Service Pole to Well House Underground Line Specs


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Old 12-18-11, 10:35 AM
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Service Pole to Well House Underground Line Specs

I am going to start digging a trench to run underground cable from a service pole breaker box to a well house; the distance is 60 feet. The breaker is a 240 V 2-pole 20-20 which will run to the well house water pump pressure switch. The present UF 2-10 AVG with ground cable runs two inches under the ground in the wrong direction and splices somewhere to a yellow TW-INS 10 three wire where it comes out in the well house. As the cable, disconnected and capped, throws the breaker, this seems why we can't keep the breaker on. At night, the breaker stays on for an hour or two with the ground frozen, and then with midday thaw, I can't keep the breaker on. An electrician came out and did not find a short with a multi-meter, but did not use a megger. Even if it is the control box capacitor or relay, I want to upgrade this old cable situation and have a straight, protected run. Hiring a electrician to come out with a megger will be the cost of the job.

How deep should the trench be? 12 inches? What plastic conduit is best? Is gluing enough for the seal? I read that the yellow submersible 600V TW-INS 10 AWG line is good for conduit. I would like to run additional wire for a socket; should that be 12 gauge black and white with ground?

Thanks for any advise! The full story is in the well section. I am moving over here for the underground line. Thanks!

http://www.doityourself.com/forum/we...eaker-off.html
 
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Old 12-18-11, 11:19 AM
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Thanks to Ray. You must not have seen Ray's reply at the other thread.

A multimeter only uses about 3 volts to test the cable. A Megger uses hundreds of volts. The cable may not break down under low voltage. Burial depth for UF cable is 24". Burial depth for PVC conduit is 18". Burial depth for RMC is 12". If you use conduit you use individual THWN wires. Conduit has the advantage of easy replacement of the wires if they fail in the future.
 
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Old 12-18-11, 12:42 PM
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Just to add more. If you are running wire in conduit, run a white one for a neutral, for a total of 4 wires, possibly black, red, green and white. That way you can have a light or heat tape in your well house.
 
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Old 12-18-11, 12:45 PM
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And, individual strands are easier to pull. If you want to run UF cable in a PVC conduit it helps to lubricate the wire. You're right on the border line of what I like to simply shove into a conduit. If going longer distances I tie a small foam ball or foam ear plug to some light kite string and blow it through the conduit with an air compressor or leaf blower. Then use the kite string to pull a heavier cord that you attach to the end of the wire. Then you can have one person on each end of the conduit. One pushing the wire and the other pulling.
 
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Old 12-18-11, 01:42 PM
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What plastic conduit is best?
Schedule 40 is fine unless you are going under a road.
Is gluing enough for the seal?
Yes but sealing isn't the real purpose. It is to hold it together. All conduit eventually fills with water.
I would like to run additional wire for a socket; should that be 12 gauge black and white with ground?
If you go with cable use 10-3 if you go with individual conductors as Chandler suggested use 2 blacks (or a red and a black), a white, and a green. You will need a 60 amp subpanel at the well house. In the subpanel use a a 20 amp 240v breaker for the pump and a 20a 120v breaker for the other circuits.

Since you are going to use #10 I would suggest a 30a 240 breaker at the pole if you use a subpanel at the pump. Subpanel will need a bonded ground bar added, neutral bar isolated, and an eight foot ground rod. (Not as complicated as it sounds. Ask for clarification on anything you don't understand.)
 
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Old 12-18-11, 05:13 PM
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18 inches deep with PVC conduit is what I am going with. Dug down 14 inches today and snow coming tomorrow. I will go with the 10 gauge wire to maintain what was originally there.

I will run the Schedule 40 (no road); glue the sixty foot line and then run wire through; individual wires, two blacks, white, and ground.
Will follow directions for pulling wire: used to do it a decade ago wiring workshops.

Adding a 120V line with the 70 foot run of wire, and running a light, twelve feet of heat tape, and possibly a livestock tank water heater (which is about a 7 amp draw when activated), should I run 10 gauge wire to the well house for the 120V outlet? I think this was answered in ray's thread. I had been told that 12 gauge will only have a 3 percent drop for 60 feet; is it better to go with 10 gauge for the 120V?

Looks like ray2047 is suggesting a sub-panel for the 120 V line and the pump. This will work perfect as I have an extra sub-panel and will separate ground and bond bars at sub-panel. 240V 2-Pole will 30-30 amp breaker will replace current 20-20 amp breaker at main box. This will be a clean job. Thanks and will update!
 

Last edited by ChollaBob; 12-18-11 at 06:55 PM.
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Old 12-18-11, 05:39 PM
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will 30-30 amp breaker will replace current 20-20 amp breaker at main box. Makes sense.
That would be a 30 amp 2 pole breaker, not 30-30 amp breaker. I think it's just a terminolgy difference.
 
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Old 12-18-11, 06:40 PM
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separate ground and bond bars at sub-panel
Just to be clear only the ground bar is bonded.
 
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Old 12-18-11, 07:13 PM
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Just to clarify, you can't have two separate feeders to the well house; so you can not run three 10ga (H/H/N) and 12ga (H/N). Instead, you can run one 30A 10ga feeder (H/H/N/G), then install a subpanel which would power the 20A pump and a 15A circuit for lights/etc.
 
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Old 12-19-11, 07:46 AM
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Thanks for pointing out not to run separate feeder wires as that's what I was going to do before the sub-panel idea!

I worked with the main breaker panel this summer; bonding and grounding are connected only at one point (main breaker here) and sub-panels have separate ground and neutral bars.

30 Amp 2 Pole Breaker will go into the main box to feed the sub-panel. Digging in a blizzard today! Thanks.
 
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Old 12-19-11, 03:14 PM
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The 120V circut also needs GFCI protection.
 
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Old 12-20-11, 05:06 PM
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GFCI for a well house makes total sense. I had asked the electrician about the Arc Fault Circuit Interrupters and he said they have become a standard here in NM. I asked at the hardware store and they said they don't stock them. Sounds like great protection, especially for a trailer as they burn up in about 15 minutes. Are the AFCI circuit breakers in common use now?
 
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Old 12-20-11, 05:13 PM
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Originally Posted by ChollaBob View Post
GFCI for a well house makes total sense. I had asked the electrician about the Arc Fault Circuit Interrupters and he said they have become a standard here in NM. I asked at the hardware store and they said they don't stock them. Sounds like great protection, especially for a trailer as they burn up in about 15 minutes. Are the AFCI circuit breakers in common use now?
AFCI's are only used in dwellings, not outside them.
 
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Old 12-20-11, 06:01 PM
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While the AFCI protection is not required by the NEC there is no reason that the minimums cannot be exceeded.
 
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Old 12-20-11, 08:18 PM
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So AFCI breakers would be installed in the house or trailer interior sub-panel, never on the outside service pole.

For the future well house sub-panel, I would like to install a GFI breaker instead of the GFCI outlet. Right now, the third main pole breaker, a 15 amp breaker, is on the blink. Outside light and horse water tank heater off. The breaker appears on, but is loose when flipping. After a couple of switchings, it snaps on and turns on heater and light for awhile. The pole outlet is GFCI and it is hard to reset in freezing conditions. I would rather have a GFI breaker than the outlet, outside. if that's OK, I will replace 15 amp breaker with 15 amp GFI and ancient GFCI outlet with exterior standard metal outlet tomorrow.

As I only have two single spaces left in this box, can I up the amps on the single breaker and wire a run of two exterior outlets on the pole?

On the ground, bonding, and neutral, I should research further. My working idea of it is that at one point in the grounding chain, in this case my main pole breaker box, neutral and ground can share the same ground bus bar, which creates a backup grounding system called bonding. All following sub panels have separate ground and neutral bus bars with no connection between them. I am sure some comments will follow that definition! I usually research a week before proceeding.
 

Last edited by ChollaBob; 12-20-11 at 08:37 PM.
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Old 12-21-11, 04:46 AM
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Yes, installing a GFI breaker is acceptable in place of using a receptacle as long as the outdoor and wet locations are protected. Aside from the cost I like the breakers better. GFCI's take up so much space in the box that it can be difficult to cram all the wiring back in there and with the GFI protection at the panel it is protecting the wiring on the way to the outlets. Nice protection in case you are doing some wiring work in the future and forget to turn off the power.
 
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Old 12-21-11, 06:17 AM
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I noticed the GFI breakers were more expensive, but seems like a much cleaner way to go. The exterior GFCI outlet seems to be compromised by the weather. I will buy some new weather proof outlets. Thanks.
 
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Old 12-21-11, 06:29 AM
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Most areas now require the large weatherproof enclosures over outside outlets. The old rules allowed for a simple flat, gasketed cover. The new requirement is for a biggish box that allows items to remain plugged in while the cover is closed. They work OK but boy are they ugly.
 
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Old 12-21-11, 07:03 AM
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I am purchasing 80 foot run of wire today. Is individual strand 10ga or UF 3 wire with ground preferred for running through 1 inch of Schedule 40?
 
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Old 12-21-11, 07:19 AM
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I have pulled #10 UF through conduit and it can be done. I like it because of the additional wire protection but it is not as easy to pull as individual conductors but if you have 10 or 20 foot sections of pvc it should not be difficult.

If you get UF carefully unroll the wire. Lay one end on the ground and hold it down. Then walk backwards uncoiling the wire with no twists or kinks. Without kinks or twists you should be able to shove it through each pipe section pretty easily. Conduit systems need to be complete end to end before installing the conductors.

Changes in blue by Mod.
 

Last edited by pcboss; 12-22-11 at 06:42 PM.
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Old 12-21-11, 07:19 AM
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Best practice with a full conduit installation is to use individual THWN conductors. You will need two black, one white, one green (or bare). Don't forget to buy lube.
 
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Old 12-21-11, 07:55 AM
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Individual THWN will be the way to go. In the well house, with a 4 foot conduit riser to the sub-panel, what is the best way to span the gap from the sub-panel to the water pump pressure switch (about a foot off the ground)?
 
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Old 12-21-11, 11:17 AM
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You could just use a length of #12-2 FMC if this is inside protected from the weather.
 
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Old 12-21-11, 04:05 PM
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I was thinking of UF or the yellow 10ga 3 wire submersible as that is what is all over the well house. Running out the door and will shop for a length of #12-2 FMC. Should the #10 gauge be maintained from box to well house to motor? The well pump motor wires are 10 gauge. The well house is a small house with insulation, steel roof, door, so this should be good.
 
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Old 12-21-11, 05:21 PM
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If you are going to put the pump on a 20a breaker only #12 is required. There are restrictions on running UF without protection. I don't know about pump cable. I'd probably sleeve the UF with ENT if you already have the UF.
 
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Old 12-21-11, 09:55 PM
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I could not find the THWN 10ga individual strand wire at two locations on the plains. Home Depot did not carry THWN 10ga, but THHN house rated wiring. I have one more shot tomorrow at an electrical supply store. The 1 inch Schedule 20 is ready for the trench. One option was 10ga grey UF 4 wire. Can I pull UF through 1 inch Schedule 20 and is this acceptable? It's available locally and 50 dollars cheaper. If this is an option, it may help out tomorrow if I can't locate THWN 10ga. Surprised this is hard to find. Our local hardware has THWN 8ga black but nothing else.
 
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Old 12-22-11, 04:40 AM
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Originally Posted by Pilot Dane View Post
If you get UF carefully unroll the wire. Lay one end on the ground and hold it down. Then walk backwards uncoiling the wire with no twists or kinks. Without kinks or twists you should be able to shove it through each pipe section pretty easily. Make sure to get your wire through ALL your pipe sections before you glue any pipe together.
If you do get UF wire, #10 with three conductors and a ground is about 1/4" x 13/16" if you get two conductor with ground it's about 1/4" x 11/16". So, either will easily fit inside 1" pipe. As mentioned before, lube will make the wire slide easier but it's not needed if you are shoving into 10' sections. If you don't have made for wire lube you can use some liquid dish washing soap.
 

Last edited by pcboss; 12-22-11 at 06:44 PM. Reason: correction
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Old 12-22-11, 07:44 AM
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Most THN wire is dual rated for THWN. Often at the big box store you get someone with limited knowledge. Go back and check what is actually printed on the wire if you just trusted what the employee said. Does it actually say THN/THWN? It would be very unusual for them to have THN wire. Was this on the cut to length large spool? If not that is where you need to look.

The 1 inch Schedule 20 is ready for the trench.
Did you mean schedule 40?
 
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Old 12-22-11, 07:59 AM
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The THN was on a roll on an automated rack. I asked what the difference between the THN and the THWN was: the THWN is heat resistant and the THN is more suited for house wiring. I believe he said the THWN was water resistant, and the THN had to have water tight connections. I spelled it out on paper: THHN. I will go back today and also visit the professional contractor electric supply. Someone told me that a California Home Depot was selling 10 guage TW rated wire for 22 cents a foot. This THN/THHN is 47 cents a foot. The available UF is much cheaper.

If I cannot find a supply of THWN today, I probably will go with the UF as it is local and available. Will follow instructions on unrolling and gluing in 1 inch Schedule 40. It's not Schedule 20 as I had said! Someone said to only glue the male end of the PVC S40 if gluing UF in conduit.
 
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Old 12-22-11, 08:35 AM
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The pro electric supply store only sells THWN in 500 foot rolls. The rep (not an electrician) said he thought THN was OK in exterior conduit.

I may go with the UF, but will try looking some more today.

Just talked to another Home Depot and they said UF (considered a Romex) is can be used in conduit, but the conduit can interfere with heat transfer. 1 inch would give plenty of space, but had not heard anything yet against UF.
 

Last edited by ChollaBob; 12-22-11 at 08:57 AM.
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Old 12-22-11, 09:28 AM
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The maximum capacity of the wire is based on a max of three conductors in a conduit, cable or buried at 86f. So, if you are not pushing the wire to it's max rated capacity it's not an issue. One of the main reasons why UF is not put in a conduit is that it is more difficult to pull than individual conductors. That heavy waterproof cable covering makes it big & stiff.
 
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Old 12-22-11, 10:05 AM
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The rep (not an electrician) said he thought THN was OK in exterior conduit
Guess he must have earned his BS degree at BigBox. That is not true. Have you tried a hardware store or lumber yard? As I said though don't ask at BigBox. Look at the cable for yourself.
 
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Old 12-22-11, 06:03 PM
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Someone told me that a California Home Depot was selling 10 guage TW rated wire for 22 cents a foot. This THN/THHN is 47 cents a foot.
19 to 20 cents a foot is a good price for #10 THHN/THWN wire and 22 cents a foot is ok, but 47 cents a foot is robbery.
 
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Old 12-22-11, 06:07 PM
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If I cannot find a supply of THWN today, I probably will go with the UF as it is local and available.
Look for something like this.

THHN/THWN/TWN75/T90
 
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Old 12-22-11, 06:48 PM
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It will be much easier to pull in the THWN individual conductors vs UF cable. The UF is fairly stiff.

The conductors need to have a W in the rating in order to be used outside in a wet environment. Inside a conduit that is outside is considered wet.
 
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Old 12-22-11, 09:31 PM
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THHN is generally THWN as was pointed out in this thread. On craigslist, there was a shot of a Home Depot 10ga THHN roll and it had the THWN stamp on the picture. Drove through a blizzard to buy the individual strands.

The Depot had rolled my wire with a short length so we had to separate the stands on 85 feet of aisle. The main electric rep said this had not happened in 11 years. It was a circus.

As soon as the weather clears, putting everything together.

That was it: THHN/THWN/TWN75/T90. Thanks!
 
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Old 12-28-11, 08:47 PM
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The 60 feet of 1" Schedule 40 PVC conduit comes up from a 22 inchdeep trench and up a service pole to the main breaker box on the pole. The offset from the pole to the box is 3 inches to a 3/4 inch breakout.

I would like to reduce on the pole the 1" to 3/4" with a threaded coupling and will heat up the pipe to make the correct turn. Is there a minimum height above ground level where I can make the threaded reduction? Is the heat gun bend in the PVC OK?

Thanks!
 
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Old 12-29-11, 05:35 PM
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If I unerstand you correctly, you have a 3/4" knockout and want to reduce the 1" conduit to 3/4" to fit the knockout. You probably could do that, but I would just punch a larger hole for the 1" conduit if it were mine. If you don't have a knockout set you could use a hole saw.
 
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Old 12-30-11, 07:21 AM
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Will go with 1' knockout as it is separated there anyway.

Electrician back from vacation, but dirt road snowbound. Four wires
going into conduit today. Forgot what a shower is like. Thanks!
 
 

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