Electric in to pole barn question

[hr3]

Thanks. I am running 4 wires out there. You guys do argue a lot ... it is entertaining and informative ...

We don't argue much,, But we do agree to disagree alot,,,

 

[debo1683]

Thanks again guys. I thought about it and looked at stuff again last night and decided to put a hole in the concrete. Your help is more than appreciated ...

 

[ENG18LT]

Not sure if you have done it yet, if you haven't...... The hole in the floor only needs to be big enough to accommodate your conduit, as opposed to a larger chunk. Then when you did your trench outside just dig under the slab enough to get the conduit in and up. Once that is done backfill it with a small aggregate that will support the slab. Key is to disturb as little substrate as necessary to get the job done. Also you may want to consider filling the gap between the conduit and existing slab with "hydraulic cement", this will provide a better seal then standard concrete.

 

[billybobjimmyjoejack]

If the edge of your slab is not to thick and you have a large enough bit for your roto-hammer, you could drill straight down from the inside and then tunnel under the slab from the outside.
Drop the conduit from the top side into the trench, then add a 90 on the outside for you run inside the trench.
You can add a ground rod by just drilling a hole in the slab larger than the rod itself. No patching of concrete would be needed.
If you are concerned about water coming in around these holes I would suggest you drill your holes about 1/4" larger all the way around (1/2" dia. larger) and install your penetrations then use a urethane based caulking to seal the opening.
This will make the opening water tight and provide some flexibility between the penetrations and the concrete slab.

 

[Darrenone]

If you are running 4 wires from your house panel then why do you need a ground rod? You are grounded through your house service.

 

[gengine]

For 100' and 100amps, I would guess you are using 4-0 wire. If you are running conduit from the house to the barn, every turn you put in there makes it significantly tougher to pull your wire, so you have to be thinking about this. Our local power company won't do over three turns, wether 90 or 45 degrees. Check with you local codes on what I've said, don't take my word for it. That is what is allowed here. Just did kinda the same thing a couple weeks ago.

 

[Darrenone]

You should be able to use direct burial cable and just sleeve it through the conduit when entering the barn.

 

[powerpace]

Code for my metal sheathed pole barn on concrete slab required: (1) 2 ground rods outside the drip line ten feet apart with the clamps on the rods showing. (2) Ufer ground to the concrete slab rebars.

I would not break any concrete to put conduit in. Once you break the concrete it can cause all sorts of problems. Go with trenching around the concrete slab. Use gravel at the ground exit below the panel.

 

[grsthegreat]

for your information on the previous 2 posts.

1. NEC requires 1 additional ground rod for 100 amp subpanel in separate building (2 rods for 200 amps). It doesnt matter that 4 wires were run. the ground rod is still required.

2. I usually lay out the wires out along side the trench first THEN slip the conduit onto the wires 10 - 20 feet at a time. This is done prior to dropping conduit into tranch. This way i can run 100's of feet of wire and conduit myself and never have to actually pull the wires. It works slick and saves alot of labor costs. If the conduits HAVE to be installed empty, then i always upsize the conduits otherwise youll be hating yourselves later on. (and i have the use of pullers and pulleys and it still sucks to pull thru tight conduits.)

 

[powerpace]

The best advise will come from whomever is going to inspect the installation. It won't hurt to ask.