240 volt 1 phase, voltage rises to 146v when they turn on the microwave or any other appliance.

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
Energy Electric said:
Well everyone guess what! we found another underground splice box and yes the neutral connection was corroded and melted thru the splice connector. How we found it was we had a spare conduit running from box to box and I was going to run a sperate wire thru it to check for the voltage from point A to point B and we could only get our fish tape in 100+ ft on each side and it was not moving so we stretched out the fish tap going both direction and guess what another splice box buried in the ground. Anyway I want to thank everyone for there input and trying to trouble shoot this .
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Great you found! Just out of curiosity what kind of connector was it?
 
T

TX+ MASTER#4544

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Location
Texas
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electrical Code instructor and mentor
Energy Electric said:
I have a client that has a 1 phase 240 volt service that has a 200amp main breaker at the meter panel and two underground pull boxes to his house to a 200amp main panel with a 200amp main breaker. he also has 3 tesla power wall back up units with batteries. As of yesterday all of a sudden his lights are flickering and his Microwave is running really slow. He had PG&E come out and check there side and they said that he has a bad neutral between the main breaker and his 200amp subpanel.
I respliced his neutral wire in one of his pull boxes and he still is having a issue with his microwave. So when i put my meter on his conductors it reads 122v on 1 phase and 130v on the second phase, when he turns on his drill press that 2 phase rises to 148volt ? I have tighten up every connection between his 200amp sub panel and his tesla power wall panel and still getting the same results. I have tighten up all of his grounds and neutral connections. Is there any one out there that can help me with this situation.
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Anybody check the receptacle(s) where the microwave and anything else on that circuit that has an unstable voltage?

Are those receptacle(s) fed with a multiwire branch circuit (2 phase wires,( black and red) and one neutral, white wire?

The white wire should be spliced and pig-tailed with only one white wire attached to one neutral screw terminal and not on separate terminals.

If the white wire (neutral) is not spliced and you have two white wires and one attached to each terminal it could cause a series circuit when they are separated. Resulting in higher voltages.

If you open the neutral conductor (separate the two white wires) it will cause unbalance voltages and thus be at a higher voltage.

NEC code requires that they be spliced and have one pig tail wire on the neutral receptacle terminal.

See 210.4, 240.15 (B)(1) and 300.13(B) Device Removal
Is there a 2 pole CB feeding those receptacle(s)?

Thanks for reading.
Comments accepted.
TX+MASTER #4544
 
ActionDave

ActionDave

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TX+ MASTER#4544 said:
Anybody check the receptacle(s) where the microwave and anything else on that circuit that has an unstable voltage?

Are those receptacle(s) fed with a multiwire branch circuit (2 phase wires,( black and red) and one neutral, white wire?

The white wire should be spliced and pig-tailed with only one white wire attached to one neutral screw terminal and not on separate terminals.

If the white wire (neutral) is not spliced and you have two white wires and one attached to each terminal it could cause a series circuit when they are separated. Resulting in higher voltages.

If you open the neutral conductor (separate the two white wires) it will cause unbalance voltages and thus be at a higher voltage.

NEC code requires that they be spliced and have one pig tail wire on the neutral receptacle terminal.

See 210.4, 240.15 (B)(1) and 300.13(B) Device Removal
Is there a 2 pole CB feeding those receptacle(s)?

Thanks for reading.
Comments accepted.
TX+MASTER #4544
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You end your post "Thanks for reading" which is ironic since it's obvious you didn't read any of the posts in the thread.
 
T

TX+ MASTER#4544

Member
Location
Texas
Occupation
electrical Code instructor and mentor
Energy Electric said:
Thank you , I have figured it out that neutral wire is damaged between the first and second splice box.
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EnergyElectric

You have a series circuit problem.

You said the voltage was 135v +108v = 243 volts. That's one of the rules of a series circuit....voltage is additive. 135 volts at one check point and 108 volts at another check point. I know 240 volts is a nominal (aprx.)voltage.

See my post from yesterday or day before about a multiwire branch circuit.

Serious tip for any one pulling multiwire branch circuit(s) use a 2 pole CB or handle ties so that you are on both phases and not just on one phase.

If you put your the red and black wire on the same phase it will cause an over load on the white (neutral) wire and that is a bad problem because it will not cancel out and cause an over load on the neutral, which most likely is a 20 amp circuit.

Also, see 210.4 and 240.15 (B) and especially 300.13 (B).

Thanks for reading.
Comments accepted.
TX+MASTER #4544
 
ActionDave

ActionDave

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Durango, CO, 10 h 20 min from the winged horses.
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