Running wire to a pole barn.

Reply

  #1  
Old 10-12-01, 03:33 PM
Visiting Guest
Posts: n/a
I read a posting dealing with a similar situation but I did not really understand everything being talked about so I thought I would ask my question and hope for an answer I can follow. Eventually an electrician will be involved in my project but is unavailable at this point for consultation.
I want to run wire from the house out to an existing pole barn and I need to do it soon. I am planning on having a flourescent light fixture and a cabinet there for my tools with two light bulbs inside to help keep the dampness down. ( I live on the coast.) They of course will be on all the time. I will also ocassionally be running some power tools (10 inch table saw, circular saw, drills, maybe a band saw)...only one at a time except when my little Emglo Airmate kicks on. It runs on household current.
The run is about 100 feet including the vertical distance down into and up out of the ground. I was thinking about running that 1" gray electrical conduit two feet (?) under the ground surface. I was also thinking about running 4 #10 solid wires through that conduit from the service box in the house to and through the wall of the pole barn.
I will have the electrician take over at that time. I am wondering if the wire size (and type?) and conduit would be adequate for him to install a small service box in the pole barn with two 20 amp circuits which I think would be enough for my tools and the lights. Someone told me that he could install a double pole switch in the house box to accomodate the smaller service box. Also someone else felt that I should use stranded wire as it would go through the conduit more easily.
What do you think? What type and size of wire would be good to use? What size conduit would be good? Any suggestions on how to feed the wire through? As I said, I will be just be letting the wires stick out near the box in the house and through the wall in the pole barn.
Thanks.
 
Sponsored Links
  #2  
Old 10-12-01, 05:58 PM
hornetd's Avatar
Member
Join Date: Aug 2001
Location: Maryland
Posts: 695
Received 0 Votes on 0 Posts
Do you need conduit?

If it were my home I would run 1&1/2" conduit for a couple of reasons. The first is to allow for future changes in the way the barn is used. The second is to make it easier to pull the wires in. If you do not have any likelihood of needing any additional power in the future then the 1" would be fine but it would be easier and cheaper to run type UF cable. UF can be buried without a raceway and on residential properties the depth of bury, for either wiring method, can be 1 foot if the circuit is GFI protected and the OCPD (i.e. the breaker or fuse) is thirty amps or lower. You will need to install a grounding electrode system at the barn if you run the circuit as two or more branch circuits or as a feeder to a panel containing breakers. If you run only one branch circuit you can forget about additional grounding at the barn.
--
Tom
 
  #3  
Old 10-13-01, 08:38 AM
Visiting Guest
Posts: n/a
Thanks Tom,
The reason I was wanting to run conduit is that we are two blocks away from the Pacific Ocean. Our annual average rainfall is 90-95 inches and since we are about two feet above sea level, our water table can be very high. Any thoughts?
Also, since I would need a ground at the barn, do I need to make a branch or something in the conduit before it goes through the barn wall?
Yooper
 
  #4  
Old 10-13-01, 09:54 AM
hornetd's Avatar
Member
Join Date: Aug 2001
Location: Maryland
Posts: 695
Received 0 Votes on 0 Posts
Originally posted by seatrout
Thanks Tom,
The reason I was wanting to run conduit is that we are two blocks away from the Pacific Ocean. Our annual average rainfall is 90-95 inches and since we are about two feet above sea level, our water table can be very high. Any thoughts?
Also, since I would need a ground at the barn, do I need to make a branch or something in the conduit before it goes through the barn wall?
Yooper
Most underground conduits end up filled with rain or ground water anyway. This is why all conductors intended for use in the ground need to be listed for wet locations. Once again the two best reasons to run conduit are to protect the conductors from physical damage and to make changing the wiring later much easier. If no expanded use of electricity is planned or even remotely anticipated you can save money and effort by using type UF cable. Uf cable is just as resistive to moisture as THWN pulled in conduit. In most UF cables the individual conductors are listed as THWN. Type THWN conductors are Thermo plastic, High temperature (75C), Wet locations, Nylon covered.

As for branching the conduit, it is unnecessary. Your pole barn; or any other structure for that matter; must have a building disconnecting means. This can take several different forms but in your case the simple one is to run the conduit or cable into a box immediately inside the building at a point near the place the wires enter. The box should be a deep four inch square box. In your location plastic is preferred. In a raised cover mounted to the box you will install a double pole switch through which both ungrounded conductors will pass. This switch will be your building disconnecting means. In the same box you will splice all the Equipment Grounding Conductors (or EGCs) together with two short leads. You will connect one short lead to the Grounding Electrode Conductor (GEC) using a split bolt connector. The other short lead will terminate to the grounding screw on the strap of the switch. The GEC need be no larger than #12 AWG but any GEC smaller than #6 requires physical protection and #6 requires physical protection were exposed to physical damage.

"Installation.
Grounding conductors shall be installed as specified in (a), (b), and (c) below.
(a) Grounding Electrode Conductor. A grounding electrode conductor or its enclosure shall be securely fastened to the surface on which it is carried. A No. 4, copper or aluminum, or larger conductor shall be protected if exposed to severe physical damage. A No. 6 grounding conductor that is free from exposure to physical damage shall be permitted to be run along the surface of the building construction without metal covering or protection where it is securely fastened to the construction; otherwise, it shall be in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or cable armor. Grounding conductors smaller than No. 6 shall be in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or cable armor."

For that reason I always use #4 AWG for grounding electrode conductors were the service or feeder is 200 amperes or smaller. The EGC is connected to the spliced EGCs with a split bolt connector inside the building disconnecting means enclosure. It runs back out of the building through the same hole in the wall were the cable or conduit entered or through a separate hole if the fit around the conduit is kept small enough to insure a snug fit. It runs back down into the trench and connects to the first ground rod by running through the acorn clamp on that rod and on to the acorn clamp on the second rod. The rods are driven into the bottom of the trench to improve there performance by deeper burial and to protect them and the GEC from severe physical damage. Using the feeder trench avoids digging a second trench for the GEC.
--
Tom
 
  #5  
Old 10-13-01, 01:36 PM
hornetd's Avatar
Member
Join Date: Aug 2001
Location: Maryland
Posts: 695
Received 0 Votes on 0 Posts
Optional Grounding Opportunity.

You might want to consider doing your grounding for the pole barn in the way I have described it to another poster at,
http://forum.doityourself.com/showth...threadid=70615. The method I describe there is extra work and it is in no way required but it will greatly improve the safety of the entire installation by improving it's grounding.
--
Tom
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: