hot tub install (NEC2005)

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Old 06-15-09, 03:20 PM
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hot tub install (NEC2005)

My city goes by NEC 2005. Few questions... but first what I am doing.

6/3 (3x #6s and a ground) from a sub panel in my garage (60amp breaker) above the garage (in the attic) and then outside, down about 5ft to my GFCI/disconect box. I plan to use metal conduit down to the box, it is 6-7ft away from the hot tub. The hot tub already has a 6-7 foot pig tail, that is in a flexible PVC stuff. I plan to use a water tight connector on the end of it to go into the side of my disconnect box. I plan to mount the box about 48inches off the ground.

1) From what I understand the 5ft or so of vertical run down to the box, as long as I use sealed adapters(PVC with liquidtight, etc, or metal with a compression join) I can use the "indoor" type wiring. (per another thread on this site). Is this true? I don't seen any other way to transition from indoor to outdoor #6 wire, other wise i would need a huge 30cu-in junction box when the wire first leave the house about 10 feet off the ground to switch to outdoor wire for the remaining short 5ft down.

2)The box is designed as spa disconnect, and has a lockable cover. When standing at the box, i can see the entire access area for the pumps, and about 20% of the tub. Same goes from in the tub, if I was sitting in it I could only see the box directly if I was sitting in the back of it. From what I ready, this could be a "grey" area, but since the box can be locked during servicing it is probably ok. I am kind of forced to do this, or I will have to mount the box a LOT farther and run a LOT of conduit and wire! (hard to explain with out knowing how my lot is laid out).

3) I have a window that is 4.25ft away from the hot tub interior wall. I assume I will need to bond the window. What is the trick to doing that?

4)do i need a "clamp" entering the conduit that will run down from the attic wall, outside to the box?

5) see anything else wrong, or common mistakes people make?

Thanks!
 

Last edited by jordonmusser; 06-15-09 at 04:02 PM.
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  #2  
Old 06-15-09, 04:03 PM
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You'll need to make a junction before the NM cable leaves the house. Code specifically states in the interior.

You can use the EMT with compression fittings, or PVC where you come down the wall but, you'll need an insulated ground in it. NM cannot be run in conduit outside. So you can put a JB in the attic?

The conduit needs to be strapped within 3' of any box/fitting, etc. and within 10' thereafter.

As far as the window, well, I'd rather not say because I personally think it's kinda stupid to have to bond a window(if it's metal) I'd move the hot tub if you can the other 9". If you do it, I'll say to grind a little paint off, drill through it, take a brass lug with stainless steel nut and bolt and run # 8 to it

Hope this helpsBeer 4U2
 
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Old 06-15-09, 04:35 PM
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Great, thanks! I need to get as many issues worked out before I pay an electriction to come inspect, as I am sure he will find other issues.

The only 6awg JB i have found at the local home improvement places is either a spa disconnect (unfused). it's only 10 bucks, I guess i can use that since I can't just use wire nuts with 6awg Since I am running through conduit, do I go to seperate wires? I can run a smaller ground than 6awg correct?

Another Q, some what related.

I have a sub panel. It is fed by a 100amp breaker, from the main panel. They are next to each other, and it was installed with 6awg also, maybe 12inch long (just goes thru the stud and into the sub box). From reading the NEC, this should be #2.
so 1) This is a short run, so the Vdrop should be low.. but i still have to run #2 per code and 2) can I even install #2awg into a breaker?
 
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Old 06-15-09, 05:16 PM
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Sounds like your sub was rated at 100 amps but fed from a 50 or 60 in the main. This just means it cannot be fed with more than 100 amps.

There are wirenuts and other connectors that can be used with #6. Most seem to be a large blue or gray wirenut.
 
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Old 06-15-09, 05:58 PM
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ironically, the hot tub was removed from a house where it had been installed as a new built (and presumably to code).

but when I just checked the 6ft long pig tail that was attached to the tub- no insulated Ground :-/
 
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Old 06-15-09, 07:58 PM
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Originally Posted by jordonmusser View Post
I can use the "indoor" type wiring. (per another thread on this site). Is this true?
Not for a spa -- the exterior wiring must have an insulated ground.

I recommend that you run 3/4" or 1" flexible PVC (a.k.a. ENT, electo non-metallic tubing, smurf tube) from your subpanel through the interior of your building and poke it out through the exterior wall. You can then glue on an LB fitting and switch to a vertical rigid PVC conduit down to the disconnect. This is a fully assembled conduit system which you can then pull the continuous conductors in without splices.

Note, you may also be able to use #8 conductors instead of #6 with the conduit. What is the exact electrical requirement of the tub?

When standing at the box, i can see the entire access area for the pumps,
Sounds okay to me.

3) I have a window that is 4.25ft away from the hot tub interior wall. I assume I will need to bond the window. What is the trick to doing that?
It is not required. Bonding is only required for surfaces "likely to become energized" such as those with electrical components like lights, pumps, heaters, etc. I do not see how that would be likely for a typical window frame.

5) see anything else wrong, or common mistakes people make?
The ground wire must be copper, insulated green -- probably the most common spa mistake.

I can't just use wire nuts with 6awg
You can -- Ideal large blues can take (2) #6 copper.

Since I am running through conduit, do I go to seperate wires? I can run a smaller ground than 6awg correct?
Yes, separate wires are preferred in conduit: black, red (or black), white and green. If your tub install manual requires 50A or less you can use #8 for the hots and neutral. At 50A - 60A you need the #6. The ground can be #10 in either case.
 
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Old 06-15-09, 08:14 PM
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wow, thanks for the detailed response. So if I run conduit from the sub, I can run 4 individual wires the whole run?

I already own a spool of the 6/3 that is obviously unacceptable, so can I remove the insulated black/red/white and just go buy a single green insulated copper conductor and run it along with those in the conduit? Would save a ton of money since I already own the 6/3.

one more (i swear ill run out of questions soon):
One of the original house 110v circuits was moved to the sub panel, and instead of trying to find the neutral or ground in the mess of wires only the hot was taken over to the sub panel (only ~12inches away or so). Do I need to find the neutral and ground that goes with that circuit and move it also? its REALLY tough to find since it is some original wiring from 20 years ago. Beer 4U2
 
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Old 06-15-09, 08:30 PM
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Your inspector may have an issue with stripping the conductors out of the jacket. A cable is listed as an assembly. stripping the sheath breaks up the assembly and the conductors are not labeled with their size or insulation ratings.

Yes, the neutral should have been moved over to where the hot conductor originates.
 
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Old 06-15-09, 09:54 PM
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ok, thanks to ya'lls input, here is what I plan to do (primarily because I already have the 6/3... and b/c of where it is routed). I might add that I am running 2 other 14/2 circuits with it, one is an existing GFI light and one is a new GFI circuit from my new breaker/disconnect box(spa box):

(when I say 6/4 I am refering to 4x6awg individual conductors, and 14/3 I am refering to an outdoor specfic wire bundle)

from orig breaker box, 6/3 through my attic into a 6x6x6 JB (question: this is big enough right, for making the dry/wet wire junction with 1x 6/3 and 1x 14/2?) along with a 14/2 from another source. change over to outdoor cable here on each(6/4 and 14/3 respectively). down a 1.25" conduit (with 6/4 and 14/3) to my GFI outdoor breaker(spa box). the 6/4 goes through the GFI circuit(spa box), the 14/3 passes through and along with a new 14/3 that comes off the GFI box here(spa box), and both the 14/3s head out via a 3/4" PVC conduit, down 18"inches under the ground and off to where those 2 circuits need to be. The 6/4 off the GFI breaker heads down through a 1" PVC conduit, 18" under the ground, over 6-7 feet to the box where my pumps are where it comes out of the ground, and switches to flex-conduit which goes into the control box.

The only thing I don't have on hand is the 6x6x6 box, the 6/4 and the 6awg wire nuts.
 
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Old 06-16-09, 12:47 PM
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Originally Posted by jordonmusser View Post
when I say 6/4 I am refering to 4x6awg individual conductors
We would usually call that THHN / THWN which is the type of individual wires you install in conduit.

and 14/3 I am refering to an outdoor specfic wire bundle
And that one is UF-B (or just UF). It means underground feeder and it is a cable assembly which is waterproof and resistant to sunlight. It's usually gray in color.

Compare that to the indoor cable which is NM-B (non-metallic) commonly called Romex.

With both NM and UF it's a little confusing because 14/2 actually has three wires: black white and bare. They don't count the bare wire when numbering the cable.

question: this is big enough right, for making the dry/wet wire junction with 1x 6/3 and 1x 14/2?
It should be okay.

My personal preference would be to keep the tub circuit in separate junction boxes from the general-purpose circuits. I'd use a 4-11/16" square box with flat cover to splice the tub conductors just because it's cheaper than a 6x6. Some of the home stores don't carry 4-11/16" boxes though.

The general-purpose #14 circuits can be spliced in a regular double gang or 4x4 junction box.

The big problem with combining the circuits into a shared conduit is that it requires you to calculate the derating on each circuit and possibly upsize the wires. To avoid the hassle of doing that, I would separate them into separate boxes and conduits.
 
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Old 06-16-09, 01:00 PM
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Thanks for the feedback and info. I think I am all set, I will be sure to post pictures when I am complete. Beer 4U2
 
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Old 06-16-09, 06:13 PM
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Question concerning running the 220v and one 110v in the same conduit..

It appears if I am reading table 310.15(B)(2)(a) right, that this would be 3 conductors and not subject to the derating, except unless paragraph (4)(b) counts? I am not sure I understand what it is saying.
 
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Old 06-16-09, 06:34 PM
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Sorry but you are not reading the table correctly. Both the "hot" and "neutral" conductors are current carrying conductors so you have four (or five if the three number 6 conductors make a 240/120 circuit) current carrying conductors. You do not count the equipment grounding conductors as they do not carry current except under a fault condition.

Paragraph (4)(b) concerns a "neutral wire in a three phase system when only two of the three "hot" conductors are being used.
 
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Old 06-16-09, 06:49 PM
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Okay, my previous post is not entirely correct. (My hands felt "dirty" so after washing them my brain is functioning better.)

In a "multi-wire branch circuit (MWBC) the "neutral" conductor ONLY carries the unbalanced current of the "hot" conductors and in this case the neutral is ignored when counting "current carrying" conductors. In a normal two-wire circuit, whether a combination of "hot" and "neutral" in a 120 volt circuit or two "hot" conductors in a 240 volt circuit ALL the conductors are "current carrying" conductors.


SO, the three wire (240/120) volt circuit made up from the three #6 conductors is two current carrying conductors and the two wire (120) volt circuit made up from the two #14 conductors is also two current carrying conductors for a total of four current carrying conductors. Four through six current carrying conductors require derating to 80% of the maximum current carrying capacity for the insulation on the conductors. If all the conductors are insulated with THHN then you would derate from the 90 degree Celsius column If you are using the dual rated THHN/THWN in an application requiring the THWN designation you would use the 75 degree Celsius column for the derating. To derate you multiply the applicable Ampacity times 0.80.
 
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Old 06-16-09, 07:42 PM
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Makes sense, because obviously the 220v is carrying seperate phases that are 180* out from each other.

I will stick to seperate conduit for the 220v and 110v, it will look a little uglier (both on outside of house) but I even though I am pretty sure even derated it will be ok- I don't want to have to argue with the inspector and show him calculations over 5ft of conduit.
 
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Old 06-16-09, 08:20 PM
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Actually, even using the 75 degree C. column the derated capacity of #6 is 52 amperes and the derated capacity of #14 is 16 amperes. Using a 50 ampere circuit breaker for the #6 and a 15 ampere circuit breaker for the #14 is completely acceptable with having all wires in the same conduit. Just be sure to use type THHN/THWN insulated conductors.
 
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Old 07-27-09, 01:51 PM
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Just wanted to thank everybody for their help. I passed inspection the first try, and the inspector was impressed for a home owner.

I installed:
sub box in garage
GFI sub box/disconnect outside.
1 220v for the hot tub
1 110v for constant power for outdoor kitchen
1 110v switched from inside for additional outdoor lights.

hot tub/deck is done and i am 85% done with the kitchen. Ill post pics when I am all done!
 
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Old 07-27-09, 02:38 PM
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Thanks for letting us know.
 
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