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07-27-2012, 05:26 PM
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#1
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Newbie
Join Date: Jul 2012
Posts: 19
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What size Wire for 70 Amp at 107 Feet
I am running power to an out building for a hot tub. The breaker is 70A the distance from Main to sub is about 107 ft. Conduit is under ground 1 1/4" PVC EMT. What size wire should this be?
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07-27-2012, 05:26 PM
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#2
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Newbie
Join Date: Jul 2012
Posts: 19
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What size Wire for 70 Amp at 107 Feet
More detail
I am having a hot tub house put in. The structure is about 80 feet from the house with a 100 Amp Sub Panel with one 50 Amp circuit for the hot tub, one 20 amp circuit for 4 120vac outlets and one 15 amp circuit for interior and exterior lighting. The contractor doing the work is trying to tell me it is Ok to use #8 wire for the common on a 107 foot run fed from a 70 amp breaker in the main panel in the house. Everything I have read tells me that the two hots and the common need to be #4 wire and the ground a #8. What is right for this application? Every time I build something I always over kill it to ensure safety. Now that I am paying someone else to do it I know they are going to go to the minimums for cost but I don’t want corners cut to save a few pennies.
One other item that has me concerned is the wire run is in 1 1/4" PVC conduit from the Hot tub house sub pane to the hose but then it is not in any conduit going from the house penetration to the main breaker panel. The distance is about 10 feet. Correct me if I am wrong but only Non Metallic Sheathed cable can run without conduit of some sort in the walls and attic space.
I plan to use #8 wire from the Sub panel to the hot tub in flex/water tight conduit. It is about a 10 foot run
If anyone has these answers and can let me know what code to reference I would greatly appreciate it.
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07-27-2012, 05:32 PM
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#3
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E2 Electrician
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 3,102
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by kenb1023
More detail
I am having a hot tub house put in. The structure is about 80 feet from the house with a 100 Amp Sub Panel with one 50 Amp circuit for the hot tub, one 20 amp circuit for 4 120vac outlets and one 15 amp circuit for interior and exterior lighting. The contractor doing the work is trying to tell me it is Ok to use #8 wire for the common on a 107 foot run fed from a 70 amp breaker in the main panel in the house. Everything I have read tells me that the two hots and the common need to be #4 wire and the ground a #8. What is right for this application? Every time I build something I always over kill it to ensure safety. Now that I am paying someone else to do it I know they are going to go to the minimums for cost but I don’t want corners cut to save a few pennies.
One other item that has me concerned is the wire run is in 1 1/4" PVC conduit from the Hot tub house sub pane to the hose but then it is not in any conduit going from the house penetration to the main breaker panel. The distance is about 10 feet. Correct me if I am wrong but only Non Metallic Sheathed cable can run without conduit of some sort in the walls and attic space.
I plan to use #8 wire from the Sub panel to the hot tub in flex/water tight conduit. It is about a 10 foot run
If anyone has these answers and can let me know what code to reference I would greatly appreciate it.
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Almost EVERY hot tub i've ever wired called for # 6 AWG MIN. for all the conductors...(two hots, neutral and grounding conductor) so check the hot tubs requirements first! Also, you better read article 680 for the rest of this installation and find out what code cycle of the NEC you are on... Two items I NEVER consider DIY, one being a pool, the other a hot tub.
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Last edited by stickboy1375; 07-27-2012 at 05:37 PM.
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07-27-2012, 05:42 PM
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#4
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Licensed Electrical Cont.
Join Date: Feb 2004
Location: NY State
Posts: 6,164
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What size Wire for 70 Amp at 107 Feet
Are you telling us he is intending to run the THHN conductors in free air in the house to the main panel?
WHO is this "contractor"?
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The Following 2 Users Say Thank You to Speedy Petey For This Useful Post:
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07-27-2012, 05:42 PM
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#5
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E2 Electrician
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 3,102
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by Speedy Petey
Are you telling us he is intending to run the THHN conductors in free air in the house to the main panel?
WHO is this "contractor"?
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Obviously not the electrical contractor.... 
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The Following User Says Thank You to stickboy1375 For This Useful Post:
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07-27-2012, 05:45 PM
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#6
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Newbie
Join Date: Jul 2012
Posts: 19
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by stickboy1375
Almost EVERY hot tub i've ever wired called for # 6 AWG MIN. for all the conductors...(two hots, neutral and grounding conductor) so check the hot tubs requirements first! Also, you better read article 680 for the rest of this installation and find out what code cycle of the NEC you are on... Two items I NEVER consider DIY, one being a pool, the other a hot tub.
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The instructions did not call out for a wire size. All it had was a 50A breaker was needed. When I looked up 50A feeds in my electrical book it called for #8 in conduit under 40 feet or #6 Romex cable. For this short run It won't cost much more to run #6.
Do you have any advise on the othere questions?
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07-27-2012, 05:47 PM
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#7
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E2 Electrician
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 3,102
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by kenb1023
The instructions did not call out for a wire size. All it had was a 50A breaker was needed. When I looked up 50A feeds in my electrical book it called for #8 in conduit under 40 feet or #6 Romex cable. For this short run It won't cost much more to run #6.
Do you have any advise on the othere questions?
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Read article 680 of the NEC, hot tubs are involved, electrically speaking.
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07-27-2012, 05:48 PM
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#8
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Newbie
Join Date: Jul 2012
Posts: 19
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by stickboy1375
Obviously not the electrical contractor.... |
The General going by the instructions of his electrican. I knew this wrong but all my electrical background is industrial/Navy
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07-27-2012, 05:51 PM
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#9
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E2 Electrician
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 3,102
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by kenb1023
The General going by the instructions of his electrican. I knew this wrong but all my electrical background is industrial/Navy
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It would depend on your total load....
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07-27-2012, 05:55 PM
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#10
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Licensed Electrical Cont.
Join Date: Feb 2004
Location: NY State
Posts: 6,164
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by kenb1023
The General going by the instructions of his electrican. I knew this wrong but all my electrical background is industrial/Navy
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Why not hire a real electrician to do this job?
And you n ever answered my question about inside the house.
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Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
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07-27-2012, 05:58 PM
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#11
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Newbie
Join Date: Jul 2012
Posts: 19
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by Speedy Petey
Why not hire a real electrician to do this job?
And you n ever answered my question about inside the house. |
I hired a general to do the build. I anticipated them bring in an electrician for the wiring.
As for in the house, they are not using any conduit at all. This I know is very wrong.
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07-27-2012, 05:59 PM
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#12
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E2 Electrician
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 3,102
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by kenb1023
I hored a general to to the build. I anticipated them bring in an electrican for the wireing.
As for in the house they are not using any conduit at all. This I know is very wrong.
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They have to be, 680.25 (A)
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Last edited by stickboy1375; 07-27-2012 at 06:01 PM.
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07-27-2012, 06:07 PM
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#13
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Newbie
Join Date: Jul 2012
Posts: 19
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by stickboy1375
They have to be, 680.25 (A)
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In the tub house everything is in conduit or Romex in the ceiling. In the main house (Actually the attached garage) they did not use any conduit. Just the three wires ran inside the wall cavity.
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07-27-2012, 06:09 PM
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#14
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E2 Electrician
Join Date: Apr 2012
Location: Litchfield, CT
Posts: 3,102
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by kenb1023
In the tub house everything is in conduit or Romex in the ceiling. In the main house (Actually the attached garage) they did not use any conduit. Just the three wires ran inside the wall cavity.
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3 wires? you need four, sounds very hacked...
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07-27-2012, 06:11 PM
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#15
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Newbie
Join Date: Jul 2012
Posts: 19
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What size Wire for 70 Amp at 107 Feet
Quote:
Originally Posted by stickboy1375
3 wires? you need four, sounds very hacked...
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They say since the out building has it's own grounding rods the 4th is not needed.
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