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afitz2

join:2009-10-28
Riverton, IL

Whirlpool Tub Wiring

I am going to install a Whirlpool tub in my bathroom. It calls for a dedicated 15 amp circuit with GFCI.

The run from the breaker box is about 100 foot. Will that long of a run be too much for 14 gauge wiring? Should I bump it up to 20 amp with 12 gauge?

Also, which would be better a GFCI breaker or a faceless GFCI device?



Msradell
P.E.
Premium
join:2008-12-25
Louisville, KY

I would definitely run 12 gauge wire for a run that long. The 15 amp breaker should be fine. Either type of GFCI will work. I'd probably go with the faceless but it's really your choice.



whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9

2 edits
reply to afitz2

What does the tub motor draw? In other words, post relevant nameplate information. 20 AWG may not be needed. (A 15 amp load on a 100 foot long run, does require an increase in wire size due to voltage drop. However, you likely don't have a 15 amp load.)

Secondly, while you may bump the wire size up; there is no need to increase the size of the breaker. In fact, there may be code issues with this. How is the unit powered? Via a single receptacle typically, located behind an access door under the tub. Its a code violation to put a single 15A receptacle on a dedicated circuit with 20A breaker.

Let us in on some more of the details, so conclusions aren't hastily jumped to (costing you money you don't need to spend).

I would recommend the faceless GFCI. It sure beats the hidden GFCI receptacle under the tub; or going down to the breaker panel in your sopping towel to reset it.


gregz

join:2009-10-01
reply to afitz2

100 feet? What are you doing, running it clear across one of the trailer parks there in Riverton, or across from the neighbors? I do not think that there are homes large enough to warrant a 100' run.



whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9

1 edit

A 100 foot run of wire is not that unusual in some of today's homes. Think about it; with a 2 story (plus basement) home 55' by 30' and the tub on the second floor in the opposite corner of the house from the breaker panel, and you could easily have 110' of wire.


gregz

join:2009-10-01

In Riverton it is unusual. Those are pretty much small homes, not mansions.


afitz2

join:2009-10-28
Riverton, IL

1 edit
reply to afitz2

I haven't bought the tub yet, I am just doing some initial research.

Here is the manual for the tub: »www.plumbersurplus.com/pdf/15660.pdf

But I don't see any specs for the motor.

Our house is pretty narrow, but long. The breaker box is at the north east of our house, and the bathroom is in the south west. The 100' is more like 90'.


gregz

join:2009-10-01

1 edit

1 recommendation

I personally would run #10 for that length of run, then go with #12 at the junction box for the connecting the outlet for the tub, if it was me. Also keep in mind, with a tub like that, it is better to either install a Water Heater dedicated for the tub, or two water heaters, since a 40 gal tank will get used up real quick if it is filled up. Leaving no hot water for anyone else to use (ie dishes, etc.)



whizkid3
Premium,MVM
join:2002-02-21
Queens, NY
kudos:9

4 edits
reply to afitz2

said by afitz2:

Here is the manual for the tub: »www.plumbersurplus.com/pdf/15660.pdf But I don't see any specs for the motor.
Unfortunately, the manual does not give specs for the motor - just says what size circuit breaker and receptacle are necessary. I will assume you are not installing some of the electrical options, like the heater? Without actually having the motor's name plate data; assume that it is close to a 15A load. (The NEC requirements are a maximum of 3% voltage drop in branch circuits. 3% of 120V, is 3.6V)

I did a few voltage drop calculations, assuming the inductance is negligible (as it will be because this is not in steel conduit I assume). This is what I get for a load of 15A, single-phase, type-NM copper wire, with a maximum voltage drop of 3.6V:

14AWG - 38 feet max
12AWG - 61 feet max
10AWG - 97 feet max

So, go with 10 AWG from the breaker to the first junction box. Then you can transition to 14 AWG. Use a 15A breaker, and a single-receptacle below the tub as shown in the installation manual. Place your GFCI device in an outlet box, somewhere convenient in the room. I suggest keeping it a few feet away from the tub enclosure. If you actually do get the motor name plate data; let me know and I will re-do the voltage drop calculations for you. For all we know, the motor may not even draw 7 amps. It may allow you to use a smaller size wire.
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