wiring to a sub-panel

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  #1  
Old 09-12-02, 07:15 PM
J
jrde2000
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wiring to a sub-panel

I am in the process of running new electricity to a camp house. The main panel is 125amps and is located on the meter pole and has a grounding rod. Right now there is one circuit for a well and one for outside lights.

My plan is to use a 125 circuit in the main, run ((3) - 2 hot , 1 neutral) #1 THHN copper in conduit 17ft. up the pole. From there splice to (2) #1 THHN copper and an exisiting bare neutral wire and run over head to the house which is less than 100ft. From the eave of the house splice to ((3) - 2 hot , 1 neutral) #1 THHN copper that goes inside the house to a 125amp subpanel. I was not planning on a main breaker for this panel, but I will have more than 6 circuits. I have the neutral bars seperated and one is wired to a grounding rod just outside the house.

I want to make sure this is correct. Any comments would be helpful.

Thanks.
 
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  #2  
Old 09-12-02, 07:57 PM
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Gary Tait
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I'd probably think about installing a panel with
a main breaker.

I'd also run a triplex rated for overhead use.
 
  #3  
Old 09-13-02, 05:59 AM
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texsparky
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Use quadraplex for the overhead run so that you have an insulated neutral.
 
  #4  
Old 09-14-02, 10:33 AM
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Wgoodrich
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This installation has a few questions that arise in my thoughts.

First the wires coming from the load side or your main breaker installed in that service rated panel on the pole must not be in the same conduit as the service conductors serving that main service rated panel. Line and load is not allowed in the same conduit concerning a service.

The THHN that is spoken of must have written on the side of the wire SUNLIGHT RESISTANT. Most THHN while dual rated as also being THWN allowing for a wet location is not sunlight resistant allowed to be used as overhead wiring.

The overhead wiring as discribed in this post must be supported by a messenger cable that has an inner core wire of steel to be used as a messanger cable. Just a bare wire does not meet the definition of a messenger cable. Make sure you have a steel wire as the inner core of that overhead bare wire that is supporting that overhead cable.

The panelboard in the second building being fed by a common service is required to have a main disconnect or meet the maximum number of breakers of less than 6 sweeps of hte hand. See article 225.31 and 225.32 that would apply to this installation.

A four wire feeder is not required in this installation if there is no non-current carrying metatallic parts connecting between the two buildings.

If a three wire feeder is installed to serve this commons service serving two structures then a grounidng electrode system must be installed at the second building per 250.66 and 250.50. and 250.32. If the three wire feeder without an equipment grounding conductor is installed then the neutral bar and grounding bar must be married as one entity including the metal case of the panelboard in that second strucutre.

If there is a noncurrent carrying metallic path present between the two buildings then an equipment grounding conductor must be ran as part of the feeder between buildings as one four wire cable and the main disconnect is still required at nearest point of entrance to that second building and the grounding electrode system is still required to be installed at that second building, but the neutrals and neutral bar must be isolated from the grounding and grouniding bar and the metal case of the panelboard.

The wire sizes seem fine

Hope this helps

Wg
 
  #5  
Old 09-14-02, 08:20 PM
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jrde2000
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Thanks Guys for the input.

Iíve had a hard time locating the triplex wire and the ability to buy it by the foot, so I have changed plans.

Now I am going to bury the cable and run (3) #1 copper THHN wires in 1 1/4 pvc conduit. That will be the only thing connecting the house and the pole.

I want to double check this. According to Wg, I will put the bar back in the subpanel connecting the ground and the neutral so it is one. The subpanel is grounded to its own grounding bar.

Is this the best way to do it, or would I be better off going ahead and running the fourth wire now. I guess if I ran four wires I would use a 1 1/2 pvc conduit.

Thanks again for you help.
 
  #6  
Old 09-15-02, 12:55 PM
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Wgoodrich
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If you ran 3 - 1 awg copper conductors THWN and a bare grounding conductor in a sch 80 PVC as required above ground exposed to physical damage then you will need 1 1/2" PVC conduit.

If you install three wires without an equipment grounding conductor then you must install the grounding electrode in the ground and use that as your grounding electrode system if you have no metal water pipe in direct contact with the earth for at least 10' and 2' deep. This panel in you home will need the neutral and grounding married as one entity.

If you install the equipment grounding conductor with the feeder to that home from the pole service then you will need to separate the neutral bar and grounidng bar in that house panel. You will still have to install the ground rod either way.

AS to whether a four wire feeder or three wire feeder is best is a one on one decision only left to the owner as long as there is no noncurrent carrying metallic path between the two structures.

Hope this helps

Wg
 
  #7  
Old 09-16-02, 07:00 AM
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Originally posted by jrde2000
Thanks Guys for the input.

I've had a hard time locating the triplex wire and the ability to buy it by the foot, so I have changed plans.

Now I am going to bury the cable and run (3) #1 copper THHN wires in 1 1/4 pvc conduit. That will be the only thing connecting the house and the pole.

I want to double check this. According to Wg, I will put the bar back in the sub panel connecting the ground and the neutral so it is one. The sub panel is grounded to its own grounding bar.

Is this the best way to do it, or would I be better off going ahead and running the fourth wire now. I guess if I ran four wires I would use a 1 1/2 pvc conduit.

Thanks again for you help.
jrde2000
Do yourself a favor and run four wires to the building. Buy type UF individual conductors in number one AWG Cu. Run the fourth wire as bare number two AWG Cu. The only place you have to use covered or insulated wire for the Equipment Grounding Conductor (EGC) is if there is livestock present or if the soil is corrosive to copper. The bare EGC will then function as an auxiliary grounding electrode for it's entire length. That will work a lot better if your trench is deeper. If your having it dug by machinery have them make it three feet deep. You still have to have a grounding electrode system at the building but the rod at the pole and whatever you install for an electrode at the building will behave as one electrode if you run the larger conductor.

The UF and bare copper EGC will require the protecction of conduit were it comes up out of the trench at each end.

If your telephone does or will come in on the same poles then consider installing a conduit now for communications wiring. This can be installed in the same trench by backfilling the first foot and then running the comm. conduit.
--
Tom
 
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