Another sub panel question

[LaRay]

Okay here is the deal i am facing...I am running a 60 amp feed to a garage thats 130 feet away...My panel in my house is 200 amp...I already have 200 feet of 4/0 - 4/0 -1/0 wire... I have been reading and it looks like everyone now is using a 4 wire deal for seperate neutral and grounds..I would really like to use the wire i have now so should i just get another single strand of wire to run to make it 4 wires or use it as it is...And also i will need something to splice this 4/0 cable down to a #2 cable cause it is way to big for my breakers.

Any help is very appreciated!

 

[Alchymist]

1) You can't run a separate conductor alongside a cable.
2) 4/0 is rated over 200 amps- way overkill for a 60 amp subfeed.
3) Sounds like some leftover entrance cable. Sell it and buy #6 nmb or run single strand #4 in conduit.
4) All above assumes copper cable.

 

[pattenp]

Another issue is that the 4/0-4/0-1/0 that you have might be URD cable and URD does not carry the proper ratings for installation inside of the structure and has to be terminated on the outside. URD is usually only rated as USE-2. Technically URD is not a sheathed cable so another like conductor could be added without anyone knowing the difference. You do need 4 conductors.

 

[LaRay]

What is the best way to terminate it outside... An also to step it down to a smaller cable going inside like a 2 or a 4... I know the 4/0 cable i have are seperate cable's just twisted around one another.

I just don't understand why i can't run a seperate cable for my ground to make my 4th cable.

 

[Alchymist]

As pattenp indicated , technically URD isn't a "cable", so you could add the 4th wire. Now price another 130 feet of 4/0 compared to selling what you have and buying #4 THWN single conductor (X4) for the run. You still haven't answered - copper or aluminum? And there are other considerations for detached sub panel. 4 wires required, ground rod at garage. Probably not a bad idea to check with your local AHJ before committing yourself also.

The devil is in the details!

 

[LaRay]

The cable is aluminum that have with a heavy black coating on it...One reason i was wanting to use this is i have already buried it with both ends out of the ground 10 ft away from house and 10 feet away from garage.

 

[pattenp]

What can I say... you should have asked these questions before you buried it. How deep did you put it? It needs to be at least 24" down if direct buried. You'll need to dig it up to add the forth conductor. The additional conductor needs to run together with the other conductors. This is all NEC but if you are not having it inspected it's all your call.

 

[teamextreme]

I don't have a copy of the latest NEC, did they do away with allowing 3 conductors to feed a separate structure provided there's no other metal connections between them? If not, then it's acceptable to use what he has, but there can't be any other metal connections, ie; other conduit, plumbing pipe, phone lines, etc. going to the structure. I'd have to refresh my memory on the details of ground/neutral bonding and ground rods for this type of install. I don't like running them like this but it always was allowed.

 

[Alchymist]

I don't have a copy of the latest NEC, did they do away with allowing 3 conductors to feed a separate structure provided there's no other metal connections between them? If not, then it's acceptable to use what he has, but there can't be any other metal connections, ie; other conduit, plumbing pipe, phone lines, etc. going to the structure. I'd have to refresh my memory on the details of ground/neutral bonding and ground rods for this type of install. I don't like running them like this but it always was allowed.

3 wire sub feed was done away with in 2008.

 

[tmunsch]

Is this three seperate conductors layed side by side, or were they twisted together before you buried them. They must be suitabe for direct burial. Sounds to me like this might be some twist (triplex) left over from an overhead job, I hope not.

Is the cable marked USE or equivalent?

Are you positive of the size, because you are not supposed to derate the neutral more than two conductor sizes, therefore your neutral should be a minimum of 2/0......

Please do this right and don't take any shortcuts, somebody can get seriously hurt or even killed..

T,

 

[LaRay]

I think ill just pull it back up at just put down 4/4/4/4 cable and make sure it's done right..

Any where other than the chain stores you suggest buying the cable from..i live out in the country so there is nothing near by...I was looking around on the net at some places..

Can someone tell me the correct number or lettered cable i need in aluminum please. These abbreviations before the cable size kinda throws me for a loop and i wanta make sure i get the right thing..

I have done several overhead and meter instulations this is just my first sub panel..

I know it has to be 2ft deep and in conduit anywhere it is outside of the ground.

And to separate the neutral bar and ground in the panel in the garage and drive ground rods for the building also.

I have a 60 amp breaker for the sub panel in the house and a 100 amp breaker in the garage just for a master kill switch. i just need to connect between the both.

Thanks for all the help..

 

[pattenp]

Your best bet is to use Mobile Home Feeder (MHF). The size to use is 2-2-2-4 or 2-2-4-6, which ever is available to you. Usually HD and Lowe's sell this cable. It is a direct bury but can be installed inside as long as it's put in conduit. The #2 is the max size that a 60A breaker will hold. #2 MHF can take a breaker up to 90A.

 

[LaRay]

Thank you thats what i will do

 

[teamextreme]

3 wire sub feed was done away with in 2008.

Thanks Alchy, I need to do a better job of brushing up on the changes. That was always a confusing rule, so glad to see it change to 4 wire only.

 

[pattenp]

The forth wire is the now required equipment ground. See 250.32(B). Exception No 1, is about the previous code conditions that permitted no equipment ground wire.

Thanks Alchy, I need to do a better job of brushing up on the changes. That was always a confusing rule, so glad to see it change to 4 wire only.