I’m replacing a motor on my small, approx. 10 gal., compressor w/110v motor. The on/off pressure switch is wired though the motor by the neutral. I was always taught to NEVER wire house switching through/by the neutral. Is this Okay to switch the neutral. Don’t have the NEC handy. Thanks for the help.

 

Switching a neutral is incredibly dangerous.

I'd wire it correctly regardless of how it was shipped from the factory (which is probably wrong).

NEC doesn't concern itself with the wiring of a device like this. UL (for US) (or the Canadian equivalent) would be the agency that would have any oversight.

Steve

 

That's mostly so that someone doesn't go and turn off a light switch to change a fixture, then grabs the still live wire.
Ideally, it should switch both.

 

Worked on a water heater in mexico yeasrs ago and first thing I did was open the circuit breaker. Then went to work disconnecting the wiring and just for grins I thought I would test it with my meter. Glad I did because as it turns out the breaker was switching the neutral. That could have been my last job!

 

The garage at the house I live in now had the lights wired up so that they were switching the neutral. I have since fixed it but I can't help but shake my head at the hacks that do that kind of crap.

 

Wired the new motor and switched the hot. Everything working fine. Thanks for the help.

 

well if I read you right, the compressor mounted shutoff switch was wired this way, the swtich that shuts off the motor at a certain pressure and unloads the output line, and then turns it back on on a pressure drop?

the reason being, if the compressor is grounded (as it should be) or the piping (if installed) then if there is a switch fault or moisture/shavings in the line, you dont get an internal short (plus if the compressor is truly 110v and is plugged in behind a 20-pass20 GFI, it will trip on moderately humid days)

 

Now I'm confused. Let me clarify the ORIGINAL compressor wiring. The 110v line voltage connected inside the motor was black (+/hot) direct connect and white (-/neutral) switched thru the On/off pressure switch. With the NEW motor it is switched thru the black(+/hot). It is indeed plugged into a 20 amp GFCI, however, either way it was wired, it never popped the GFCI. The plug wiring is grounded to the motor frame also.