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nexusteve 09-25-2011 11:56 PM

Is there a meter to measure existing amp load on a given circuit?
My knowledge of electricity is very limited. I've probably not even asked the question correctly, but I will try to explain what it is I am looking for. My work requires me to plug in a variety of machines at residential homes in order to complete any given job. I have been running into problems trying to figure out what plug(s) belong(s) to which breaker. Consequently, I end up doing a trial and error testing routine that ends with my tripping the breakers multiple times before finally figuring it out.

I've seen the testing device at Home Depot where I can plug in a transmitter into the outlet and then go to the breaker box to trace out which breaker that particular plug belongs to. What I'd rather be able to do is plug in a machine (lets say an 8 amp machine for this example) and then probe the nearby outlets to get some kind of visual reading which shows me that the two plugs are or are not on the same circuit. For instance, if they were on the same circuit, I would see that the 8 amp machine drawing power from that same circuit. Hope this makes sense, not sure I am phrasing it right.

Is there any meter or device that can do this?



forresth 09-26-2011 12:11 AM

to measure current, you have to access the wire that the current is running through. an empty outlet has no current running through it.

Just Bill 09-26-2011 06:22 AM

There are clamp on ammeters, that clamp around the hot conductor. A standard ammeter has to be inserted in series with the load.

AllanJ 09-26-2011 07:02 AM

You could plug in a medium sized (in terms of current draw) appliance somewhere and use the clamp on ammeter on the various circuit wires attached to the breakers down in the panel to see which one has the load.

Antoher common method to find out what receptacles are on what circuits is to turn on one breaker at a time and test the receptacles for power using portable lights (no minimum wattage). This method is usually faster than starting at a receptacle and making the measurement down at the breaker panel.

Using the transmitter (toner kit) you can also catch several receptacles in a row using the receiver whether you put the transmitter probe into a receptacle or hung it on a wire in the breaker box (flip off the breaker so the tone signal doesn't leak into receptacles throughout the house).

In most cases a few receptacles will be overlooked in the first go round and need to be checked one at a time.

If you routinely trip breakers while performing the overall task you described, then your method is the worst possible method for doing that task.

dmxtothemax 09-26-2011 07:59 AM

Measuring currant flow in a circuit can be done,
with an ammeter, either clamp on or hard wired,
But it is not recommendded for inexperienced people,
Because it involves breaking into the hot line.

But what are you really tring to do ?
Sounds like you are tring to identify what is on what circuit?
As this is much easier to do.

Whats your issue / problem ?

mpoulton 09-26-2011 08:11 AM


Originally Posted by AllanJ (Post 736083)
If you routinely trip breakers while performing the overall task you described, then your method is the worst possible method for doing that task.

LOL, yeah. There has to be a better solution for whatever you're doing. What is the equipment and what are the power requirements?

a7ecorsair 09-26-2011 09:07 AM

When asking for ideas and advice, it helps those responding to understand the issue and problem. What you are asking to accomplish is somewhat strange. You say you go into residential homes and run a variety of equipment but you need to identify the supporting breaker.
If I were to guess, I'd say you are in the home health care business but why do you need to identify the breaker that supports any particular receptacle?

nexusteve 09-26-2011 10:21 AM


Originally Posted by dmxtothemax (Post 736113)
But what are you really tring to do ?
Sounds like you are tring to identify what is on what circuit?
As this is much easier to do.

Whats your issue / problem ?

Thanks for the responses so far guys. We are in the water damage remediation business. On some jobs we run air movers (3 amps each), dehumidifiers (8 amps each), heaters (12-48 amps each), and other specialty equipment designed to dry different materials. Many jobs require 10-15 air movers, 2-3 dehumidifiers, 1-2 supplemental heaters, etc.. So my problem is I have to set up all of this equipment near the source of the loss and then begin the search for electricity to feed them. Many times the breaker box has no labeling so I am just plugging the machines in as much of a logical manner as possible, but right now it's all guess work. Often I guess wrong and I end up tripping the breaker.

Some of the suggestions will definitely help in sorting this out, it just would be much easier if I could somehow identify which plugs belong to which breaker without having to go to the breaker box.



forresth 09-26-2011 10:36 AM

Sounds like you are just asking for a shock with extension cords and multiple unprotected circuits working on soggy carpets.
For safety reasons and convenience, you might want to get a GFI breakout box that you would plug into a 4 prong range receptacle or generator.

AllanJ 09-26-2011 12:23 PM

The correct way is still to do an inventory of the various circuits and the groups of receptacles they serve.

Using the method of turning off all except one breaker and then testing to see what receptacles are still live will work without having to open up the breaker box (other than opening the "door".

Using a toner kit (transmitter) can be done without opening up the breaker box.

Using any kind of ammeter does require opening up the breaker box and/or other things like junction boxes.

And you will likely need to run extension cords, for example from a bedroom and its circuit for one dehumidifer, from the kitchen and one of its circuits for one heater, etc. all needed in one place such as the living room or the finished basement.

dmxtothemax 09-26-2011 06:41 PM

Fitting any type of ammeter is not an easy thing,
So it is not easily and safely done.
You would be better off using some sort of
remote circuit identifier system.
Such as a toner transmitter.
If you use two people and a cheap two way radio system
this could be easily and safely done.
The only cost is some time..

So the answer to your original question is NO.
There is no easy and safe way to monitor currant flow.
There are many ways it can be done.
But not easily and safely,
as all require breaking into the hot lines,
and this would require an electricain
if it is to be done safely.

mpoulton 09-26-2011 10:43 PM

I second forresth's recommendation. The most reliable solution is to run your own temporary distribution. Make up a set of distribution boxes and cables with GFCI protected receptacles that plug into standard range and dryer receptacles. Almost every house has those. Each 30A dryer receptacle is good for 7200W, or the equivalent of 4 standard 15A circuits. Each 50A range receptacle is good for 12,000W, or 4-15A circuits plus 2-20A circuits. Most houses have both. Together, that's usually more power than all the other receptacles in the house combined. You also have 240V power available for heavy duty heaters and dehumidifiers.

frenchelectrican 09-27-2011 01:22 AM

I see you are running a bussiness for water damage remediation

There is couple soluation I can suggest is one is have a spider box

There are few diffrent verison on hand the best place you can check it out is the rental place they should have couple diffrent verison on hand

This verison is mine which I used in France pretty often.

If that house have electrique stove then it will not be a super major headache to use the spider box due it allready rated for 50 amp supply but if not then the best answer have a electrician assit you on this one.

Oh yeah the other thing you should be aware is that if you see or supect water damage at the switch or receptale even breaker / fuse box the best thing is stop right there and have electrician assist you on this one with water damage on electrical equiment they will know excat what to do with it.

{ most case we will replace the breaker box if water damage show up ditto with switch and receptales as well }

For the power useage on your device which you normally used on the jobsite can get pretty wild listing so let moi run this listing for you.

Air handlers 10 to 15 units 30 to 45 amps
Dehumidfiers 2 or 3 units 16 to 24 amps
Electrique heaters 1 or 2 units 12 to 48 amps

Total drawage will be run from 58 to 117 amps so you will have to use the judgement call on the house with smaller electrqiue service in there { 60 /100 amp class } the 200 class useally not a issue however for all class I mention the key item is any extra space for tempory useage that will be determed by electrician to tell you the final answer on that.


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