What wire for 100 amp sub panel 180 feet away.

[Gone_fishing]

We have a 40 x 60 shop I am wanting to put a 100 amp sub panel in. Right now I am just trying to price up everything I would need so I can decide if it’s financially feasible this year and I am hung up on the wire. We have 200 amp service at the house and from the box which is located outside the house to the shop is 180 feet. I used the calculator on Southwire and it looks like 2/0 is what I need? So is that 2/0 2/0 2/0 0-1? Is direct burial the way to go? And is there a preferred place to get wire? Any guidance is very appreciated.

 

[u2slow]

Check the size of the lugs in the 100A panel. Probably tops out at #1/0 or #2/0.

Direct burial aluminum cable is what we commonly do here.

 

[Gone_fishing]

Check the size of the lugs in the 100A panel. Probably tops out at #1/0 or #2/0.

Direct burial aluminum cable is what we commonly do here.

I don't have the 100 amp box yet but will check into that. As far as wire is this what I would need?

 

[pattenp]

You need MHF, not URD. URD is strictly outside use only and is not to enter the structure. I assume on the shop end the wire will be entering the structure to the panel. You could terminate the URD outside and switch to SER going into the shop.

 

[Gone_fishing]

You need MHF, not URD. URD is strictly outside use only and is not to enter the structure. I assume on the shop end the wire will be entering the structure to the panel. You could terminate the URD outside and switch to SER going into the shop.

Thanks for the info. Yes it will enter the shop because I want the breaker box on the inside. So I should price up 2/0 2/0 2/0 1/0 MHF mobile home feeder?

 

[pattenp]

You'll most likely find the MHF in 2/0-2/0-1-4.
You do know the URD or MHF needs to be in conduit where above ground?

 

[mike93lx]

Some URD is dual rated, but mhf is a safe bet as it's all allowable indoors, in conduit. 2/0-2/0-1-4 is what I would do.

Try Wireandcableyourway.com

 

[Gone_fishing]

Some URD is dual rated, but mhf is a safe bet as it's all allowable indoors, in conduit. 2/0-2/0-1-4 is what I would do.

Try Wireandcableyourway.com

Got it, thanks I will check them out

 

[rwilly]

I used 2224 MHF in 1 1/2” conduit.
Aluminum.
I ordered 260’ and the price was $1200.00.
It passed inspection.

I got it from Nassau National Cable.

 

[wyliesdiesels]

260' is a little long for #2 al @ 90a... did you breaker it lower?

 

[mm08822]

260' is a little long for #2 al @ 90a... did you breaker it lower?

I hope so. Depends what his starting voltage is at house.
3% VD @ 50Amps.
5% VD @ 70A.
6% VD @ 90A This would start to be trouble if there is only 230v at house.

 

[fireblue]

I have ordered from Nassau and “wire and cable your way.” Way better pricing than electric supply house. However, I think you should go in your local electric supply house and ask them what wire you’d use for a detached building subpanel run underground for 100a service run 180’. Most places direct burial is normal, but there are some places with the type of rocks/soil that use conduit more often. Nice to go in and get to ask what’s normal locally. Ask the local inspector too. Feeder sizing is a bit of witchcraft especially when figuring out the cheapest route to take with whatever conduit/wire type might have a current shortage or price-hike, as you can see if you google “feeder sizing for adu / garage / shop” and look at electrician forums. With electricians talking about MHF with reduced neutrals or full-sized/triplex/SER/URD/URD double rated/URD triple rated/USE2/conduit/direct burial/overhead, etc. Also occasionally it is cheaper and easier to have a second meter if your local electric company has a low minimum billing amount and includes so many feet of new service wire burial for free; you might pay more over a long period of time with the monthly base rate, but you don’t have to come up with $5k for wire/conduit/excavation/labor to run a subpanel from your existing service.

 

[mike93lx]

There is no witchcraft. Just people that don't understand the rules.

 

[wyliesdiesels]

I have ordered from Nassau and “wire and cable your way.” Way better pricing than electric supply house. However, I think you should go in your local electric supply house and ask them what wire you’d use for a detached building subpanel run underground for 100a service run 180’. Most places direct burial is normal, but there are some places with the type of rocks/soil that use conduit more often. Nice to go in and get to ask what’s normal locally. Ask the local inspector too. Feeder sizing is a bit of witchcraft especially when figuring out the cheapest route to take with whatever conduit/wire type might have a current shortage or price-hike, as you can see if you google “feeder sizing for adu / garage / shop” and look at electrician forums. With electricians talking about MHF with reduced neutrals or full-sized/triplex/SER/URD/URD double rated/URD triple rated/USE2/conduit/direct burial/overhead, etc. Also occasionally it is cheaper and easier to have a second meter if your local electric company has a low minimum billing amount and includes so many feet of new service wire burial for free; you might pay more over a long period of time with the monthly base rate, but you don’t have to come up with $5k for wire/conduit/excavation/labor to run a subpanel from your existing service.

Asking a local supply house counter rep is a bad idea. They arent electricians

Also SER cannot go underground

 

[mm08822]

I have ordered from Nassau and “wire and cable your way.” Way better pricing than electric supply house. However, I think you should go in your local electric supply house and ask them what wire you’d use for a detached building subpanel run underground for 100a service run 180’. Most places direct burial is normal, but there are some places with the type of rocks/soil that use conduit more often. Nice to go in and get to ask what’s normal locally. Ask the local inspector too. Feeder sizing is a bit of witchcraft especially when figuring out the cheapest route to take with whatever conduit/wire type might have a current shortage or price-hike, as you can see if you google “feeder sizing for adu / garage / shop” and look at electrician forums. With electricians talking about MHF with reduced neutrals or full-sized/triplex/SER/URD/URD double rated/URD triple rated/USE2/conduit/direct burial/overhead, etc. Also occasionally it is cheaper and easier to have a second meter if your local electric company has a low minimum billing amount and includes so many feet of new service wire burial for free; you might pay more over a long period of time with the monthly base rate, but you don’t have to come up with $5k for wire/conduit/excavation/labor to run a subpanel from your existing service.

The only witchcraft in feeder sizing is trying to estimate the future loads. Initial loads, distance, material of construction, all provide a solid answer. I'd rather be oversized to start than have to re-do the feeder or limit the way I work.

The cheapest route to take can be very short sighted. May wind up replacing feeder if not placed in conduit or in a bed of select material. It only takes 1 rock. Soil conditions can vary greatly in a short distance.

No matter which wiring method/material combination is chosen due to availability and pricing, long term service integrity should be the priority and adjusted to site conditions.

 

[heierlu]

I'd check your local supply house. They ended up having the best price I could find anywhere and even had it in stock. Most of the supply houses here apparently refer to it as URD, but turns out it's actually USE-2 and RHH/RHW rated on the jacket. I've found that even supply houses have no idea what the rating are or what they mean. So it's worth asking them to take a look at their URD wire.

 

[Innovate1]

If you do continuous conduit you could also use XHHW. Gives you more options on sizes. You need to check with the local AHJ for what is allowed. Some places don't allow reduced neutral for example.

 

[rd65]

I used 2/0 XHHW-2 aluminum wire in conduit. My run is about 210', 200 amp service at house, 100 amp in shop. I messed up on my ground wire, should have been copper but the store gave me aluminum, inspector was ok with it as I had the 2 ground rods at the shop that they wanted.

 

[mike93lx]

I used 2/0 XHHW-2 aluminum wire in conduit. My run is about 210', 200 amp service at house, 100 amp in shop. I messed up on my ground wire, should have been copper but the store gave me aluminum, inspector was ok with it as I had the 2 ground rods at the shop that they wanted.

The ground wire between panels is just fine as aluminum.

Ground rods serve a different purpose, too

 

[theoldwizard1]

You'll most likely find the MHF in 2/0-2/0-1-4.

OP, you do know that there is no reason to match the breaker in your sub with the breaker in your main panel, don't you ? Drop down to a 90A or even a 60A breaker in you main panel and you will save a ton on cable !

You do know the URD or MHF needs to be in conduit where above ground?

Or put a J-box were it transition from below ground to above (on the side of the building) and then you can transition to NM-B. Make sure to use splices that are rated for both Cu an Al.

 

[mm08822]

Or put a J-box were it transition from below ground to above (on the side of the building) and then you can transition to NM-B. Make sure to use splices that are rated for both Cu an Al.

You would still need a conduit to enter the jbox from the ground.

Bigger question.....why would anyone want to add j-boxes, splicing hardware and extra labor when conduit could be run directly into the back of the panel with an LB and eliminate all splices? And that would apply at both ends....so x2!

 

[theoldwizard1]

You would still need a conduit to enter the jbox from the ground.

Bigger question.....why would anyone want to add j-boxes, splicing hardware and extra labor when conduit could be run directly into the back of the panel with an LB and eliminate all splices? And that would apply at both ends....so x2!

It depends where the panel is mounted.

 

[mike93lx]

You would still need a conduit to enter the jbox from the ground.

Bigger question.....why would anyone want to add j-boxes, splicing hardware and extra labor when conduit could be run directly into the back of the panel with an LB and eliminate all splices? And that would apply at both ends....so x2!

My panels aren't accessible like that at all. I have to go into my crawl and then run over to them.

Also, having an LB as high as it would need to be to get into most panels would be quite unsightly in many apllications

 

[mm08822]

My panels aren't accessible like that at all. I have to go into my crawl and then run over to them.

Also, having an LB as high as it would need to be to get into most panels would be quite unsightly in many apllications

It's all about planning the conduit run first. My goal would be to eliminate splices whenever possible. Don't build in extra cost without first considering alternate routes/locations. I would rather use an LB through the sill plate (your crawl space example) than look a large jbox big enough for splices. Paint makes for good camouflage for a simple conduit.

 

[mike93lx]

It's all about planning the conduit run first. My goal would be to eliminate splices whenever possible. Don't build in extra cost without first considering alternate routes/locations. I would rather use an LB through the sill plate (your crawl space example) than look a large jbox big enough for splices. Paint makes for good camouflage for a simple conduit.

No argument against avoiding a j box. I'm just saying that using an lb into a panel isn't always an option

 

[Norcal]

I used 2/0 XHHW-2 aluminum wire in conduit. My run is about 210', 200 amp service at house, 100 amp in shop. I messed up on my ground wire, should have been copper but the store gave me aluminum, inspector was ok with it as I had the 2 ground rods at the shop that they wanted.

A AL grounding conductor is fine as part of a feeder, aluminum to ground rods would be a big no no.

 

[rd65]

A AL grounding conductor is fine as part of a feeder, aluminum to ground rods would be a big no no.

The issue wasn't that the ground from main panel being aluminum but that it was sized as though it was copper, so too small. The wire from sub panel to rods is copper.