace the 15 amp breaker with a 20 amp breaker?

And the above prompts the question, is there a way to measure the load on circuit breaker using a volt-meter (or whatever they're called, I know the nifty-lil device I have can measure amps), or do I have to look at all the things plugged into the circuit and sum up their individual draws to figure it out?
 

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Old 05-17-04, 11:26 AM
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Yes, putting both on the same 15-amp circuit (even if nothing else was on that circuit) probably won't work, especially on a hot day.

But of course you cannot replace the breaker with a 20-amp breaker unless your fire insurance is for more than the replacement value, and you have really good fire escapes.

There's no good way to measure the load on a breaker. For one reason, you could only measure the instantaneous load and load varies over time as things start up and shut down. If this is an existing 15-amp circuit, it's a safe bet that it was designed for the loads already on it. But you can shut off the breaker, find out what went dead, and look at the specs for those things. Of course, receptacles are an unknown quantity since somebody could come along at any time and plug the vacuum cleaner in there.

I suggest new circuit(s) for your new air conditioners. If you have space in the panel, it's not a big deal to add new circuits.
 
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Old 05-17-04, 12:15 PM
Aegis
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But doesn't that entail running new wires...through the walls?
 
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Old 05-17-04, 09:44 PM
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Yes, it requires running new wires in the wall. It's done thousands of times every day. It's a pretty routine process.
 
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Old 05-18-04, 12:38 PM
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Aegis,

I believe John is trying to be polite. I won't bother. there is no way you should ever even consider running both of those units on one 15 Amp circuit unless you live in Alaska. Even a 20 Amp circuit is pushing it for my tastes, but it would meet code. And you can't just put a 20 Amp breaker on a 15 amp circuit UNLESS the wire happens to be 12 gauge. AC units run long and hard on hot days and tend to heat up a LOT. Most electricians that I've met want a dedicated ciruit for every window air conditioner. If you plan on being in your current location for a long time this is well worth the investment.
 
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Old 05-18-04, 06:33 PM
paulp412
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Help me wire my home

"Yes, it requires running new wires in the wall. It's done thousands of times every day. It's a pretty routine process."

I'm ALL ears. I'm gonna try to wire my home from scratch for the very first time
 
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Old 05-18-04, 08:39 PM
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It's routine, but it's not one size fits all. There are a million tricks, and the appropriate trick for one situation can only be decided after studying the site. Many books on home wiring show you a few tricks. If you read them all, you'll have quite a few tricks in your bag.
 
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Old 05-21-04, 09:34 AM
Aegis
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Routine is fairly relative...writing a book is routine for a well-published author, building an aircraft is routine for Lockheed-Martin, and I venture that running wire and patching up the resulting wholes in the finished wall is routine for an electrician, but not, however, for a ignorant cuss like myself.

hehe, I appreciate the candor though. I (we, actually...I'm putting this in for my grandmother) have resolved to place one of the a/c units in another room, supplanting an older, larger one, that, for some reason, is no longer adequate...no idea why.

Anyway, Paul, if you're going to be doing all that wiring, you might also think about running some Cat5, if you think you might ever have a home network for sharing files, printers or internet access. A hard-wired solution is faster, more secure, and obviously gives you no problems with signal strength (unless you're making more than 100 yard runs...at which point EMI & attenuation become concerns, but that's unlikely if it's in-home ). Best of all, it's routine.
 

Last edited by Aegis; 05-21-04 at 03:00 PM.
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Old 05-22-04, 07:29 AM
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Question

Originally Posted by paulp412
"Yes, it requires running new wires in the wall. It's done thousands of times every day. It's a pretty routine process."

I'm ALL ears. I'm gonna try to wire my home from scratch for the very first time
Is this a new home with the walls open and unfinished or are you about to rewire an existing home.
--
Tom Horne
 
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