Running 100amp sub to new building

[dsp1]

It's finally time to run power to the new shop. We had to get the 200 amp box and service entrance wire on the house replaced due to water intrusion so now everything is encased in conduit and brand new. So, here is the plan:

115' run (approx. 55% underground/45% dank basement of 1/0 aluminum xhhw-2 cable encased in conduit the whole way- I really don't like splices/junction boxes
100 amp breaker on 200 amp house panel - according to electricians the house panel can handle that no problem
3- 1/0 conductors for hot and neutral 6 awg copper for panel to panel ground- all the electricians around here I've talked to run the same size conductors for hot and neutral.
2 ground rods outside the building
100 amp 30 space panel
2" conduit

It's crazy, but it's half the cost to buy 1/0 cable online compared to what local suppliers want for 2 awg near me.
Is there anything I'm missing or that you guys would recommend? Has anybody found a really clean way for drilling/cutting large holes in metal pole barn siding?

What I could really use help/advice with is the conduit. What is the best/ easiest way to pull the cable? Which end would you pull from, running to the panels, etc. I've run emt and legrand metal conduit in garages before but this is a bit bigger in scale so any experienced advice before I get started will be appreciated.

 

[dcg9381]

90A is the typical GJ recommendation as you can use aluminum MHF and that's the value for amps per dollar. And yes, ordering cable can save you money.

I use a typical bi-metal hole saw to drill holes in R panel. No big deal.

You're pulling cable 115'. If you use 2-2-2-4 it'll go through 2" conduit no problem (I assume it's ok at this distance, didn't check). The trick is to push and pull at the same time, using wire lube. You install the conduit, vacuum (shop vac) a pull string with a little plastic bag on the end, then you use that to pull the wire... Have someone on the other end doing the feed. I try to feed the straight section and then slide the elbows over at both ends later.

 

[Innovate1]

A lot of people here get wire from wireandcableyourway.com. That's what I did. I didn't run voltage drop but you can probably go with #1 rather than 1/0 for that distance at 100A and use 1.5" conduit - it's much bigger than needed so should be an easy pull. Use long sweeps for the bends whatever size you use.

 

[Innovate1]

90A is the typical GJ recommendation as you can use aluminum MHF and that's the value for amps per dollar. And yes, ordering cable can save you money.

I use a typical bi-metal hole saw to drill holes in R panel. No big deal.

You're pulling cable 115'. If you use 2-2-2-4 it'll go through 2" conduit no problem (I assume it's ok at this distance, didn't check). The trick is to push and pull at the same time, using wire lube. You install the conduit, vacuum (shop vac) a pull string with a little plastic bag on the end, then you use that to pull the wire... Have someone on the other end doing the feed. I try to feed the straight section and then slide the elbows over at both ends later.

You aren't supposed to glue after the wire is in place. The glue can attack the wire insulation.

 

[dcg9381]

You aren't supposed to glue after the wire is in place. The glue can attack the wire insulation.

Thanks.

 

[Innovate1]

Wireandcableyourway.com can supply the wire on 4 individual spools which makes things much easier. Other places could probably do the same thing. I put a piece of pipe through all the spools and suspended them above one end for a nearly straight shot into the conduit. Then I put a tripod out of 2x4s over the other end with a pulley at the top - it's much easier to pull down then to lift up, especially with the end of the conduit at several feet off the ground. Have a helper at the other end. One feeds the wire into the conduit with some lube. The other one pulls. If you have everything set up well it should be a quick and not too difficult job.

 

[reader2580]

You're pulling cable 115'. If you use 2-2-2-4 it'll go through 2" conduit no problem (I assume it's ok at this distance, didn't check). The trick is to push and pull at the same time, using wire lube. You install the conduit, vacuum (shop vac) a pull string with a little plastic bag on the end, then you use that to pull the wire... Have someone on the other end doing the feed. I try to feed the straight section and then slide the elbows over at both ends later.

What I did for my 75 foot conduit was to use my shop vac to pull through mason line. I then attached some heavier line to the mason line and used the heavier line to pull the copper through.

I used 2" conduit to have plenty of room, but I did back in 2017 when 2" conduit was not sky high in price.

 

[dsp1]

Thanks for the advice, I appreciate it. I had seen other posts about the glue eating through the insulation so I was hoping to hear how you guys pulled it through already set up conduit. Is it easier to pull all the wires together at the same time or do them individually? Depending on what calculator/table I looked at it varied between 1 awg and 1/0. I am planning on an addition and some larger equipment down the road so I figured the 1/0 wouldn't hurt. You're not wrong though, I have been giving the 1 awg and 1 1/2" conduit some serious thought. The difference in wire isn't much but the difference in conduit certainly is.

 

[reader2580]

My experience is pulling everything at once is easier. If you do one wire at a time my experience is the pull rope/tape can get wrapped around the other wires already installed.

 

[mike93lx]

Absolutely all together.

 

[Innovate1]

Do them all at once. I stripped about 8" off all the wires, split the strands about equally, and folded half over one way to make an eye and half over the other way around the pull rope. Do that with all of them keeping the bunch small. Trim some strands if you need to to keep it small. Then tape the tails of the strands well. For bending the sweeps I used steam from a tea kettle through a larger tube with the PVC inside for a couple minutes. Makes the PVC very flexible. Grab it with some gloves (it's hot!) and bend it on the floor and hold for a minute or two to cool. Others will say use a torch or heat gun but I didn't have good results on larger conduit that way.

 

[mm08822]

For bending pvc conduit regardless of the heating method, I put chalk lines down on the floor to make sure I bend to the correct dimensions and parallel, etc. Even with gloves, large conduit can get hot, and they help to quickly get it set. Even helps when cooling off the bend with water to make sure the bend is still as planned.

If you think you will ever pull additional conductors in a conduit, always pull a drag line with the first set of conductors. This eliminates a significant amount of interlacing new conductors within the original conductors.

 

[dsp1]

I got the cable ordered and am going to pick up the ground rods and ground wire tomorrow. When I was there the other day they had bare 6 awg stranded and solid copper ground wire. Is it just a matter of personal preference? I prefer stranded wire since it is a lot easier to deal with unless the solid copper is drastically better.

 

[Max]

Probably obvious, but if you want to put in wires for Ethernet, alarms, etc now is the time to do it. I’m 98% certain you can run fiber in the same conduit, but any low voltage copper wires will need a separate conduit.

 

[MerlinsBeard]

I got the cable ordered and am going to pick up the ground rods and ground wire tomorrow. When I was there the other day they had bare 6 awg stranded and solid copper ground wire. Is it just a matter of personal preference? I prefer stranded wire since it is a lot easier to deal with unless the solid copper is drastically better.

For ground wire, solid copper should be more robust to the elements and rodent activity. AWG 6 is typical, though you can go higher but most of the time you do the minimum since wrangling the ground wire to a panel can be a bear. I prefer getting copper plated ground rods as the corrosion resistance is much better for a nominal cost increase.

 

[alfredeneuman]

I didn't run voltage drop but you can probably go with #1 rather than 1/0 for that distance at 100A

I did ... and you can only load it up to 55 Amps with out exceeding the suggested voltage drop of 3% maximum,

 

[Innovate1]

I did ... and you can only load it up to 55 Amps with out exceeding the suggested voltage drop of 3% maximum,

I just ran the numbers: 115 feet of #1 AL at 100A for 240V circuit gives me 2.32% with Southwires calculator. I could be wrong but it seems to me you have some error in your figures. 55A is a very low value for that size wire.

 

[alfredeneuman]

seems to me you have some error in your figures.

You're right! I used this one. https://www.calculator.net/voltage-drop-calculator.html and came up with 2.77% VD. I was reading "the total voltage dropped" figure instead of the %.