gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
101128-2331 EST
Your troubleshooting procedure is inadequate.
Do any voltages change by more than a fraction of a volt at the main panel when you apply a load at the subpanel or the main panel?
If the main panel voltages are stable, then get a long extension cord or insulated wire. At the main panel connect this wire to the neutral. Be careful. Use electrically insulated gloves. Take the wire to the sub panel. This wire is a long test lead from the neutral at the main panel. Connect it to one side of the meter.
Use a high impedance digital voltmeter. Relative to the main panel neutral measure the voltage at the subpanel to ground, neutral, and each hot. Record these values.
Next put a 100 W lamp from neutral to one hot. Again measure the four voltages. Next from neutral to the other hot. Again record the values.
By now you should know what wires have high resistance connections.
Is the water pipe you are using for an EGC a conductive pipe all the way back to the main panel? If so and any hot wire appears to to be good, then connect a 100 W bulb from the good hot to the water pipe. Relative to your long test lead read the voltage to the water pipe at the subpanel, and to the hot supplying the lamp. What does this tell you? If the water pipe appears to be a good connection from the main to the sub, then try a 1500 W heater load. Again what are the results?
By now you should know where your problems with bad connections are. Get the setup to code as soon as possible. Maybe get a GFCI at the destination soon.
.
Your troubleshooting procedure is inadequate.
Do any voltages change by more than a fraction of a volt at the main panel when you apply a load at the subpanel or the main panel?
If the main panel voltages are stable, then get a long extension cord or insulated wire. At the main panel connect this wire to the neutral. Be careful. Use electrically insulated gloves. Take the wire to the sub panel. This wire is a long test lead from the neutral at the main panel. Connect it to one side of the meter.
Use a high impedance digital voltmeter. Relative to the main panel neutral measure the voltage at the subpanel to ground, neutral, and each hot. Record these values.
Next put a 100 W lamp from neutral to one hot. Again measure the four voltages. Next from neutral to the other hot. Again record the values.
By now you should know what wires have high resistance connections.
Is the water pipe you are using for an EGC a conductive pipe all the way back to the main panel? If so and any hot wire appears to to be good, then connect a 100 W bulb from the good hot to the water pipe. Relative to your long test lead read the voltage to the water pipe at the subpanel, and to the hot supplying the lamp. What does this tell you? If the water pipe appears to be a good connection from the main to the sub, then try a 1500 W heater load. Again what are the results?
By now you should know where your problems with bad connections are. Get the setup to code as soon as possible. Maybe get a GFCI at the destination soon.
.