I have a sauna that is about 100’ from power source, it is 25a 240v I’m using #10 THHN, my question is can I use a #12 ground?

[Rsemp]

I have a sauna that is about 100’ from power source, it is 25a 240v I’m using #10 THHN, my question is can I use a #12 ground?

 

[winnie]

I have a sauna that is about 100’ from power source, it is 25a 240v I’m using #10 THHN, my question is can I use a #12 ground?

Take a look at table 250.122 . If you have a 25A breaker, you must use a #10 ground. Other factors might require you to use an even larger ground, but you wouldn't be able to go smaller.


(from https://www.mikeholt.com/files/PDF/20_BG_250.122.pdf )

 

[Rsemp]

Disregard, I found my answer. Thanks

 

[infinity]

Disregard, I found my answer. Thanks

So what size did you come up with?

 

[don_resqcapt19]

If you are using 10AWG circuit conductors for a circuit with an OCPD of 30 amps or less, you must used a 10AWG EGC.

 

[Deltaforce]

Other factors might require you to use an even larger ground,

EGC size no require larger than circuit conductor size 250.122A

 

[don_resqcapt19]

EGC size no require larger than circuit conductor size 250.122A

Correct, but if you use a 1/0 circuit conductor for a 15 amp circuit, the EGC is required to be 1/0.

 

[winnie]

EGC size no require larger than circuit conductor size 250.122A

That is a good point. I was mentioning 250.122 as a minimum size and wanted to make it clear that there were other rules that could increase the size of the EGC. However there are a few corner cases where the allowed phase conductors may be smaller than table 250.122

 

[Deltaforce]

few corner cases where the allowed phase conductors may be smaller than table 250.122

Parallel conductors case?

 

[winnie]

I was thinking motor or HVAC loads where you might see a 30A breaker protecting 12 ga conductors

 

[Deltaforce]

I was thinking motor or HVAC loads where you might see a 30A breaker protecting 12 ga conductors

250.122A still apply. EGC size need no exceed 12awg

 

[infinity]

Parallel conductors case?

Sort of. The EGC may be required to be larger than the individual parallel phase conductors.

 

[winnie]

250.122A still apply. EGC size need no exceed 12awg

I'm not arguing with you. I pointed out the general table, you pointed out the exception to the table, I agreed with you. You asked if I was thinking about large parallel installations, I said I was thinking about motor and HVAC installations.

 

[infinity]

Also the EGC for tap conductors is based on the OCPD ahead of the tap so that EGC may be required to be larger than the tap conductors.

 

[Dennis Alwon]

Also the EGC for tap conductors is based on the OCPD ahead of the tap so that EGC may be required to be larger than the tap conductors.

I didn't know that. I assumed the smaller taps were enough to trip the breaker then the smaller equipment grounding conductor would also work.

 

[Deltaforce]

I'm not arguing with you. I pointed out the general table, you pointed out the exception to the table, I agreed with you. You asked if I was thinking about large parallel installations, I said I was thinking about motor and HVAC installations.

Agreement by experts like you joyful moments

 

[wwhitney]

Also the EGC for tap conductors is based on the OCPD ahead of the tap so that EGC may be required to be larger than the tap conductors.

But the first sentence of 250.122(A) would still mean that sizing the EGC equal to the tap conductors would suffice?

Cheers, Wayne

 

[infinity]

But the first sentence of 250.122(A) would still mean that sizing the EGC equal to the tap conductors would suffice?

Cheers, Wayne

Yes. I should have stated that the EGC is based on the OCPD ahead of the tap which may result in it being larger than the EGC from T250.122. For the reason Dennis mentioned it wouldn't need to be larger than the tap conductors.