Troubleshooting a dryer outlet

[zappy]

I was testing the outlet with my wiggy, H-H 240, BLK to Grd 120, RED to Grd a pulsating 120v. My wiggy would go on and off. Then I went Cold water pipe to Grd on outlet, a pulsating but not as strong. Anyone have any suggestions about what this could be? Thank you for your help.

P.S. Also checked cold water pipe with a ticker and that didn't sense any voltage on the pipe, but it did sense voltage on the Grd on the outlet.

 

[kwired]

I was testing the outlet with my wiggy, H-H 240, BLK to Grd 120, RED to Grd a pulsating 120v. My wiggy would go on and off. Then I went Cold water pipe to Grd on outlet, a pulsating but not as strong. Anyone have any suggestions about what this could be? Thank you for your help.

P.S. Also checked cold water pipe with a ticker and that didn't sense any voltage on the pipe, but it did sense voltage on the Grd on the outlet.

Some load with pulsating current connected somewhere on the system, and is drawing voltage down enough with each pulse to detect with your wiggy?

 

[ActionDave]

Three wire dryer outlet or four?

 

[zappy]

Three wire dryer outlet or four?

Three wire.

 

[ActionDave]

My opinion- you can keep looking for the problem or you can cut to the chase and pull a new circuit to the dryer.

 

[kwired]

My opinion- you can keep looking for the problem or you can cut to the chase and pull a new circuit to the dryer.

I would make sure that the pulsating voltage doesn't exist at the panel first.

Next thing we need to know is if this pulsating was measured with or without load on the dryer circuit, and are we talking about full voltage pulsing, 50%, 25%, 10% of full voltage pulsing...

 

[Dennis Alwon]

You sure it is not the meter?

 

[1793]

You sure it is not the meter?

I have that thought as well. A Wiggy is my first choice of tester, however when I get into a situation like this I will break out my Digital meter so I can see exactly what the reading(s) are and it verifies that my tester(s) are working correctly.

 

[Rewire]

Other information is needed such as age of house ,type of wiring,location of dryer,why were you called out?

 

[zappy]

I would make sure that the pulsating voltage doesn't exist at the panel first.

Next thing we need to know is if this pulsating was measured with or without load on the dryer circuit, and are we talking about full voltage pulsing, 50%, 25%, 10% of full voltage pulsing...

Well just my wiggy as far as loading the circuit. As far as percentage not sure exactly.

 

[Stevareno]

Check the panel. I would think that if there is a pulse at the outlet, you would be able to see it in the panel as well.

I would start with everything turned on at the panel. Put the meter at the outlet where you can witness the pulsing.

Start turning off breakers one by one, checking the meter after each one until you find the other circuit causing the pulse, or you are left with nothing but the dryer breaker on.

 

[kwired]

Well just my wiggy as far as loading the circuit. As far as percentage not sure exactly.

I guess my first reply was in response to the suggestion to just pulling a new circuit to the dryer.

What I was after is - does the same problem exist if you check voltage at the panel? If so the problem is not in the dryer circuit itself but is upstream somewhere and pulling a new circuit will fix nothing.

If the problem is at the dryer outlet only and you have no load on it, well we would have something very unusual and need to investigate pretty thoroughly. Voltage will not change with no change in load in a situation like that (and remain stable at the panel)

 

[TobyD]

This may have been previously suggested.I haven't read all the comments.But, have you actually checked the conductors directly?Are you probing into the outlet itself,check directly onto the conductors...

 

[zappy]

Found problem

Found problem

Neutral bar in sub panel was floating. Once I got that grounded everything was fine. I think since it had no where to go to ground at the neutral bar, it went back through the other neutrals connected to in, and found ground through a appliance? That's why it pulsed and why the stereo in the garage went on and off when I stuck my wiggy in the dryer outlet Hot to ground?

 

[kwired]

Neutral bar in sub panel was floating. Once I got that grounded everything was fine. I think since it had no where to go to ground at the neutral bar, it went back through the other neutrals connected to in, and found ground through a appliance? That's why it pulsed and why the stereo in the garage went on and off when I stuck my wiggy in the dryer outlet Hot to ground?

It back through other neutrals and through other loads until finding the opposing 120 volt line. If neutral were grounded someplace you would have steady voltage, one or more of the associated loads is where pulsing was coming from and you were connected in series with that load.

 

[ActionDave]

Neutral bar in sub panel was floating. Once I got that grounded everything was fine. I think since it had no where to go to ground at the neutral bar, it went back through the other neutrals connected to in, and found ground through a appliance? That's why it pulsed and why the stereo in the garage went on and off when I stuck my wiggy in the dryer outlet Hot to ground?

Nevermind. Need to get back to work

 

[1793]

Neutral bar in sub panel was floating. Once I got that grounded everything was fine. I think since it had no where to go to ground at the neutral bar, it went back through the other neutrals connected to in, and found ground through a appliance? That's why it pulsed and why the stereo in the garage went on and off when I stuck my wiggy in the dryer outlet Hot to ground?

I thought sub-panels neutrals were supposed to be "floating", so how did you ground it?

 

[Strathead]

I have that thought as well. A Wiggy is my first choice of tester, however when I get into a situation like this I will break out my Digital meter so I can see exactly what the reading(s) are and it verifies that my tester(s) are working correctly.

In this case it seems a good old reliable Simpson 260 or 269 would be the better choice.

 

[kwired]

I thought sub-panels neutrals were supposed to be "floating", so how did you ground it?

That does warrant some clarification, the neutral in the sub panel should not be bonded to the EGC, if that is all you did to "fix" the problem, you created a condition where the EGC and any other connected metal paths are now carrying neutral current. The real problem was an open neutral someplace in the supply.