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-   -   Wire ampacity for new Hot Tub Install (http://www.diychatroom.com/f18/wire-ampacity-new-hot-tub-install-170737/)

HutchNJ 02-01-2013 10:03 AM

Wire ampacity for new Hot Tub Install
 
Hi guys, I recently purchased a hot tub wihich is name plated at 50amps(seems typical for most now even though this is a lower end model). Based on the math it maxes out at a bit less than 40 amps with everything on at once. Here's my dilema, the cable from the outside GFCI panel to the area where the hot tub will be has been prewired with #8/3 UFB. I still have to run the cable from the panel in my house to the GFCI panel as well as terminate the UFB at the tub and run sealtite to the ub panel. The UFB insulation is rated at 90C. If I use terminations at both ends rated at 75C can I use this on a 50 amp circuit? Assuming that my wiring from my main panel to the GFCI and the UFB termination to sealtite to the tub are rated 50amp?

busman 02-01-2013 10:13 AM

You're going to have to replace that cable anyway. UF cable is not permitted for outside wiring to a Spa.

Mark

HutchNJ 02-01-2013 10:29 AM

If the UF cable comes out of the ground in PVC to a box why can't I run sealtite with individual wires to the hot tub panel?

busman 02-01-2013 10:38 AM

680.21. 2005 NEC. I don't have the 2011 with me.

Mark

Techy 02-01-2013 10:52 AM

Quote:

Originally Posted by busman (Post 1107148)
680.21. 2005 NEC. I don't have the 2011 with me.

Mark


Same article in 2011.


680.21 Motors.



(A) Wiring Methods.

The wiring to a pool motor shall com-
ply with (A)(1) unless modified for specific circumstances by
(A)(2), (A)(3), (A)(4), or (A)(5).


(1) General. The branch circuits for pool-associated mo-
tors shall be installed in rigid metal conduit, intermediate
metal conduit, rigid polyvinyl chloride conduit, reinforced
thermosetting resin conduit, or Type MC cable listed for the
location. Other wiring methods and materials shall be per-
mitted in specific locations or applications as covered in
this section. Any wiring method employed shall contain an
insulated copper equipment grounding conductor sized in
accordance with 250.122 but not smaller than 12 AWG.


The ground in UF Cable is bare, not insulated. Therefore not compliant.

HutchNJ 02-01-2013 11:13 AM

Thanks for all your help. Looks like some rework. Last question, what is the max distance the GFCI disconnect can be from the tub. I know it's no closer than 5ft but I see a lot of different answers on the max.

thanks

Speedy Petey 02-01-2013 03:46 PM

Quote:

Originally Posted by HutchNJ (Post 1107171)
Thanks for all your help. Looks like some rework. Last question, what is the max distance the GFCI disconnect can be from the tub. I know it's no closer than 5ft but I see a lot of different answers on the max.

thanks

You probably won't find a maximum quoted, but typically within sight and/or 50' is a rule of thumb.

HutchNJ 02-01-2013 07:06 PM

I don't mean to beat this to death but this seems like UFB is suitable. This from NEC 2005 section 680.42.
"
any of the
wiring methods recognized in Chapter 3 of this
Code that contain a copper equipment
grounding conductor that is insulated or enclosed within the outer sheath of the wiring method
and not smaller than 12 AWG shall be permitted to be used for the connection to motor,
heating, and control loads that are part of a self-contained spa or hot tub or a packaged spa or

hot tub equipment assembly." What do you guys think?

k_buz 02-01-2013 07:49 PM

What code cycle are you on? If you don't know, at least tell us what state you are located in.

HutchNJ 02-01-2013 07:51 PM

New Jersey

k_buz 02-01-2013 08:02 PM

New Jersey is on the 2011 code cycle so you are out of luck on the UF. The ground must be insulated.

As a word of warning. There are a multitude of codes concerning hot tubs...from needing a GFI receptacle to equipotential bonding grid. Since water and electricity do not mix well, I HIGHLY suggest you consult a licensed electrician, pull a permit, and have it inspected. A hot tub isn't something you simply wire up like an AC compressor.

Jim Port 02-01-2013 08:07 PM

Article 680.42(c) applies to the interior portions of the circuit. Outside needs an insulated ground.

Stubbie 02-01-2013 08:45 PM

Quote:

Originally Posted by HutchNJ (Post 1107115)
Hi guys, I recently purchased a hot tub wihich is name plated at 50amps(seems typical for most now even though this is a lower end model). Based on the math it maxes out at a bit less than 40 amps with everything on at once. Here's my dilema, the cable from the outside GFCI panel to the area where the hot tub will be has been prewired with #8/3 UFB. I still have to run the cable from the panel in my house to the GFCI panel as well as terminate the UFB at the tub and run sealtite to the ub panel. The UFB insulation is rated at 90C. If I use terminations at both ends rated at 75C can I use this on a 50 amp circuit? Assuming that my wiring from my main panel to the GFCI and the UFB termination to sealtite to the tub are rated 50amp?

UFB can only be used under the 60c column of table 310-16 for ampacity which is in your case 40 amps. Can't use the ampacity under the 75C column or the 90C column which is used for derating ampacity purposes.

I'm not sure what "based on the math means' ? Your wire ampacity must meet the nameplate electrical requirements of the spa.

Stubbie 02-01-2013 08:49 PM

Quote:

Originally Posted by HutchNJ (Post 1107555)
I don't mean to beat this to death but this seems like UFB is suitable. This from NEC 2005 section 680.42.
"
any of the

wiring methods recognized in Chapter 3 of this
Code that contain a copper equipment

grounding conductor that is insulated or enclosed within the outer sheath of the wiring method

and not smaller than 12 AWG shall be permitted to be used for the connection to motor,


heating, and control loads that are part of a self-contained spa or hot tub or a packaged spa or





hot tub equipment assembly." What do you guys think?


You forgot the subsection title ..... :wink:


(C) Interior Wiring to Outdoor Installations.
In the interior
of a one-family dwelling or in the interior of another
building or structure associated with a one-family dwelling,
any of the wiring methods recognized in Chapter 3 of this

Code
that contain a copper equipment grounding conductor
that is insulated or enclosed within the outer sheath of the
wiring method and not smaller than 12 AWG shall be permitted
to be used for the connection to motor, heating, and control
loads that are part of a self-contained spa or hot tub or a
packaged spa or hot tub equipment assembly. Wiring to an

underwater luminaire shall comply with 680.23 or 680.3

HutchNJ 02-04-2013 07:03 AM

Thanks again guys,
I'll verify this with my locality but in the short term here's my plan,
For a 50amp circuit to the hot tub I'll run #6 NMB inside my basement then a JBox to individual #6 conductors in PVC and flex under my deck structure to my GFCI panel then individual #6 conductors in metal conduit underground to the tub. (metal conduit so I only have to go 6in undersground and to go much more than that around here is difficult)


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