sub panel feed and branch circuit from sub panel in same

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royta

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I appreciate your patience, as there are many areas of the NEC that I don't know.

With a 50A sub panel, specifically one used for a spa or hot tub, can you supply the sub panel and then supply the spa from the sub panel through a short common piece of conduit?

The conduit is routed from the main electrical panel to an LT. One hub goes to the sub panel, and the second hub goes to the spa. Is there anything in the code prohibitting this?

Thanks. -Roy

*edited to check the email notification box*

[ September 09, 2004, 02:36 PM: Message edited by: royta ]
 
Re: sub panel feed and branch circuit from sub panel in same

Roy,

What type of contractor are you?

As long as all of the line and load conductors, including the grounded conductors, are routed together, there is no violation.

[ September 09, 2004, 02:13 PM: Message edited by: peter d ]
 
Re: sub panel feed and branch circuit from sub panel in same

Electrical Contractor in California. I was issued my license in June of this year. Unfortuantely, my qualifying work was from years past, but within the 10 year limitation. Because I'm a new contractor, doesn't mean I slam out an installation full of violations. I research everything I do, to make sure I'm doing everything right. I have a habit of overthinking everything I do. Thirteen years ago when I used to handload for my .22-250 rifle, all I did was read and learn about the subject. I guess I'm saying all of this because I want to clear up any misjudgements that might be made about me for being such a rookie. :)

I'm not sure what you mean by "routed together" in your response. In the 1" conduit, between the LT and the sub panel, my plan was to install six #6's (three in and three out), and two #10 grounds (one in and one out). Actually, I might install a 1 1/4" LT, with reducing bushings on two of the hubs, and run five feet of 1 1/4" EMT to the sub panel, as six #6's and two #10's might be a little tight.

Thanks again.

Roy
 
Re: sub panel feed and branch circuit from sub panel in same

Don't forget to derate the current carrying capacity of the conductors in that 5 foot section. Check out 310.15(B)(2)(a).
 
Re: sub panel feed and branch circuit from sub panel in same

routed together = run in the same conduit

Otherwise, there would be no cancellation of the magnetic field (a changing current produces a changing magnetic field. Inductive heating would occur in metallic raceways and enclosures, as well as electo magnetic interference.
 
Re: sub panel feed and branch circuit from sub panel in same

Thanks earlydean.

Well, I know the wire is rated over 60C (THHN), but I'm not positive on the devices on either end. The 50A main sub panel feed will be on either a GE THQP or THQL GE breaker. I get this from the GE website , "65oc/75oc Conductor Rating". That doesn't really nail it down to 75C does it? The spa sub panel is a Cutler Hammer mod # CH50SPA. It is a 4 circuit sub panel with an included 50A GFCI main, with space for two 1-pole breakers, one on either side of the main. I can't find anything but the instructions at the Cutler Hammer site, but according to page 3-5 on this .PDF file, CH loadcenters are suitable for 60/75C rated wire.

At 75C, #6 is good to 52A after taking into consideration 310.15(B)(2)(a). Am I at 75C though?

Thanks again. -Roy

*you snuck in peter d. Thanks for the reply.

[ September 09, 2004, 04:14 PM: Message edited by: royta ]
 
Re: sub panel feed and branch circuit from sub panel in same

Rule of thumb = When in doubt, use the 60 C amapcity.

Also, you must go with the "weakest link" principle.

Remember, the 90 C column can be used for derating purposes, so you start there and work your way down (derating for # of conductors and temperature corrections), as long as you don't exceed the 60 C amapcity.
 
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