Main power wire gauge for 50A panel

I've searched the forum and can't see to find a consistent answer for this. What size wire should I use to go from a 50A breaker in my main panel to a 50A spa panel with GFCI to my control panel? I feel like I've seen both 6 and 8 gauge copper THHN recommended. Also, is conduit needed or can the wire just be run through the wall?

I know there are a lot of other things that factor into this so here are some details...

Spa panel will be within a few feet of my main panel in my garage, which is drywalled.
Probably go with a 12-15' power cable to run from spa panel to control panel.
Including option to run 2 elements at the same time so will be pulling 45+ amps occasionally.

I'm going to have someone install the breaker and spa panel but wanted to be able to tell them exactly what I need and why. It's a friend of a friend of a friend type thing so I'd rather be able to have everything ready for them to just install it.

#6 is the way to go. For such a short run, why go with 8? You may save a few dollars but will not technically be "NEC legal". I'd use 6 then when you add a few amps in the future you will not have to worry.

Edit: conduit depends on the application and your local codes. My brewery feed is in conduit but is not required to be...I'm sure that doesn't help you

Thanks Ischiavo! Are you recommending using #6 for both the short run to the spa panel and also for the 12-15' main power cord?

The main reason I'm asking about all of this is safety/code...the other reason is that I'm trying to figure out how I'm going to distribute the power inside my panel. I want my terminal blocks or din blocks to be able to handle the incoming wire size.

summerofgeorge said:

Thanks Ischiavo! Are you recommending using #6 for both the short run to the spa panel and also for the 12-15' main power cord?

The main reason I'm asking about all of this is safety/code...the other reason is that I'm trying to figure out how I'm going to distribute the power inside my panel. I want my terminal blocks or din blocks to be able to handle the incoming wire size.

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Yes, I would use 6 between the breaker and the terminal block in your control panel.

I really like these blocks and have used them in several panels:

http://www.elecdirect.com/product/66f4bb74-feb3-4845-849a-c897ea6ffdbd.aspx

You can run your 6 in and tap off to your fusing. They work nice. I usually put in four for the hots, neutral and ground.

summerofgeorge said:

Thanks Ischiavo! Are you recommending using #6 for both the short run to the spa panel and also for the 12-15' main power cord?

The main reason I'm asking about all of this is safety/code...the other reason is that I'm trying to figure out how I'm going to distribute the power inside my panel. I want my terminal blocks or din blocks to be able to handle the incoming wire size.

Click to expand...

I have 6 running from my panel to the spa to the control panel. Into DINs. The DINs I used can handle the 6# upto 22#. Quick and easy.

electrician here. You need 6 awg for 50 amps

gtmaus said:

electrician here. You need 6 awg for 50 amps

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That is a huge "depends":

http://www.cerrowire.com/ampacity-charts

Depends on the wire rating and conductor rating.

Take a look at the chart.!

P-J said:

That is a huge "depends":

http://www.cerrowire.com/ampacity-charts

Depends on the wire rating and conductor rating.

Take a look at the chart.!

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Of course there's a lot more to it. You need to consider ambient temp, raceway (conduit or open air), number of conductors ampacity derating percentages and insulation type. I was just making it easier for him. I know what I do for a living.

gtmaus said:

...
I know what I do for a living.

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Understood. No problem - However - I took exception to the blanket statement that was made. There is one hell of a lot more to it than that.

It's like the other issue that I have a hard time ignoring. The "percentage rule" for the power draw on a electrical outlet circuit. There is more to it than most "electricians" seem to realize.

Another thing... Never mind - it no longer matters.

P-J said:

Understood. No problem - However - I took exception to the blanket statement that was made. There is one hell of a lot more to it than that.

It's like the other issue that I have a hard time ignoring. The "percentage rule" for the power draw on a electrical outlet circuit. There is more to it than most "electricians" seem to realize.

Another thing... Never mind - it no longer matters.

Click to expand...

no worries here. I was just trying to keep it simple and help. 6 awg is what I would run if it was in my house.

hatrickwah said:

I have 6 running from my panel to the spa to the control panel. Into DINs. The DINs I used can handle the 6# upto 22#. Quick and easy.

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I really like DIN components. They take a lot of work out of mounting things. How did you handle tapping after that block?

lschiavo said:

I really like DIN components. They take a lot of work out of mounting things. How did you handle tapping after that block?

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Tapping after the block?

hatrickwah said:

Tapping after the block?

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Yeah, like say you need to connect 2 10's and 2 14's to the incoming 6.

lschiavo said:

Yeah, like say you need to connect 2 10's and 2 14's to the incoming 6.

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I ran 6# to the din, added enough din blocks to break 3 out of one 6# in and 2 from the other hot. Ran 6# from each to din breakers 2 25a 2 pole and 1 16a 1 pole. From the breakers the wires break down to 10 and 14. Works great. I brought the common 6# straight to the common block and stuck a number of terminal blocks together to create a block with 14, 10, and the single 6 wire. I like breakers, they're easier to install than the fuses, and when they trip, you can reset them easily and therefore protect my hardware.

hatrickwah said:

I ran 6# to the din, added enough din blocks to break 3 out of one 6# in and 2 from the other hot. Ran 6# from each to din breakers 2 25a 2 pole and 1 16a 1 pole. From the breakers the wires break down to 10 and 14. Works great. I brought the common 6# straight to the common block and stuck a number of terminal blocks together to create a block with 14, 10, and the single 6 wire. I like breakers, they're easier to install than the fuses, and when they trip, you can reset them easily and therefore protect my hardware.

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I see. I have opted for the terminals I linked above mainly for cost. There are so many parts available for a DIN setup that I usually just give in to simplicity. Plus the cost seems to add up quickly. I would like to use some breakers next time around though. Where do you source your parts?

Since we're on the topic. I just pulled my permit to wire up the garage. I'm going to use a 30 amp line, however, I'd like to have the option of 50 in the future. Will I get anything other than funny looks from the inspector if I run 6 gauge instead of 10 gauge?

Details: It's a straight shot 30 foot run from my main panel to a 4 prong dryer outlet. It'll be in the wall (need to cut out the sheetrock, then put it back). I'll use a 30a gfci breaker in the panel.

lschiavo said:

I see. I have opted for the terminals I linked above mainly for cost. There are so many parts available for a DIN setup that I usually just give in to simplicity. Plus the cost seems to add up quickly. I would like to use some breakers next time around though. Where do you source your parts?

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I got all of my DIN rail parts from Mouser. They seemed to have the best pricing. The only annoyance was that I had to order DIN rail in a 6' segment, which is both overkill and a hassle to ship. I downloaded a PDF catalog from one of the vendors to make it easier to figure out the right combinations of blocks, dividers, jumpers, etc. I'll see if I saved it.

bolts said:

Since we're on the topic. I just pulled my permit to wire up the garage. I'm going to use a 30 amp line, however, I'd like to have the option of 50 in the future. Will I get anything other than funny looks from the inspector if I run 6 gauge instead of 10 gauge?

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Should be OK. I don't believe the code says anything about upsizing by a few gauges.