dennisonwilliams
New member
- Location
- Oakland, CA, USA
I have a branch circuit that has around 80Volts on it. Can anyone give some ideas of the cause?
Branch circuit low voltage causes
- Thread starter dennisonwilliams
- Start date
- Status
Bladnaster
Member
- Location
- CT.
Recently had this issue on one of the legs on a two pole breaker. There were other issues as well which I had to repair, but once I did, and got everything back together, flipped the breaker and still was getting a low reading. Ended up being something with the breaker itself. Tested the breaker, then swapped it with another (in the panel) real quick just to make sure. Put in a new one and all was well.
Just a possibility.
Just a possibility.
readydave8
re member
- Location
- Clarkesville, Georgia
- Occupation
- electrician
Yes.
Also: If one leg is dead for whatever reason, may be voltage from a water heater or other load connected to both legs.
Of course there would be other symptons as well, for example water heater not heating.
jim123
Member
- Location
- new castle,de
could be induced voltage
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
141914-2137 EDT
Troubleshooting involves logical analysis, measurements at various points, knowledge of the characteristics and capabilities of your instruments, electrical circuit theory, and deduction.
I prefer the use of a high input impedance digital voltmeter, and when needed a 10 ohm or so test load at 120 V. A long extension cord to provide a long test lead when needed. For most routine work I don't care whether the meter is RMS or average reading.
In your case I would go to the main panel and measure the voltage from the EGC to the neutral bus and from the EGC to the bus for the phase with the problem. Do this no load and with the 10 ohms on the bus of concern. Shouldn't be much change from no load to the 10 ohm load. My reading is 1 millivolt with nominal house load between EGC anfd neutral..
Next measure the output voltage of the breaker for the problem circuit relative to EGC. With and without the 10 ohm load on the circuit. I have a change of about 0.8 V on a QO-20 breaker with 13 A.
Then test various outlets on the problem circuit.
.
Troubleshooting involves logical analysis, measurements at various points, knowledge of the characteristics and capabilities of your instruments, electrical circuit theory, and deduction.
I prefer the use of a high input impedance digital voltmeter, and when needed a 10 ohm or so test load at 120 V. A long extension cord to provide a long test lead when needed. For most routine work I don't care whether the meter is RMS or average reading.
In your case I would go to the main panel and measure the voltage from the EGC to the neutral bus and from the EGC to the bus for the phase with the problem. Do this no load and with the 10 ohms on the bus of concern. Shouldn't be much change from no load to the 10 ohm load. My reading is 1 millivolt with nominal house load between EGC anfd neutral..
Next measure the output voltage of the breaker for the problem circuit relative to EGC. With and without the 10 ohm load on the circuit. I have a change of about 0.8 V on a QO-20 breaker with 13 A.
Then test various outlets on the problem circuit.
.
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