Extension Cords: gauge, length, & amps

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BreakingBarley

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Whilst shopping around for a short extension chord to feed my EBIAB control panel, I became confused by the amperage ratings on the chords.

My control panel needs 2 separate 120v/20a circuits to feed 2 elements (2250w & 1650w), a pump, and various LEDs, contactors, & relays. The 2250w element is on its own “circuit” in the panel (18+ amps) and is powered by a 20a outlet nearby, but the other inlet will need an extension to reach a different circuit in the house near my brewing space (rental home). The second internal “circuit” powering the 1650w element and accessories will run less amps than the other, but will be near or over 15 amps.

Many of the 10 gauge chords I’ve found are only rated for 15 amps per their packaging, even for shorter 25’ chords. Shouldn’t a 10 gauge chord be able to carry 20+ amps? Some sources show a 10 awg extension chord can carry 16-20 amps for shorter lengths (<100’). Is the 15 amp rating limited by the plug and socket’s max amperage, or are the manufacturers being conservative in their max rating? What gives and does anyone else reliably use prebuilt extension chords to power your brewing system?

 

Bobby_M

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The tables below are pretty accurate. Whether you need to go 25ft or 50ft, I would still get a cord that is 12 gauge. If that cable has a NEMA 5-15 on both ends, they would likely only rate it for 15 amps because that's the NEMA standard plug configuration. The cable and connectors are physically capable of carrying 20 amps, but since the plug can be plugged in to a 15 amp receptacle, they don't want you to actually RUN 20 amps on it. The breaker in the main panel will trip after a few minutes in that case.

If you're plugging into a 20 amp receptacle, which would have a NEMA 5-20 blade configuration, it would be best to use a 12 gauge cord that actually has the matching NEMA 5-20P and 5-20R configuration on it.




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BreakingBarley

BreakingBarley

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The cable and connectors are physically capable of carrying 20 amps, but since the plug can be plugged in to a 15 amp receptacle, they don't want you to actually RUN 20 amps on it. The breaker in the main panel will trip after a few minutes in that case.

Thanks for the reply- I think I glazed over this while planning the panel. All of the breakers in the house are 20 amp, but none of the outlets are 20 amp receptacles (sideways prong) :eek:

I’ll have to talk to the owner to install some 20 amp receptacles (as long as wire in the wall is 12 awg or larger), or conversely, use a lower wattage element to stay under 15 amps (not ideal).


 

Bobby_M

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NEC allows for 15 amp receptacles to be put on 20 amp branch circuits due to the expectation that a wide mix of lower amp appliances will be distributed across several receptacles. Most 15 amp receptacles are physically capable of carrying 20 amps as long as the wires are not pushed into the back "stab holes" and the conductors are in fact 12 gauge. The only reason it wouldn't be 12 gauge is if the breakers were originally all 15 amp and they got bulk changed out illegally.
 

toadie

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I'm guessing you are not in the US or Can, but my vote is to get a new box/outlet installed where you need it. Obviously provided the panel can handle it. I think this makes sense even when renting tho obviously not if you plan on moving soonish. Cheers.
 
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BreakingBarley

BreakingBarley

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NEC allows for 15 amp receptacles to be put on 20 amp branch circuits due to the expectation that a wide mix of lower amp appliances will be distributed across several receptacles. Most 15 amp receptacles are physically capable of carrying 20 amps as long as the wires are not pushed into the back "stab holes" and the conductors are in fact 12 gauge. The only reason it wouldn't be 12 gauge is if the breakers were originally all 15 amp and they got bulk changed out illegally.

Yup, well said- thanks for the help and your support to the homebrew community!


I'm guessing you are not in the US or Can, but my vote is to get a new box/outlet installed where you need it. Obviously provided the panel can handle it. I think this makes sense even when renting tho obviously not if you plan on moving soonish. Cheers.

Close, living in Texas currently 😂😂

I agree, sizing & installing an appropriate socket is the safest bet to not burn something up, cheers!
 
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