Beginner Wiring Question

[AndrewNSachs]

Hey guys,

I've been building (with much help and supervision) a toolbox-enclosed RIMS system for what feels like the better part of a lifetime. I've finally got everything running and fully operational except for the e-stop. I had it wired up like it is in P-J's diagrams (Hot to a 1 amp fuse, to two 1k ohm 1 watt resistors to the e-stop). When I hit the e-stop it cuts power to the whole system, but only because it trips my GFCI outlet that it is plugged in to. I've got the feeling that it shouldn't do that, but I could be wrong? Is it supposed to function this way? Or am I doing something wrong?

 

[The10mmKid]

That is exactly how P-J's circuit work.

'da Kid

 

[AndrewNSachs]

Well now I wish I didn't think it was malfunctioning and take it all apart...

Thanks!!

 

[The10mmKid]

Using P-J's design keeps you from installing expensive 'high ampacity' switches. It also gives you an opportunity to verify the GFCI will function properly when needed.

'da Kid

 

[BadNewsBrewery]

The resistors allow only a small trickle of electricity (for simplicities sake) to leak through to the GFCI, which in turn trips it. Arguably, this is the same method that the GFCI itself uses when you push the 'test' button, though I've never actually verified that. So all you're doing is remote tripping the GFCI, killing all power to your panel. It's the method I've used and I've been happy to have it. When you're on the other side of the room doing something and you hear the pump start to cavitate due to a stuck mash or whatever, it's much easier to run over and slam the e-stop than it is to push the right button or flip the right switch.
-Kevin

 

[Riot]

You can actually limit current a lot more than the two 1000 ohm resistors. I ran mine with about 12000 ohms of resistance and it still trips gfci just fine. I was concerned about what would happen if gfci failed and current stayed running through them, two 1 watt resistors really can't handle that much current for very long without becoming a fire hazard.

 

[BadNewsBrewery]

I was concerned about what would happen if gfci failed and current stayed running through them, two 1 watt resistors really can't handle that much current for very long without becoming a fire hazard.

That's why there's a 1A fuse, yeah?

 

[Riot]

Not really effective, at 120v current is limited to about 60mA with 2k ohms resistance. Even at that low of a current the resistors are dissapating 7+ watts. That is a fire hazard if gfci doesn't trip for whatever reason and the estop circuit stays energised. But the fuse won't blow either.