# 50 amp hot tub feeders



## myenergy

I usually install #6 feeders for a hot tub with a 50 amp rating but I cant figure out why. Can I use# 8 thhn . if not why. I have never clamped a hot tub drawing more than 30 A thats with all pumps and heaters on. referances please

Thanks


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## Electric Al

If it asks for 50 amp. Install 50 amp and # 6 feeders or your warranty will be void.


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## BuzzKill

myenergy said:


> I usually install #6 feeders for a hot tub with a 50 amp rating but I cant figure out why. Can I use# 8 thhn . if not why. I have never clamped a hot tub drawing more than 30 A thats with all pumps and heaters on. referances please
> 
> Thanks


you need to remember the spike in current when that motor starts to wind up.


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## 480sparky

Electric Al said:


> If it asks for 50 amp.........



50 amp _what_? Minimum branch circuit rating, or over-current protection, or both?

Look on the nameplate for MCA and OCD ratings.


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## TOOL_5150

Since we are on the subject - is it required to pull a full size ground for a 50A spa circuit, or can I run a #10 ground?

~Matt


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## BuzzKill

Heel I'd think a #12 might suffice but I'd go with #10


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## kwired

If you have 75 degree terminals and 75 degree conductor you can use #8 copper @ 50 amps. Remember that NM cable must be sized to 60 degree temperature rating so you can not use #8 if using NM cable. If equipment instructions state #6 minimum then you also cannot use #8.


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## Dennis Alwon

Many tub manufacturers spec that a full size egc must be used. I believe it is worded to say that the egc must be the same size as the ungrounded conductors.

I have given up using nm cable and now I run conduit so that the egc is not an issue.


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## Dennis Alwon

BuzzKill said:


> Heel I'd think a #12 might suffice but I'd go with #10


Buzz how could #12 suffice? Check Table 250.122 for EGC-- it is based on the breaker size.


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## BuzzKill

Dennis Alwon said:


> Buzz how could #12 suffice? Check Table 250.122 for EGC-- it is based on the breaker size.


I said "I think" it would suffice. What do I know? Enough to use #10, though. It's a pretty simple question with a pretty simple solution: check the code book. I'd be interested to see test results of how well certain size wires carry the fault current before disintegrating.


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## kwired

BuzzKill said:


> I said "I think" it would suffice. What do I know? Enough to use #10, though. It's a pretty simple question with a pretty simple solution: check the code book. I'd be interested to see test results of how well certain size wires carry the fault current before disintegrating.


sizing equipment ground conductors is not about sizing them to prevent the ground wire from overheating it about sizing it large enough to lower its impedance enough to operate the overcurrent device quickly.


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## Magnettica

TOOL_5150 said:


> Since we are on the subject - is it required to pull a full size ground for a 50A spa circuit, or can I run a #10 ground?
> 
> ~Matt



That would depend on both 110.3(B) and Table 250.122. :thumbsup:


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## idontknow

TOOL_5150 said:


> Since we are on the subject - is it required to pull a full size ground for a 50A spa circuit, or can I run a #10 ground?
> 
> ~Matt


Only if the power used for the spa is from a transformer or other seperately derived system.







I think.


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## TOOL_5150

Magnettica said:


> That would depend on both 110.3(B) and Table 250.122. :thumbsup:


Thanks, but I knew this part - it was post 8 from dennis I was unsure about. I am thinking it would be wise to just run a full size EGC to the spa disco. Unless I can check out the specific spa before I get the line ran.

~Matt


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## kwired

> Since we are on the subject - is it required to pull a full size ground for a 50A spa circuit, or can I run a #10 ground?


~Matt 



idontknow said:


> Only if the power used for the spa is from a transformer or other seperately derived system.
> 
> 
> 
> 
> 
> 
> I think.


I don't know of any requirement like this and I fail to see any logic as to why that would be a requirement. 

Voltage (assuming an unlimited capacity in the supply) and impedance of the circuit are the same no matter what the source is. So why should you need a different size conductor on one vs the other? 

If anything the SDS will likely have higher impedance and lower available current so you would want the larger conductor on it to allow more current to flow during a fault to allow faster operation of overcurrent device.


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## jwjrw

Some of the hot tubs I have done said to use #6 in the instructions.


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## kwired

jwjrw said:


> Some of the hot tubs I have done said to use #6 in the instructions.


then you must follow them instructions, if not in the instructions then follow NEC.


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## Dennis Alwon

idontknow said:


> Only if the power used for the spa is from a transformer or other seperately derived system.
> I think.


It would be good to back this up with an article number. Never heard of it before.


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## jwjrw

kwired said:


> then you must follow them instructions, if not in the instructions then follow NEC.


 
Thats why I said some say to use #6.


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## kwired

idontknow said:


> Only if the power used for the spa is from a transformer or other seperately derived system.
> 
> 
> 
> 
> 
> 
> 
> I think.





Dennis Alwon said:


> It would be good to back this up with an article number. Never heard of it before.


The only thing I find like this is 680.25 (B)(1) but it is in 680 part II for feeders for permanently installed pools and does not apply to hot tubs.

The only parts of 680 that apply to hot tubs and spas are Part I general and part IV spas and hot tubs


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## Dennis Alwon

Here are instructions from a PDF on Aruba Spas. I just did a google search and pick the first spa manuals I could find.



> *Important Safety Instructions
> SAVE THESE INSTRUCTIONS
> *​1. Read and follow all instructions .
> 2. A ground terminal is located on the power connection terminal block . To reduce the risk of electric shock this terminal must be connected to the grounding means provided in the electric supply service panel with a continuous copper wire equivalent in size to the circuit conductors supplying this equipment *or as required by local electrical codes.*
> All field installed metal components such as rails, ladders, drains or other similar hardware within 3 meters of the spa shall be bonded to the equipment grounding bus with copper conductors no smaller than #6 AWG wire.


This highlighted section gives us an out but the next paragraph throws a wrench in the works.


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## Dennis Alwon

kwired said:


> The only thing I find like this is 680.25 (B)(1) but it is in 680 part II for feeders for permanently installed pools and does not apply to hot tubs.
> 
> The only parts of 680 that apply to hot tubs and spas are Part I general and part IV spas and hot tubs



Well, y'all taught me something I did not know but that still does not require a full size ground. If you run a #6 ungrounded conductor then you can still use a #8 ground for a SDS according to this article. And, of course, it is for pools not tubs but still good to know. Thanks


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