Size of wire for Spa..concerned

Old 01-31-04, 03:56 PM
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Question Size of wire for Spa..concerned

Hi everyone, I need to know what size wire should be used for a 230 volt 50amp hot tub?
We were told a #6wg but now the electrician thats going to run the wiring says #8wg would be fine.
The distance from the main breaker to the GFCI subpanel is about 80 ft. (Manufacturer recommends if its under 100ft that #8wg is okay.) I'm concerned about my house burning down, or the wire not being able to handle the load.
Does anyone out there have any ideals or info. Thanks a lot for the help.
Old 01-31-04, 04:54 PM
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Your house will not burn down from #8 on this circuit!

Some things to consider may make it a code violation though.

Is it conduit from the panel to the spa disconnect?
Is there NM (romex) used inside the house?

The conductors used in NM are rated at 90 deg. C.. The ampacity of this wire is 55 amps. Thing is, NM must use the 60 deg column for ampacity which is 40 amps.

#6 THHN @90*c being 55 amps you must use the ampacity column for the lowest temperature rating of any part of the circuit components. Normally this is 75*c..

#8 @75*c is 50 amps.

So, if the run is conduit all the way to the panel #8 is fine as long as all the terminals, etc. are rated for 75*c.

If there is NM run inside the house (which is code legal) you ned to run #6/3 NM.

Sorry if this is a little over complicated.

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