Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
The office at my job has a wall I installed an EMT run to single gang metal box. The office is old with some knob and tube and no ground.
I tied into a junction box in attic for feeding power to receptacle from black and white wire. However, the voltage was initially 116 volts a/c on small DVOM meter but would not power vacuum cleaner. The vacuum cleaner LEDS would light up but would dim and flicker no vacuum operation
I did clean up the connection of the wires at attic box as it had old exothermic welding left and carbon remains. Cut off wire and reconnected wire wire nuts and voltage increased to 125 volts to receptacle according to cheaper DVOM but still no operation of vacuum cleaner (which vacuum works on other receptacles)
I thought neutral and power may have been reversed at attic box since black and white were mixed on a wire nut but this did not help either when switched.
Plug in tester only says no ground. Voltmeter and oscilloscope have discrepancy voltages. 37 volts AC on oscilloscope and 116 volts AC showing on cheap DVOM.
I am aware that inductive loads such as laptops can cause waveform distortion but vacuum cleaner works on another circuit with similar distorted waveform and I did disconnect laptops and a/c system but waveforms did not change
I tied into a junction box in attic for feeding power to receptacle from black and white wire. However, the voltage was initially 116 volts a/c on small DVOM meter but would not power vacuum cleaner. The vacuum cleaner LEDS would light up but would dim and flicker no vacuum operation
I did clean up the connection of the wires at attic box as it had old exothermic welding left and carbon remains. Cut off wire and reconnected wire wire nuts and voltage increased to 125 volts to receptacle according to cheaper DVOM but still no operation of vacuum cleaner (which vacuum works on other receptacles)
I thought neutral and power may have been reversed at attic box since black and white were mixed on a wire nut but this did not help either when switched.
Plug in tester only says no ground. Voltmeter and oscilloscope have discrepancy voltages. 37 volts AC on oscilloscope and 116 volts AC showing on cheap DVOM.
I am aware that inductive loads such as laptops can cause waveform distortion but vacuum cleaner works on another circuit with similar distorted waveform and I did disconnect laptops and a/c system but waveforms did not change
