What would cause lights to shut off when pressing a dryer start button AND MORE!!?

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I love these types of problems.....I'd like to know what voltage you have from neutral to ground at the light switch with lights on , it will be less than 120. then again neutral to ground when dryer is started.
 
Does the dryer actually start?
Depending on whether the lights are all on the same L bus, you could get either brightening or dimming when load was added to the same or the opposite line.
 
kwired said:
Could be bad neutral, could be bad ungrounded conductor.

Do you read ~240 volts from ungrounded to ungrounded?

Are there any 240 volt appliances, if so do they work?

Does the dryer start, or attempt to do anything when you press the start button or does lights you mentioned just go out and nothing from the dryer?

Troubleshooting hint involving the dryer: most electric dryers have 240 volt heat elements but the motor and controls are 120 volts. The heater is interlocked with a centrifugal switch on the motor and it will not heat unless the motor is up to speed and the centrigugal switch is closed, so pressing start button is not closing a 240 volt circuit it is closing the 120 volt motor circuit, the 240 volt heater can only be placed on the system after the motor does start.
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I did get 220V voltage phase to phase.
The 240V appliances do not work.
 
cowboyjwc said:
See my answer. That will affect the whole house. Check ground to each phase and phase to phase. With a bad neutral the lights will usually get brighter when a load is added.
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The lights get dimmer or go off all together. I shut off ALL of the circuits except for the kitchen lighting circuit. And with one switch on it appeared to be ok, but as soon as you turn on other lights they dimmed or shut off.
 
sparky_chick said:
I did get 220V voltage phase to phase.
The 240V appliances do not work.
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What does that ungrounded to ungrounded do when a 240 volt load is applied? What does it do if you shut the main off?

Don't use the dryer for this 240 volt load test, as I mentioned before it doesn't close circuit to 240 volt heater until after the motor is running, no motor run, no 240 volt load applied. If they don't have a water heater, 240 volt heater, or range with non electronic controls you may need to improvise and bring in something to test with, worst case rig up two 120 volt resistive loads (preferably identical loads so they self balance) and connect them in series. Couple incandescent lamps would work.

Kind of sounding more like a lost ungrounded conductor then a lost neutral - especially if no lights ever get brighter when there are load changes.
 
I usually test neutral to ground for continuity when something doesnt work so that I have a reference thst im sure of the always phase to neutral phase to ground phase to phase. What were the actual numbers on the volt meter. I have seen lights backfed from a neutral and they work if the load isnt too taxing. . If they remove the bulbs down to one it might stay on.
 
electricalist said:
Mr. KWIRED. How obsurd would it be if a hot and neutral were reversed somewhere? These lights are a backfed neutral?
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If on a branch circuit, wouldn't cause the kind of trouble the OP is having, you may get lights that don't shut off if there is a ground fault on a switch loop with reversed hot/neutral. If on the service or a feeder, problems would have been obvious right away - this is apparently something that had been working correctly before something failed.

What does happen when you lose an ungrounded conductor on the service or a feeder is you do get backfeed through 240 volt loads and this does make the "dead" side function to some degree. Example of what could be happening to OP is backfeed is through the water heater making 120 volt items work on the "dead" side. When he tries to start dryer, he puts low enough impedance load in the dead side it drops the voltage enough to make lights go out that are also connected to dead side. All one needs to do to kill everything on dead side is open the water heater breaker (and any other 240 breakers that have a connected load) and then you open the "backfeed" and the dead side will actually be dead. Seen and fixed many underground lost service/feeders that presented same problem when an ungrounded conductor goes bad. Same thing happens if you have fuses for main overcurrent protection and one of them is blown.
 
After reading that the dryer does NOT turn on, and neither does any other 240v in the house, I'm curious where the voltage readings were taken

Did you check the voltage before the main, or after the main (such as individual breakers, or the bus bars)?


I'm beginning to think it's just a bad main breaker, not feeding through one leg
 
James L said:
After reading that the dryer does NOT turn on, and neither does any other 240v in the house, I'm curious where the voltage readings were taken

Did you check the voltage before the main, or after the main (such as individual breakers, or the bus bars)?


I'm beginning to think it's just a bad main breaker, not feeding through one leg
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The fact he said he did measure 220 volts makes this a good possibility, we don't know where that was measured, but if an incoming ungrounded conductor is lost he should never have gotten more then ~120 unless measurement was ahead of the problem.
 
kwired said:
The fact he said he did measure 220 volts makes this a good possibility, we don't know where that was measured, but if an incoming ungrounded conductor is lost he should never have gotten more then ~120 unless measurement was ahead of the problem.
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You get the 220 across the lines but you will only get 120 on one of the phases and 0 on the other.
 
cowboyjwc said:
You get the 220 across the lines but you will only get 120 on one of the phases and 0 on the other.
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If you lose an ungrounded conductor of a 120/240 single phase system you never get any reading over 120 at any point of measurement. If OP had 220 at line side of main breaker then he never lost an ungrounded conductor up to that point, but could have lost it through the breaker - needs to check load side as well.
 
GoldDigger said:
Even with vectors you cannot get 120 + 0 = 220. :)
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then you get 110 and 110 but not 220, I can never remember which it is. Yes Kwired on the load side but it could also be at the meter if the utility dropped a phase.

It could be at the line coming in, a bad meter, a burned meter socket, a bad main breaker, a burned bus, or a bad circuit breaker.

You check the circuit breaker first and if it shows up there then you go to the main and if it shows up there then you pull the meter and check across the line side if it shows up there it's a utility issue, if it doesn't then it's probably the main breaker. I've found this three or four different times.

It's very easy to figure it out. If the refer or any other 110 motor loads sounds like they are working hard at start up, that's what it is.
 
cowboyjwc said:
then you get 110 and 110 but not 220, I can never remember which it is. Yes Kwired on the load side but it could also be at the meter if the utility dropped a phase.

It could be at the line coming in, a bad meter, a burned meter socket, a bad main breaker, a burned bus, or a bad circuit breaker.

You check the circuit breaker first and if it shows up there then you go to the main and if it shows up there then you pull the meter and check across the line side if it shows up there it's a utility issue, if it doesn't then it's probably the main breaker. I've found this three or four different times.

It's very easy to figure it out. If the refer or any other 110 motor loads sounds like they are working hard at start up, that's what it is.
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The 120 volt loads on the "good" side will not have any problems, they will see same voltage they normally see, it is the "dead" side that is backfeeding through a 240 volt load that will see problems. If light loads are all that is present one may not notice any problem, but the more load is added the more the 240 volt load that is in series with it will drop the voltage. Now place a somewhat heavier load suddenly in the circuit and it will drop voltage to a very low level.

I've fixed more problems of this nature involving underground faults then because of a failed pole on a breaker. Next on the list is probably blown main fuse - the symptoms are same because the problem is still a loss of continuity of an ungrounded conductor
to the source.
 
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