two 240v outlets without power?

[bjammmin]

Just moved into a new house and finding out that both 240V outlets (one in the house for a dryer and one in the garage for compressor, etc.) are showing 0V in any combination of multimeter tests. But measuring voltage across the black/red wires out of the 50A two-pole breaker at the panel shows the full 240V. And flipping the breaker off seems works as intended.

Sure there could be an issue with the wiring in the walls, but it seems awfully odd that both outlets would be out. I'm wondering if the previous owner had some additional switch hidden somewhere. Any other theories?

 

[The Cobbler]

are the receptacles wired at the boxes? just wondering if for some reason they were disconnected

 

[bjammmin]

are the receptacles wired at the boxes? just wondering if for some reason they were disconnected

I did pull the receptacles out from the wall and measured voltage across the wires themselves. Still read 0v. I also tried other 110v outlets just to be sure the MM was working. Good thought though...

 

[justsam]

Are there one or two breaker sets that are two pole?
One set for the dryer and one set for the compressor?
Could the wiring for the dryer have been rerouted in some manner for the compressor?
Do you measure anything from either hot lead and ground?

 

[bjammmin]

Are there one or two breaker sets that are two pole?
One set for the dryer and one set for the compressor?
Could the wiring for the dryer have been rerouted in some manner for the compressor?
Do you measure anything from either hot lead and ground?

I only see a single two-pole breaker set (50a) in the panel. All the other breakers are 20a or lower. Half the set routes out a red wire, and the other half a black. 240v measured between them, and 120v measured between either black or red and ground. I'm assuming the back and red must be spliced somewhere down the line to route to both 240v outlets?

 

[kingchevy]

Maybe that 50 amp breaker is feeding a subpanel somewhere that you haven't found yet.

 

[wyliesdiesels]

Unfortunately i think theres no easy answer since the breaker has power at the lugs and the outlets are connected. Youre probably gonna have to strt by opening things up!

 

[brewchief]

Maybe that 50 amp breaker is feeding a subpanel somewhere that you haven't found yet.

This would make sense, dryer shouldn't be on a 50 amp anyway.

 

[justsam]

Fifty amp is pretty stout for dryer or compressor.
Are you sure this is not for hvac or range?
What gauge wire is connected?

 

[bjammmin]

Looked around for another subpanel, couldn't find any. Went back through the seller's inspection report as well as the one we had done and it looks like they are all accounted for. It's possible the older subpanel (outside) feeds the dryer receptacle, since that's right on the border between new and older sections of the house. But for some reason I doubt it. If that were true, the newer subpanel with the 50A two-pole breaker might only supply the 240v outlet in the garage. I don't know what the previous owner had connected at the garage receptacle - I suppose it could have been something that pulled more current than a compressor I suppose.

The wires seem like they could be 8AWG. The insulation is roughly 6mm diameter. The wires leaving the breaker and entering the garage receptacle look identical - as if they just ran straight there. May have to open up some walls as Wylie suggested!

The receptacle in the garage is a 10-50r, so it's technically rated for 50a I believe. At least that matches up with the 50a breaker.

Also might just try to get in touch with the previous owners via the realtors. Seems odd still to me that both receptacles would be dead given everything else is in great/clean/working shape. All these quick thoughts are much appreciated - thank you!

 

[wyliesdiesels]

Fifty amp is pretty stout for dryer or compressor.
Are you sure this is not for hvac or range?
What gauge wire is connected?

Not necesarily for a compressor. Some 5hp and 7.5hp compressors require that size breaker due to in-rush currents which can be 4x-6x FLC and breaker can be max of 250% of motor NEC table FLC...

 

[Ken Greene]

get a signal ringer and trace the wires back to the panel then you will nkow where theyactually are.

 

[TM98]

You only have the one 50 amp and everything else is 20 and lower?
Do you have a range that it could be feeding?

 

[Boredmechanic]

Did you have v on both legs to ground?

 

[Chuck122]

Did you have v on both legs to ground?

+1 on that
240v is usually two hot 120v offset by 180°
If they are wired wrong and they are not offset, you will have 120v to ground and 0v between the hot legs

 

[Milton Shaw]

Go with a signal tracer and use it to follow the wires in the wall. Northern tool has one that is not too expensive and works. Also some Fluke meters will detect 20/240 behind the walls with their volt detection function. On high setting it will follow from 8-12 inches from the wall. Just turn every thing else off in the box off except the 50 amp and trace it until it stops and there should be the break in the wire. Is it possible that wiring was moved in a remodel and a junction box is hidden somewhere you haven't seen.

 

[theoldwizard1]

get a signal ringer and trace the wires back to the panel then you will know where they actually are.

Go with a signal tracer and use it to follow the wires in the wall.

"Ringer", "wire tracer", "fox and hound" are all the same thing.

I would suggest that before you do this

1. Turn off the main breaker
2. Remove the 2 pole breaker from the load center
3. Disconnect the wires from that breaker
4. Turn the main breaker back on

Now you can use your ringer from either end !

There are a lot of wire tracers to choose from on eBay ($15-$75) but look in the "Electrical & Test Equipment" sub-category. Most will say for netwrk or telephone, but thee can be used on power lines (after the wire(s) is disconnected from the breaker). Some have adapters for 120v outlets, but all can be used on 240V outlet once you know how to use them.

I have a MS6812, but I have only used it on automotive wire harnesses.

 

[justsam]

Not necesarily for a compressor. Some 5hp and 7.5hp compressors require that size breaker due to in-rush currents which can be 4x-6x FLC and breaker can be max of 250% of motor NEC table FLC...

The10-50R is rated for a max. of 3HP I suspect due to the much higher in rush that it could see in motor applications.

Having said that it certainly is possible that someone did it regardless thinking they could plug in compressor, or welder, or?

 

[bjammmin]

At the two pole breaker the wires do read 240v across. Signal tracer sounds like a great idea! Perhaps it might also be worth me checking for continuity to make sure the wires out of the breaker are actually the same ones going to the receptacle.

I have a note out to the previous owners to try to get more info. But, I do have another theory. Inside the subpanel there are black/red ~8AWG wires that appear to run in from the wall and go straight to the neutral bus bar. I didn't think about this earlier, but there's also an older, empty hot tub on an upstairs deck. I'm wondering if the owner initially wired the garage 240v, but then later decided he (or his wife!) wanted a hot tub and cannibalized the 50a breaker for that and tied the garage 240v outlet to ground.

In any case, barring more info from the previous owners, it sounds like good ideas to start trying to trace the the wires/signals.

 

[justsam]

The hot tub scenario sounds plausible.
At my home some future HVAC wiring was used for a hot tub.
Can you measure voltage at hot tub location and see if it goes away when you throw the 50AMP breaker?

 

[theoldwizard1]

.Inside the subpanel there are black/red ~8AWG wires that appear to run in from the wall and go straight to the neutral bus bar.

That is a "for sure method" of killing a receptacle !

... and tied the garage 240v outlet to ground.

You know there is no voltage at those receptacles and you suspect that both grounds are tied to the neutral bar.

Quick test.

1. Turn off the main breaker.
2. At the receptacle is question, set your DMM to "Continuity" (or lowest ohms range) and insert the probes into the 2 hot slots. If you have continuity (or a very low ohm reading) you have confirmed those wires at the panel are the same ones at the receptacle.

I don't think that "sharing" the 240V line to the dryer receptacle with a different 240V receptacle, especially in another room, is "legal". If you have a gas dryer, remove the receptacle, splice wires if necessary and put a plate on the box.

 

[Mustang51js]

Follow the wire to see if there's a j-box somewhere with the wires disconnected

 

[fuzzytek]

My guess is the double 50 might be for central air conditioning. The other outlets my have been disconnected yo put the AC.

 

[bjammmin]

Got it working! I checked continuity in various routes as suggested (those out of the 50a breaker and those for some odd reason routed to ground) and figured out the wires on the breaker weren't even connected to the 240v receptacle in the garage. Turned off the main power and did some stripping and reconnecting and sure enough DMM read 240 at the garage plug. I doubt my compressor will need 50a, but it is a 5hp motor. I could probably change out the breaker for a 30a or 40a if I wanted to be safer. Thanks for the great ideas all! This is my first home and am already loving the DIY activities.

 

[Boredmechanic]

Good job sir!