Questions about the 5500 2 Element 30a EStop PID

[therustytracks]

I had a friend look over the diagram for the 5500 2 element 30a EStop PID diagram.

He is telling me that the EStop switch will not cut the power and it will just blow the fuse. Can anyone explain why this would or wouldn't happen?

Other than that I have a pretty solid understanding of the diagram.

 

[orangehero]

I am assuming you're talking about PJ's diagram. The reasoning is that the control panel should always be used with an upstream GFCI. Using the E-Stop to short the circuit should trip the GFCI and cut power to the panel completely. The fuse is there just in case to protect the wiring. In this situation the issue is that GFCI is not designed to be used this way, and has a limited lifespan should you trip it often for some reason (maybe there are others, but you can read about the arguments elsewhere and make up your own mind).

Your other option is to have the E-Stop NC with a large contactor that switches power to the rest of the panel. In this situation the issue is that you would still have power in the panel up to the main contactor, so if you somehow got your entire panel soaking wet it could potentially still be dangerous. I do believe most industrial panels utilize such a design.

You should use an upstream GFCI in either design, though. In the latter case it should mitigate the danger of still having power in the panel.

 

[therustytracks]

I plan on using a gfci breaker in my main breaker box. What exactly would happen if I hit the estop button while plugged into the receptacle wired to this breaker?


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[orangehero]

Same thing as when you hit the "TEST" button on the gfci breaker.

 

[therustytracks]

That's what I figured. I couldn't figure out how he assumed the fuse would blow. I'm no electrician but I've done most of the updated electrical work in my house that was built in 1802. Which is pretty much everything. The knob and tube wiring was barely retired by the time I bought the house.


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