50A receptacle on a 30A Circuit

[Smart $]

Should it be an inadvertent overload or knowing overloading a circuit with the expectation that the OCPD will provide protection? I have always been of the school that one should never "intentionally" overload or short circuit a circuit.

Being of the electrical trade, most of us are taught that... but the general consumer is not. Even as electrical tradesman, we do not always know what is plugged into, and operating, on a multi-outlet circuit.

 

[kwired]

A 30at OCPD will certainly protect a 50a circuit down stream. The only caviot is when you have a 50a receptacle that provides the opportunity to plug in loads that have a 50a plug. This translates to the opportunity to overload the 30a circuit which would result in relying on the 30a OCPD to protect the 30a wire for which you never intentionally rely on an OCPD to protect a circuit from intentionally being overloaded. I would consider this issue as a coordination concern by providing an opportunity to overload the 30a circuit with a 50s receptacle and a 40a load.
In my own woodshop I do have oversized 30a twist locks on a 20a circuit but I am the sole user of the shop with machines that draw less current such.as 15a. Since twistlocks are not cheap and that's what I had and didn't find it logical to spend money of a lower rated twist lock..
I would not have the problem of someone plugging in a machine that would have a 25a load since I am the only user.

Someday you will not be here and right or wrong someone else will acquire your 30 amp twistlock on the 20 amp circuit.

That is how every general use branch circuit operates.

The expectation is that the OCPD will open when the circuit gets overloaded.

+1

Should it be an inadvertent overload or knowing overloading a circuit with the expectation that the OCPD will provide protection? I have always been of the school that one should never "intentionally" overload or short circuit a circuit.

How many average users know this? Only us electrical professionals and a limited number of others with some interest are paying attention to those details, everyone else expects if they can plug it in - that it should work for them, overcurrent protection still places limits on what they can run before they have issues.

 

[iwire]

Should it be an inadvertent overload or knowing overloading a circuit with the expectation that the OCPD will provide protection? I have always been of the school that one should never "intentionally" overload or short circuit a circuit.

I will never intentionally overload a circuit.

But the general public, not being aware of the circuit layout has no idea if they are plugging into a loaded circuit or an unloaded circuit.

The only protection is the assumption the OCPD will open.

Clearly the NEC assumes the OCPD will open in every instance the NEC allows multiple receptacles on one circuit.