Shopsmith Forums

I had a visit from my brother-in-law over the holidays and I allowed him to plug his motorhome into what I thought was a dedicated 20A circuit. I have been using this circuit for years with my two Shopsmiths and the moment he plugged in, tripped a 15A GFCI a little farther down the wall. Bewildered, I pulled the siding off the wall (I planned to replace it anyway) and discovered my 20a outlet was indeed fed from the 15A GFCI (with 14ga. cable). I rewired the GFCI with 12g cable, replaced the 15A with a 20A GFCI and ran new 20A cable to the outlet. Thank God the breaker box was only a foot away the GFCI. I plugged the Shopsmith into the outlet and when I powered it on, it immediately tripped the GFCI. I reset the GFCI and plugged the Shopsmith into the GFCI and at power on, it tripped again. Thinking I had a possible wiring problem, I used my handy dandy plug-in tester and all the wiring checked good. I disconnected the wiring at the GFCI for the outlet, plugged the Shopsmith into the GFCI and when I turned it on, it purred like a kitten. How can a single outlet downstream cause enough of an issue to trip a GFCI?

How did you connect the 'outlet' wiring to the GFCI? 5 terminals including the ground.

Yes, the two from the breaker went to the line in and the two to the outlet went to the load. The two grounds were tied together and connected to the ground screw.

You can peruse the thread linked below if you want but I highly recommend installing a hospital grade 20A GFCI circuit to try first. In my experience there is a huge variation in quality of GFCI receptacles sold in the big box stores. The cheaper ones are garbage (IMHO) and are more prone to nuisance tripping whereas the hospital grade ones are less likely to nuisance trip.

https://forum.shopsmith.com/viewtopic. ... hilit=GFci

I see they have a Leviton Hospital grade 20A for $22.53 on Amazon. I will probably try that. Still makes no sense that the second outlet causes some type of interference that cause it to trip. The GFCI is working fine with nothing else associated with it, no nuisance trips at all.

WileyCoyote wrote: ↑Sun Jun 13, 2021 7:27 pm Still makes no sense that the second outlet causes some type of interference that cause it to trip.

The second outlet is connected to the load side of the GFCI right? If so, any current imbalance between hot and neutral on that 2nd outlet will trip the GFCI.

Yes, it was on the load side but with nothing plugged into the outlet. Until I get the new GFCI in I will continue to use the GFCI as a dedicated outlet for the Shopsmith. My second Shopsmith would normally be plugged into the outlet on the load side.

WileyCoyote wrote: ↑Sun Jun 13, 2021 10:09 pm Yes, it was on the load side but with nothing plugged into the outlet. Until I get the new GFCI in I will continue to use the GFCI as a dedicated outlet for the Shopsmith. My second Shopsmith would normally be plugged into the outlet on the load side.

Sorry. I didn’t understand that point when I responded before. There could possibly be a shared neutral between two branch circuits causing the GFCI to trip. If that 2nd outlet is old and worn it could possibly be to blame but seems like a long shot to me. Same goes for the wiring. Basically any leakage path that causes an imbalance between hot and neutral will trip the GFCI. However I would still start with putting a brand new hospital grade GFCI in first to see if it fixes it. It has fixed nuisance tripping more than once for me.

Finding reasons for GFCI receptacles tripping isn't always easy. I have great luck with them working without tripping. I have around 25 of them in use in my house and garage and none of them give me any issues with tripping. Mine are all the basic low priced hardware store GFCIs and none of them give me any problems.
I get the standard quality ones for $7-8 each compared to hospital grade ones for a bit over $30. Since I've not had any problems with the low priced ones, they are still my first pick.

garys wrote: ↑Mon Jun 14, 2021 7:47 am Finding reasons for GFCI receptacles tripping isn't always easy. I have great luck with them working without tripping. I have around 25 of them in use in my house and garage and none of them give me any issues with tripping. Mine are all the basic low priced hardware store GFCIs and none of them give me any problems.
I get the standard quality ones for $7-8 each compared to hospital grade ones for a bit over $30. Since I've not had any problems with the low priced ones, they are still my first pick.

25 of them in use seems like a big number, I think I have four or five. I'm guessing yours are not generally wired to provide downstream protection and I kind of like that approach, especially for the garage/shop. I have a refrigerator and freezer in my garage, so nuisance trips can be even more of a nuisance. Most installations I've seen one GFCI outlet or breaker provides protection for several downstream outlets, making it much harder to determine the source of a trip. Is yours wired the way I'm thinking? I'd guess you always use the 'line' terminals and never use the 'load' terminals on the GFCI outlets.(?)

- David