Trouble Shooting Receptacle

Status
Not open for further replies.
Location
Denver, CO
Occupation
Electrical/Lighting Engineer
My brother has a standard NEMA 5-20R in his home that takes two circuit breakers to shutoff. I had him take the receptacle out of the wall and there is only a single hit, single neutral and single ground in. I had him measure the potential with both breakers on, its 120V, and with one breaker off its 120V, switch the on/off breakers 120V, both off 0V. Any ideas how this thing is wired? I have never in my 15 year career seen a duplex outlet take two circuit breakers to turn off and it not be a 240V.
 
Location
Denver, CO
Occupation
Electrical/Lighting Engineer
Duh, of course thats why its not 240V I totally overlooked that. So next it seems to me this is a code violation. I can spend some time diggin in but if any of you know right off the bat shout.

If there is a short can you gurantee both breakers trip?
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
181205-1357 EST

Quite obvious as ActionDave said. This is what can be called a logical inclusive "or" circuit.

You need to visually try to trace where the cables go and where they might be connected together. If that does not work, then I may have a suggestion of how you could magnetically detect where the circuits travel.

.
 

growler

Senior Member
Location
Atlanta,GA
I can spend some time diggin in but if any of you know right off the bat shout.

If there is a short can you gurantee both breakers trip?

There is no way to know exactly where it is but you can get some information by shutting off the breakers one at a time and determining what is on that circuit. If there are lights on the circuit then a good place to look is in the switch box for stair ways. Often there will be more than one circuit there because there will be switches for other lights ( hallways and so forth ).
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
There is no way to know exactly where it is but you can get some information by shutting off the breakers one at a time and determining what is on that circuit. If there are lights on the circuit then a good place to look is in the switch box for stair ways. Often there will be more than one circuit there because there will be switches for other lights ( hallways and so forth ).

With either breaker on, there will be 120 volts from one breaker terminal to the other. Both breakers will have to be off to see what the circuit powers.

I ran into this once and it was no fun. We ended up re-feeding that circuit because we never found the junction. It could have been buried in the wall. We checked every box, this was a very small house.
 

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
Had this problem left the neutrals hooked up removed and wirenutted one hot. Could never find the box, old house every type of wiring ever thought of was in it.
 

JFletcher

Senior Member
Location
Williamsburg, VA
The easiest and quickest place to check for an illegal junction is the panel.

5 - 20r in a residence is a pretty good indication that a homeowner or handyman wired it. I say check the panel since that's the obvious place to tie together two circuits, one that is overloaded with one that is not and split the load across two breakers.

This is obviously not legal, however I have seen it done a handful of times...

other obvious place to look is the nearest convenient place that would have two circuits possibly in it, like a 2g+ switch box.

Eta: I almost forgot... If both of the wires originate from a mini tandem, somebody has improperly tried to create a multi wire branch circuit. In that case the circuit will be double fed.
 

Adamjamma

Senior Member
Why would a 5-20r be a sign that a handyman wired it if you need 20 amp circuits in a kitchen? I mean, I use it in kitchens and garages. But, just wondering? Is it because most appliances only need the 5-15 so why spend the extra 22 cents?
 

JFletcher

Senior Member
Location
Williamsburg, VA
Why would a 5-20r be a sign that a handyman wired it if you need 20 amp circuits in a kitchen? I mean, I use it in kitchens and garages. But, just wondering? Is it because most appliances only need the 5-15 so why spend the extra 22 cents?

It is because dedicated 20 amp circuits on 120 volts are practically non-existent and not required in residential settings... Also, non electricians think that a 20 amp circuit requires a 20 amp receptacle.


In commercial work it is quite different, however probably 95% of the 5-20r I've run across in residential work were handyman or homeowner hand add-ons.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
191205-1710 EST

Someone raised the question about the tripping of two breakers in parallel.

At what current the circuit will trip will depend upon the distribution of current between the two breakers.

Suppose that all current was thru one breaker, then 20 A causes trip. Obvious that is only an assumption not likely in a reall situation. Change the assumption to the current is equally distributed between the two breakers, then trip occurs at 40 A. Once a first breaker trips, the second will immediately trip.

.
 

Chamuit

Grumpy Old Man
Location
Texas
Occupation
Electrician
Do you have a toner that you could trace the circuit with? Find the possible boxes that the circuit ran through.
 

Adamjamma

Senior Member
It is because dedicated 20 amp circuits on 120 volts are practically non-existent and not required in residential settings... Also, non electricians think that a 20 amp circuit requires a 20 amp receptacle.


In commercial work it is quite different, however probably 95% of the 5-20r I've run across in residential work were handyman or homeowner hand add-ons.

I use 20 amp in kitchens and garages because I have seen a few 15 amp outlets melt..usually when running a blender or a big toaster or a big drill on an extension cord, but...
Of course, that was the old style outlets and not the new tr or decora style outlets. Someone told me they have never seen a 15 amp outlet melt that was properly torqued and another told me he saw one handle 28 amps so he did not think I needed to worry about it.
But, If we can just put 15 amp outlets on 20 amp circuits and not worry about it, why can we not put fifty amp outlets or 45 amp even on 60 amp circuits? I mean, the outlet should hold up just fine, but yet we yell about it. Yet 15 amp on 20 amp circuits, even on 20 amp dedicated circuits, is ok. Perhaps we just need the manufacturers to stop making the 15 amp and make them all 20?
 

JFletcher

Senior Member
Location
Williamsburg, VA
You can put a 50 amp range receptacle on a circuit anywhere from 40 to 50 amps. There are also exceptions for things like welders.

15 and 20 amp duplex receptacles have the same pass-through current, only the plastic faceplate and prong configuration are different.

You cannot put a 15 amp Simplex receptacle as the only receptacle on a 20 amp circuit, and the same rule applies for a 20 amp Simplex receptacle on a 15a circuit.

If there is more than one outlet, like a 15 amp duplex receptacle, you can put them on a 20 amp circuit.

I, too, have seen many 15 amp receptacles burn up on a 20 amp circuit, however most of them were due to back wiring / backstabbed wires, loose side screws, or a receptacle that is so wore out that does not make adequate contact with the prongs on the plug going to the device.

And yes, the 5 - 20r receptacles tend to be a little more expensive, and since they are internally identical to the 15 amp receptacles (and cannot be used on a 15 amp circuit), most contractors are going to use the 15 amp receptacles everywhere.

The extra price and not needing to use a 5-20 r is why I say that most of them in a residential setting are installed by non electricians.

To that end, if you cross connect is not in the panel, it is likely inside of a switch box that can handle two circuits in, and at least a switch leg and a circuit out. In my experience, a double fed circuit is never cross connected inside of a single gang box.(eta: in an older home, it could be inside of a ceiling light box)
 
Last edited:

JFletcher

Senior Member
Location
Williamsburg, VA
Had this problem left the neutrals hooked up removed and wirenutted one hot. Could never find the box, old house every type of wiring ever thought of was in it.

This will certainly work, however it does still leave a circuit with parallel neutrals, and if the breakers are of different amperages, it would be wise to remove the wire from the higher amp breaker. I do not consider the parallel neutral in this case a problem since one of them can handle the current.
 

jeremysterling

Senior Member
Location
Austin, TX
This will certainly work, however it does still leave a circuit with parallel neutrals, and if the breakers are of different amperages, it would be wise to remove the wire from the higher amp breaker. I do not consider the parallel neutral in this case a problem since one of them can handle the current.

Seems like the neutral would be more like a ring rather than parallel.

I would prefer not to leave the ring.
 

Santa49

Member
Location
Pittsburg, ks
Occupation
retired
Santa49

Santa49

If all efforts of locating where the two ungrounded conductors are tied together or touching each other I would then splice them together in the breaker box with wire nut and pigtail them to a single 20 amp breaker. Could also do the same with the grounded conductor. (pigtail and land on neutral bar) It may not "fix" the problem, but will make the symptom go away.
 

JPinVA

Senior Member
Location
Virginia
I guess I'l ask the question with the obvious answer. The two breakers are same phase, yes? From what I read above, they would have to be. But I gotta ask. I'm not looking for an answer of "Well, they must be same phase". I"m looking for an answer of "I looked in the panel, and YES, they are same phase".
 
Status
Not open for further replies.
Top