30 Amp receptacle on a 50 amp breaker?

[jetfixr]

I just finished up my Ebiab project. It is wired up with a 30 amp plug and I have replaced the 30 amp non-gfci breaker with a 30 amp gfci breaker so now I can plug it in to the dryer outlet in my laundry room. The problem is, the laundry room is quite cramped and since it is on wheels, I wouldn't mind being able to use it in the kitchen. I have a unused dedicated 50 amp circuit breaker for my cooktop (I use gas but the house was wired for electric as well). Would it break any codes to replace the 50 breaker with a 50 amp gfci and replace the receptacle with a 30 amp? My understanding is the breaker is mainly to protect the wiring, so the wiring should be ample to carry 30 amps and the 50 amp gfci should cover ground faults. If I use a 30 amp receptacle I could chose between brewing in the laundry room, or brewing in the kitchen. Also, I already own a 50 amp gfci breaker from an old hot tub I had.

 

[Joshuah57]

You are correct in saying that the breaker is to protect the wiring. You could even replace a 50 amp breaker with a 30 amp breaker. You cannot do the opposite though (replace a 30 amp with a 50 amp). The breaker is there to make sure the wire does not overheat and start a fire when it is overloaded.

 

[Bobby_M]

You can replace the breaker with a 30gfci. If you keep it 50 amp, you can still plug in a load of 24 amps and still be OK.

 

[InspectorJon]

Technically any wiring device, such as a receptacle, downstream from the circuit breaker should be rated the same or higher than the breaker. In this case it would be possible to draw more than the thirty amps the receptacle is rated for through it. If you did that it would over heat the receptacle. If you know the equipment you are using and will not be drawing more than 30 amps through the receptacle it will work but it will not be a code compliant installation. Codes are not written so much for situations where people know what they are doing but for what people might unknowingly do.

For example, you might leave this in this condition and move to a new house. The person moving in might have an electric range and find it easier to get a plug that fits the receptacle you left in the wall and put it on the end of the range cord rather than replace the receptacle with a proper one. That setup might start a fire. Lots if ifs and might be scenarios. Codes are an attempt to reduce the opportunity for unlikely things to happen. As said above the correct thing to do here would be to put a thirty amp circuit breaker upstream from the 30 amp receptacle. Conversely you could put a 50 amp cord end on your brewing equipment and use a 50 amp receptacle. Or you could use the 30 amp receptacle and 50 amp breaker, be careful and hope for the best . . .

 

[InspectorJon]

You are correct in saying that the breaker is to protect the wiring. You could even replace a 50 amp breaker with a 30 amp breaker. You cannot do the opposite though (replace a 30 amp with a 50 amp). The breaker is there to make sure the wire does not overheat and start a fire when it is overloaded.

The breaker is there to protect everything downstream that is part of the wiring system, that includes the receptacle as well as the wire. A thirty amp receptacle would overheat if 50 amps were drawn through it. Granted that is an unlikely scenario as no appliance that draws that much would have a 30 amp cord end on it but we never know what DIY type folks might wire up downstream from a 30 amp cord end.

 

[bruce_the_loon]

I'd be careful on two fronts. With the 50A breaker, you are protecting the wires from carrying above 50A.

Firstly, the existing wires from the breaker to the cooktop are rated for 50A, but can the 30A socket both take the heavier gauge wires in the terminals and take 50A on the terminals and pins? Same for the 30A plug.

Secondly, is the cable on your EBIAB controller rated for 50A or just 30A?

Your controller might never draw the full 30A the plugs are rated for under normal circumstances, but if something goes wrong and you suddenly draw 45A for example, the breaker won't trip, but the 30A plug and wires might burn.

I'd replace the 50A breaker with a 30A GFCI to make sure the entire circuit is protected at 30A, otherwise you have to look at some sort of 30A protection at the socket which might not even exist.

 

[Bobby_M]

Right, the absolute safest thing to do is to change the breaker AND receptacle to 30 amp which makes it safer for your controller and element cords to be 10 gauge.

 

[jetfixr]

Thanks guys, I had the 50 amp gfci so I was trying to shortcut. I will just get the correct 30 amp breaker and receptacle. Makes sense that even though the wiring is rated for 50 amps, the 30 amp receptacle is not up to the task, and if the equipent somehow pulled more then 30 amps the receptacle could fail.

 

[augiedoggy]

Another option would be to have breakers or fuses in your control panel and to not mess with the wall outlet (after adding the 50a gfci breaker) But rather have the circuits fused or protected from overdrawing in the panel. This would still be safer from what I understand, than having a regular 120v lamp or appliance that draws say 5 amps plugged into a 15a-20a wall outlet right? what is protecting the cord in those scenerios if someone puts a 300w bulb in the lamp or the appliance malfunctions and draws more than the power cord is rated for? My point is if you design the control panel correctly the risk is still the same as any other outlet in your house as I see it. Personally I chose to use breakers and fuses protecting each circuit inside my control panel which help troubleshoot further is something else fails and also allows me to continue finishing my brewday if one of the circuits where to fail.

Also 30a gfci breakers are not as common as the 50a type and usually cost more. For that reason I used a regular 30a breaker in my main panel and have a spa panel with the gfci wired up between my panel and the control panel for the gfci capabilities.