[Kernel]

Hello and Happy New Year!

I want to wire a 100 Amp sub panel in my garage to supply power to some machines for wood and metal working. A small phase converter is planned after this sub panel is done. This garage is separated from the main panel by a concrete court yard (illustration attached below). The total length of the wire run is 80 feet +/- 2 feet. The subpanel will be placed inside.

Per Southwire's calculator, I need #1/0 aluminum to minimize voltage drop. Please correct me, but I would need 1/0-1/0-1/0-4 wire, right? I think SER is no longer allowed for direct burial per the latest NEC. I can't find and don't know where to find a three-conductor + ground wire for direct burial (or in conduit), outdoor application. I plan to put it in a conduit regardless.

Thank you for the help in advance!

 

[Arrow3030]

1/0 AL is definitely large enough. #4 AL for an grounding conductor is also large enough. If you're using conduit I don't recommend a cable but rather single conductor.
You seem to be over sizing the conductors BTW.

 

[Smokeshow]

If you want to use conduit, I would recommend pulling 3 #1 and a #4 XHHW in through an 1-1/2" PVC conduit. I might even consider 2" if you're going to have 4 90's like you show in the picture.

 

[Kernel]

I'm surprised by how much the difference in cost of aluminum vs copper. At Wire and Cable To Go website, 1/0-1/0-1/0-2 Nortre Dame URD aluminum cable is $1.72/ft; at 90 feet, that's $154.80. Contrast that to #1 XHHW copper at $1.58/ft; at 90 feet x 3 conductors, that's $426.6. Almost 3X the cost and not accounting for a bare copper #4 wire for ground!

The general consensus I glean from reading the discussions is for copper, a better conductor with less expansion, corrosion, oxidation issues vs. aluminum.

What do you think?

 

[Know A Little]

The general consensus I glean from reading the discussions is for copper, a better conductor with less expansion, corrosion, oxidation issues vs. aluminum.

What do you think?

There is NO ISSUE with aluminum when properly installed. The utility companies use it extensively, your house is more than likely fed with Aluminum.

 

[Plumbvoltage]

I have 2 - 200 amp services on my property and both are fed with aluminum. Both have a 100 amp subpanel fed with aluminum also. No issues with either one.

 

[Smokeshow]

I'm surprised by how much the difference in cost of aluminum vs copper. At Wire and Cable To Go website, 1/0-1/0-1/0-2 Nortre Dame URD aluminum cable is $1.72/ft; at 90 feet, that's $154.80. Contrast that to #1 XHHW copper at $1.58/ft; at 90 feet x 3 conductors, that's $426.6. Almost 3X the cost and not accounting for a bare copper #4 wire for ground!

The general consensus I glean from reading the discussions is for copper, a better conductor with less expansion, corrosion, oxidation issues vs. aluminum.

What do you think?

Sorry, I meant XHHW Aluminum #1. Although Aluminum THWN is just as good too. I just find XHHW pulls much nicer in the dead of winter up here.

 

[Kernel]

Thank you everyone. I plan to use 1 1/4 pvc for the copper OR 1 1/2 for the aluminum. Because of the 4 90-degree turns, I plan to put the wires into the conduit sections, dry fit all of them, and then glue up with the wires already inside.

I did this once with a run of ~150' of Romex 12-2 (+ground) for a backyard GCFI circuit/outlet. I worked out well.

I am leaning copper on this job, though more expensive. Smaller wires, less obtrusive conduit, etc. Maybe I am crazy. No?

 

[rjniles]

Thank you everyone. I plan to use 1 1/4 pvc for the copper OR 1 1/2 for the aluminum. Because of the 4 90-degree turns, I plan to put the wires into the conduit sections, dry fit all of them, and then glue up with the wires already inside.

I did this once with a run of ~150' of Romex 12-2 (+ground) for a backyard GCFI circuit/outlet. I worked out well.

I am leaning copper on this job, though more expensive. Smaller wires, less obtrusive conduit, etc. Maybe I am crazy. No?

Assembling the conduit with the wire in place is a code violation. Assemble it all and pull in the wire. Reason, glue can eat the insulation.

 

[Oso954]

Thank you everyone. I plan to use 1 1/4 pvc for the copper OR 1 1/2 for the aluminum.

You are generating a lot of extra work for yourself. Use 2 inch with long radius 90's, not the short radius ones found at the big boxes. It will cost a bit more, but save you a lot of sweat and trouble.

 

[Kernel]

Assembling the conduit with the wire in place is a code violation. Assemble it all and pull in the wire. Reason, glue can eat the insulation.

Ah! I've wondered about this for a while. Thanks for letting me know. There goes my plan to make it a bit easier.

What do you recommend to use as a pull rope? I think metal fish tape isn't prefered by some of the electricians on this board.

You are generating a lot of extra work for yourself. Use 2 inch with long radius 90's, not the short radius ones found at the big boxes. It will cost a bit more, but save you a lot of sweat and trouble.

Oso954, I presume you are referring to the "long radius" 90-degree elbows like this one at the local orange box? They are long and large.

 

[rjniles]

http://d2pbmlo3fglvvr.cloudfront.net/product/large/Z11N0wfo5oy.JPG

 

[Know A Little]

Ah! I've wondered about this for a while. Thanks for letting me know. There goes my plan to make it a bit easier.

It is not easier, it would be a royal PIA

What do you recommend to use as a pull rope? I think metal fish tape isn't prefered by some of the electricians on this board.

Fish tape to pull in a rope, plenty of wire ease and properly laid out conductors that are not twisted.


2" PVC should be a snap.

 

[Plumbvoltage]

What do you recommend to use as a pull rope? I think metal fish tape isn't prefered by some of the electricians on this board.

Put it together and then get yourself a ziploc baggy and a some heavy fishing line. Stuff the ziploc in the end with the line attached and use a shop vac to suck the baggy through to the other end. Hook a heavier line to the fish line and pull that through. Now you have your pull rope for the wire. Worked on mine great and it was about 75ft.

 

[Know A Little]

And remember it is not about pulling the conductors it is about a coordinated effort of feeding the conductors and pulling, and cannot stress enough to lay the conductors out and have the person feeding the wire keep them straight.

Two people can do this but 4 would make the job easy

 

[carmusic]

too bad teck or acwu is not popular in US, it would be a lot easier, that armored cable can directly buried

 

[rjniles]

too bad teck or acwu is not popular in US, it would be a lot easier, that armored cable can directly buried

A lot of us don't like direct bury. With conduit, if you have a problem you can replace it without a shovel. Or if you decide you need more capacity, pull in bigger.

 

[Kernel]

I went to a local electrical supply house to see what is available. I were told by one of the staff members that THHN is OK for underground application in conduit. I asked about XHHW and said that I plan to run it underground, outside, in conduit (i.e. underground, wet), but the person insisted that THHN is OK. I am a bit confused. I thought this is not allowed per the NEC?

 

[Oso954]

Most if not all, THHN sold today will also carry a THWN rating. You can read the printed info on the wire or on the mfg spec sheet.

It is perfectly acceptable for your project.

 

[rjniles]

Today's THHN is dual rated as THWN