Voltage Drop on Circuit to Garage

[Shaker06]

There are two 20 Amp circuits running from my home to my detached garage. Circuit #1 operates fine and maintains a consistent voltage read around 118 Volts, even under a sizable load. Circuit #2 reads in at 117 Volts in the garage but drops substantially whenever I put anything, even a 100 Watt bulb across it (Down to around 94 Volts). In fact, circuit #2 eventually fades complete out until I reset the breaker and remove all loads. All wiring inside the garage has been checked and everything is running in parallel. I suspect the problem is either at the breaker or in the underground wiring itself.

How do I locate the root of the problem? And if the problem is found to be in the underground positive wire on circuit #2, can I run the return to the house using circuit #1’s neutral? Or, should I start digging for new line?

Note: The house is approximately 25 ft from the garage with #12 wiring that is at least 40 years old.

[kactuskid]

It sounds like there's a loose connection on the circuit. I would check all connections everywhere. If the wires are stuck in the little holes in the backs of the receptacles, remove them and wrap them around the screws on the sides. These backstabbed holes are the cause of lots of loose connections. Check junction boxs, under wire nuts and the connections at the breaker also.


PS: It is against code to have more than one circuit installed between your home and your detached garage. If more than a single 20 amp circuit is needed then a subpanel must be installed in the garage.

And no, you cannot use the neutral of another circuit, that is extremely dangerous. Like said, one circuit max to a garage unless a subpanel is installed.

[Shaker06]

Thanks for the reply. I will check the connection at the breaker.