50 Amp Questions

I'm building a 2 PID, 50a control panel. I've purchased a kit from ebrewsupply and am also referencing some relevant information from Kal's site.

1. I've noticed that no one seems to have a 50a NEMA inlet. The ones linked to by Kal have only a non-NEMA configuration. What (if anything) needs to be done differently with these non-NEMA inlets to ensure proper safety?

2. Given #1, and given that the two connectors involved total to something like $200, what are the reasons why I wouldn't just wire the power cord directly into the control panel? I realize I'd need to immobilize the cable with respect to the enclosure and protect it from abrasion (and I'm not entirely sure how I'd do that yet), but are there other considerations?

3. The ebrewsupply suggestion for wiring the 50a parts of the circuit are to use 10 gauge wiring. This is consistent with what I've seen in other places for chassis wiring. Kal recommends 6 gauge wire. I'm curious what other people have decided here.

Thanks!

Just to be clear, are you talking about the power from the control panel to the element? Or breaker panel to the control panel?

Yes, you can hard-wire the control panel. The piece you should look for to anchor it is called a strain relief cord grip.

From a 50a circuit breaker you should run 6awg wire to the control panel. Wire is sized based upon the circuit protection (breaker or fuse), and smaller than 6awg the wire could catch fire before the breaker flips. If you are putting 25-30 amp breakers in the control panel, you can move down to 10awg wire after those breakers. Similarly, if you use other breakers/fuses downstream, wire from them can be downsized accordingly.

To be clear about the wiring, I'm not talking about the power cord to the control panel; I'm talking about purely inside-the-enclosure wiring; the short distance from power-in to ground and the buses.

EDIT: Actually, I guess it's really just from power-in to the power-in contactor. And if I hard-wire the power cord to that contactor, no other wire should be carrying more than 25a. The reason Kal's design has 6ga wires here is because all the power is going through the 50a shunt that's being used to measure current. As I don't have an ammeter, I don't have the same requirement.

In answer to your question #1, there is no NEMA standard for locking connectors above 30A which is why the California Standard (CS) has been adopted.

There are however NEMA standards for non-locking connectors e.g. NEMA 14-50 as commonly used for electric ovens and NEMA 6-50 which is often used for 220V welders.

Thanks; the strain relief cord grip looks perfect!