what is the easiest way to determine the amps

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  #1  
Old 03-21-05, 10:44 AM
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what is the easiest way to determine the amps

Okay, my electrical "lack of knowledge" (read ignorance) is going to show here.

What is the easiest way to determine the amps on any particular outlet.

I know the one way is to plug a small light in and go to the breaker panel and turn them off one at a time with someone else telling you when it goes out. The amps are marked on the circuit breaker and you have your answer.

However, the panel is downstairs and all the outlets I want to check are up and I am doing this while no one else is home (they are no help anyway)...

Is there a device that can plug in like the ground testing plug-ins that I have seen? I mean like a cheapo GFCI test device with orange and red lights for normal 110v outlets. Is there something that will specifically say whether an outlet is 15 or 20 amp?

Thanks,
Pete
 
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  #2  
Old 03-21-05, 10:56 AM
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You should already know what circuit breaker controls each and every receptacle, light and appliance in your house. If you don;t know this (and you apparently don't) then you need to figure this out. This information could save your life or someone else's life some day. Please spend a couple of hours and completely map out your house.

As for the question you are actually asking, you can easily differentiate between a 15 amp and a 20 amp receptacle by looking at the receptacle itself.

15 amp receptacles have two parallel slots for the plug to connect to. Newer 15 amp receptacles also have the round or D shaped hole for the ground lug to fit into.

20 amp receptacles have a sideways T shaped slot in place of one of the parallel slots. A 20 amp plug has two terminals that are perpendicular to each other.

Because of the T shaped slot, a 20 amp receptacle will accept 15 amp and 20 amp plugs. A 15 amp receptacle will only accept 15 amp plugs.

However, do not attempt to determine the size of the circuit by examining the receptacles. It is allowed and quite common for there to be 15 amp receptacles on 20 amp circuits (in the US anyway). In fact, many houses in the US are built without any 20 amp receptacles, although any new ones built will have several 20 amp circuits.
 
  #3  
Old 03-21-05, 11:02 AM
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thanks for the advice. some of the circuit breakers are labeled but not all of them. we just bought the house a few months ago and hadn't had a reason to check them until just recently.

I will need to get one of the kids to help (once we find the FSR radios).

I saw some amp probes but if I can find the information without spending money...well that is the goal.

thanks again,
Pete
 
  #4  
Old 03-21-05, 11:32 AM
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The probes you are talking about are tricky to use, and won't help you anyway. They measure current. They will tell you how much current is flowing through a wire, but that won't tell you the circuit breaker size, the wire size, or any of that important information.

Why is it you want to know this information?
 
  #5  
Old 03-21-05, 11:33 AM
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psal2,

Besides the tips racraft gave you for visually identification, remember this is the rating for the device/circuit. That means the maximum amperage allowed.

If you are wanting to identify how much amperage is actually being used in the circuit, that is where an amp probe will help you. It can tell you how much amperage the circuit is actually drawing, regardless of the rating. Of course, the amperage shown should be within the circuit rating. And an amp probe is not a real inexpensive piece of equipment to just buy to find this out.

If you are wanting help in identifying circuits, there is a moderately priced toy called a circuit finder. It is a 2 piece transmitter/receiver device that is easy to use and priced around $30. You chould be able to find it at any blue or orange store if you want to spend a few bux for a little help.

Hope this helps
 
  #6  
Old 03-21-05, 11:42 AM
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Yes, this all helps.

I have a small workshop set up in the garage. Current cheap table saw works fine off what I assume is a 15amp outlet. However, the one I want to get requires a 20amp outlet. So I am trying to determine what is there.

The breaker panel has laundry/garage as 15 amp. The laundry area is in the back of the garage (and yes, this is not a GCFI plug, but it will be soon.)

There are two other outlets but I believe both are 15 amp. Looking in the attic above the garage it looks like there are off different feeds and I was just hoping that one was 20 amp so I wouldn't need to run new wires.

thanks for the info

Pete
 
  #7  
Old 03-21-05, 11:59 AM
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Even if you do have a 20 amp circuit, you will want to a new circuit if this is not a dedicated circuit.

A table saw that needs a 20 amp circuit will likely cause anything else on the circuit to see a voltage drop, especially on startup. This means that lights will dim, a TV might flicker, a radio might drop out for a second, etc.

Whenever you have a high load device, or a workshop tool of any significant load, you should really run a dedicated circuit.
 
  #8  
Old 03-21-05, 12:01 PM
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If the saw requires a 20A outlet, it would be a really good idea to run a dedicated outlet for that saw. The startup current draw of a large motor is huge and would be best served on its own.

Also, laundry appliances are supposed to be on a dedicated circuit so extending that circuit is a no-no, escpecially to a large motor like a table saw. Remember, your washer and dryer both already have large (~10A) motors in them.
 
  #9  
Old 03-21-05, 12:03 PM
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I guess it is time to call in the pros. I have to get an electrician out to do the work, but I will probably do the "circuit finding". Maybe save a little time and money there.

I am not sure how much it is going to cost. Panel is in basement under house, garage is attached to house and there is no easy access to fishing wires that I can see but then again, I don't do this for a living.

Of course, the main is right behind the garage. Can a second box be added there for just the garage or is that overkill? and would fishing be easier and cheaper?

Pete
 

Last edited by psal2; 03-21-05 at 12:18 PM. Reason: more info
  #10  
Old 03-21-05, 04:07 PM
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As for an easy way to ID circuits when you are by yourself.. just plug a small radio into the outlet, turn it up loud enough you can hear it, flip breakers one at a time until it goes off. Turn the breaker back on, listen for the radio to come back on, then turn it off again to verify you've got the right one.
 
  #11  
Old 03-21-05, 06:12 PM
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Well, one outlet in the garage is a 20amp according to the plug. The garage opener and a light are attached to it. When I work on the table saw, it is usually daytime and with the door open, so I might not need to run a separate line to the saw. The dryer is on a 220v and the washer looks like a 15amp outlet.

I am still bringing in an electrician to check on some other work and I will have him look at running a second line to the garage.

Thanks for the advice.

Pete
 
  #12  
Old 03-21-05, 06:21 PM
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What else is on that same 20 amp line to the garage that the openers are on? If you have nothing else on the line, and it is truly a 20 amp circuit, then you can use it for your saw.
 
  #13  
Old 03-21-05, 06:31 PM
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That is the only thing on it. That line looks like it is coming out of the attic and goes directly to the opener. There is another line coming from a different spot to where a light switch is in the laundry area and to a wall outlet on the back wall.

But like I said, I will probably have an electrician check it out.

Pete
 
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