help with dryer circuit please.

[Charlie Bob]

New customer called.She's saying the dryer is not working. there must be something wrong with plug.
I go thereand i found no voltage at plug.go check the breaker,is off,i turn it on.Go back to plug, now we have 245V L-L, 110V L1-N and 115V L2-N.
I tell the guy to check the Dryer, nothing.
I check for continuity, everything is OK. I pluged the cord, and check the connections at the dryer, 245V L1-L2, and 65V L1-n, 178V L2-N. Loose nuetral or broken neutral in cord. Idisconnect the neutral from the cord at dryer connection.I get 245, 110, and 117V at the cord, when i check at the dryer is showing open neutral though.

I tell the customer everything is normal up to the dryer.She needs to get somebody to work on the dryer and find an open neutral.
I charged him half a service call since they were first time customer.

He calls today telling me that a guy went over to work on it, and that light on the dryer came on the first time and then quit, breaker never tripped.
He took it apart and didn't find anything in it.They went and bought another dryer, and they tried it out at the store and worked.
They get home and didn't worked.
They now called me all worked out, they want me back and the guy even told me that it's got to work this time since they already paid me. Hell of a nerve.

What do you guys think could be the problem with this?

 

[LarryFine]

What do you guys think could be the problem with this?

It's still a neutral issue. You just haven't narrowed it down yet. You have to measure the voltages at every point from the panel to the terminals in the dryer wiring compartment while the imbalance is occurring.

Without the line-to-neutral load connected, the imbalanced voltages will not show up. (Even some POCO guys don't get that.) Check at the panel and at the receptacle. You can plug the dryer in with the cover off.

Hint: Only the heater element is wired line-to-line within the dryer; everything else is wired from line to neutral. The element won't come on unless the motors work, to prevent it from burning out.

 

[Charlie Bob]

It's still a neutral issue. You just haven't narrowed it down yet. You have to measure the voltages at every point from the panel to the terminals in the dryer wiring compartment while the imbalance is occurring.

Without the line-to-neutral load connected, the imbalanced voltages will not show up. (Even some POCO guys don't get that.) Check at the panel and at the receptacle. You can plug the dryer in with the cover off.

Hint: Only the heater element is wired line-to-line within the dryer; everything else is wired from line to neutral. The element won't come on unless the motors work, to prevent it from burning out.

Larry if there is an open neutral somewhere in the three wire circuit cable or at the panel, wouldn't the Voltage at the plug show that?

The inbalanced volatge occurred at the dryer connection. when i disconnected the cord i had normal voltage at the end of the cord.

 

[infinity]

New customer called.She's saying the dryer is not working. there must be something wrong with plug.
I go thereand i found no voltage at plug.go check the breaker,is off,i turn it on.Go back to plug, now we have 245V L-L, 110V L1-N and 115V L2-N.

Those measurement seem to be strange. Why is there a 20 volt difference between the L-L and L-N voltages?

 

[Charlie Bob]

Those measurement seem to be strange. Why is there a 20 volt difference between the L-L and L-N voltages?

I'm sorry, it should have read 120V and 125V.

 

[Volta]

Larry if there is an open neutral somewhere in the three wire circuit cable or at the panel, wouldn't the Voltage at the plug show that?

The inbalanced volatge occurred at the dryer connection. when i disconnected the cord i had normal voltage at the end of the cord.

As Larry mentioned, the line-neutral load must be connected to witness the voltage imbalance, so normal voltage with no load would make sense.

 

[NewOnMyOwn]

As Larry mentioned, the line-neutral load must be connected to witness the voltage imbalance, so normal voltage with no load would make sense.

How would he be getting any voltage to neutral at the receptacle if there was an open neutral?

 

[480sparky]

How would he be getting any voltage to neutral at the receptacle if there was an open neutral?

Maybe not completely open (0 ohms), but very high resistance.

 

[NewOnMyOwn]

Maybe not completely open (0 ohms), but very high resistance.

Gotcha. This thread is a good learning experience, I would have done the same thing as Charlie Bob.

 

[LarryFine]

Larry if there is an open neutral somewhere in the three wire circuit cable or at the panel, wouldn't the Voltage at the plug show that?

Only with a line-to-neutral load connected and on.

The inbalanced volatge occurred at the dryer connection. when i disconnected the cord i had normal voltage at the end of the cord.

That's because there was no load between the neutral and either line.

 

[LarryFine]

How would he be getting any voltage to neutral at the receptacle if there was an open neutral?

High-impedance voltmeter. Once again, a solenoid-type tester would expose it.

 

[NewOnMyOwn]

High-impedance voltmeter. Once again, a solenoid-type tester would expose it.

This would be in the case of a very loose neutral, a connection that is touching, but just barely?

 

[Charlie Bob]

Thank you Larry

 

[LarryFine]

This would be in the case of a very loose neutral, a connection that is touching, but just barely?

Two points:

1. "Just barely" can cover a range of resistance, and create a range of voltage readings, but a solenoid (or other low-impedance) tester will read more like what your meter reads with the load connected.

Again, if you test voltage at each point along the circuit (at the panel (check the neutral bus connection), at the receptacle, in the wiring compartment) when you read the imbalances.

The problem will be where the voltages change from correct to incorrect. You will also be able to measure voltage across points that should read zero, such as between a wire and its terminal.

2. A high-impedance voltmeter will likely read line voltage even with a completely open neutral, because of capacitance between the neutral conductor (on the load-side of the break) and the line conductors (and the earth somewhat.)

 

[LarryFine]

This would be in the case of a very loose neutral, a connection that is touching, but just barely?

To add, what I meant is that a low-impedance load (such as a solenoid tester, a 100w bulb, or a dryer's line-to-neutral loads) will expose the voltage differences, while a high-impedance meter won't.

The voltages must remain balanced (within a small range) under load for the load to function properly with line-to-neutral loads. Line-to-line-only loads have no 120v components.

Thank you Larry

Any ol' time.

 

[ceb58]

Make up a 3 wire drop cord, lug it into the orignal dryer breaker and plug the dryer in. If the dryer functions properly then something is wrong with the orignal circ. from the panel to the dryer plug. If it doesn't function properly then it should be something in the panel. Could be as simple as a bad breaker. Since you did not mention anything else going wrong other than the dryer chances are you can rule out a bad poco neutral.

 

[kwired]

I have a short test cord with alligator clips on one end and a 15 amp connector on the other. I would connect this to the circuit in question and plug in my electric heat gun to put a 1500 watt load on the circuit. If there is a connection issue somewhere on the circuit it will show itself fairly quick with that kind of a load on it.

 

[Teaspoon]

To add, what I meant is that a low-impedance load (such as a solenoid tester, a 100w bulb, or a dryer's line-to-neutral loads) will expose the voltage differences, while a high-impedance meter won't.

The voltages must remain balanced (within a small range) under load for the load to function properly with line-to-neutral loads. Line-to-line-only loads have no 120v components.


Any ol' time.

Yes this sounds very much like a service call i did a few years ago.
little differant situation same type of simptions. This customer had a 100 amp disconnect that fed his home shop. The disconnect was double lugged from the bottom of the meter base. volt meter would read proper voltage.
Light bulb tester would not light up . Problem loose neutral.
This was an old installation . After explaining to the customer about the dangers of his old outdated/overloaded service. he decided to have a new service upgrade/change-out.

 

[NewOnMyOwn]

2. A high-impedance voltmeter will likely read line voltage even with a completely open neutral, because of capacitance between the neutral conductor (on the load-side of the break) and the line conductors (and the earth somewhat.)

OK, so it doesn't even need to be a "just barely touching" neutral connection, it can be completely open and still read proper voltage?

I've never seen that before. I understand inductance screwing with a DMM or a tick tracer, but I didn't think a DMM would show full voltage L to N when the N is completely disconnected. Good to know, thanks!


ETA: Fluke makes a DMM with a "Lo Z" setting that is supposed to be as good as a solenoid tester. Do you believe that to be true, or should I just stick with my old Klein Wiggy?

http://support.fluke.com/find-sales/Download/Asset/2718074_6116_ENG_A_W.PDF

 

[kwired]

OK, so it doesn't even need to be a "just barely touching" neutral connection, it can be completely open and still read proper voltage?

I've never seen that before. I understand inductance screwing with a DMM or a tick tracer, but I didn't think a DMM would show full voltage L to N when the N is completely disconnected. Good to know, thanks!


ETA: Fluke makes a DMM with a "Lo Z" setting that is supposed to be as good as a solenoid tester. Do you believe that to be true, or should I just stick with my old Klein Wiggy?

http://support.fluke.com/find-sales/Download/Asset/2718074_6116_ENG_A_W.PDF

testing the circuit with load described in my prevoius post removes all doubt.