USE feeder to remote garage

[LPS]

I'm running a 100A feeder to a remote garage and would like to use aluminum USE direct burial cable. My background is manufacturing, so I don't have a lot of experience with this direct burial stuff... This is for a friend who has an existing manufactured home with a combo meter/panel on a pole and he is adding a small garage approximately 100ft away. I was planning to run copper in PVC from this panel, 18" deep and stub up directly into the main breaker panel inside his new building, but less expensive alternative is to run 2-2-2-4 Southwire aluminum at 24" and only use schedule 80 at each end (see wire specs and link below). I can buy the wire by the foot from Home Depot.

My question is about 338.12 (B) (USE uses not permitted). It sounds like USE cannot be run indoors and must be terminated in an enclosure located outdoors. I haven't examined hundreds of residential panels, but it seems like I've seen USE connected to several main breakers in the past. Is it because it's usually rated RHH and RHW...???

Probably a silly question, but I just wanted to make sure.. The building department is making my friend add a footer to his small building, so I'm telling him to go ahead and install the stub up before he pours the additional concrete. I assume the new footer will extend away from the building, so I wouldn't want to have to come back and put in an external J-box.

Thanks for your comments...

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2-2-2-4 : 2awg hot - 2awg hot - 2awg Neutral - 4awg ground

https://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet15

Construction:
Southwire® mobile home feeder consists of four quadruplexed type RHH or RHW-2 or USE-2 Alumaflex® Brand AA-8000 series aluminum alloy compacted conductors. The cable contains 2 triple-extruded phase conductors, a white striped neutral conductor and a green grounding conductor to eliminate the need for field marking per the National Electrical Code. The insulation is sunlight resistant.

 

[Little Bill]

The statement from Southwire that you included at the bottom of your post shows the wire is dual purpose, it can be used to run inside to the panel if it goes directly into the panel from outside via conduit, fittings, etc. If the run inside is not directly into the panel then you would need to run it in conduit.

Also, if there is to be a footer in direct contact with the earth then a CEE must be installed and used as a Grounding Electrode. So either a 20' piece of #4 embedded in the footer or rebar stubbed up in an accessible location at the pour would be needed.

 

[LPS]

The statement from Southwire that you included at the bottom of your post shows the wire is dual purpose, it can be used to run inside to the panel if it goes directly into the panel from outside via conduit, fittings, etc. If the run inside is not directly into the panel then you would need to run it in conduit.

Also, if there is to be a footer in direct contact with the earth then a CEE must be installed and used as a Grounding Electrode. So either a 20' piece of #4 embedded in the footer or rebar stubbed up in an accessible location at the pour would be needed.

Thanks for confirming the wire rating question, and also your comment about the CEE. I didn't even think about that. I was just going to drive two ground rods...

 

[rcarroll]

Also, if there is to be a footer in direct contact with the earth then a CEE must be installed and used as a Grounding Electrode. So either a 20' piece of #4 embedded in the footer or rebar stubbed up in an accessible location at the pour would be needed.

If the engineer didn't require rebar in the footer, you don't have to install rebar or #4 copper in the footer. Unless a local amendment prevails.
Two ground rods will be fine, then

 

[Little Bill]

If the engineer didn't require rebar in the footer, you don't have to install rebar or #4 copper in the footer. Unless a local amendment prevails.
Two ground rods will be fine, then

I doubt an engineer was involved in a small resi garage.
Would you rather tie on to a section of rebar or piece of #4 wire or pound in two rods then run #6 to each?

 

[ActionDave]

2-2-2-4 : 2awg hot - 2awg hot - 2awg Neutral - 4awg ground

You don't need a full size neutral to a resi garage. They make 2-2-4-6, which is more than adequate and usually cheaper than anything else comparable. With either size you need to feed it with a 90A breaker max. The 100A rating for 2AWG is only good for service conductors on a house.

100' of 1 1/4" pvc would take about fifteen to eighteen minutes to install and would be about $1800 cheaper than a locate, dig up and patch of a gopher or rock damaged direct bury wire.

 

[kwired]

You have one other problem though. #2 aluminum only has an ampacity of 90 amps.

It can be used for services and feeders to dwellings at 100 amps because of the allowance in 310.15(B)(7). You are not supplying a dwelling. You must either protect it at 90 amps or increase to at least 1 AWG aluminum.

 

[GoldDigger]

Also, if there is to be a footer in direct contact with the earth then a CEE must be installed and used as a Grounding Electrode. So either a 20' piece of #4 embedded in the footer or rebar stubbed up in an accessible location at the pour would be needed.

That is a common misinterpretation of the Code on this point.
If there is qualifying rebar or other qualifying metal in the footer it must then be used as a CEE and connected to. If there is not qualifying conductive metal in the footer, there is still the option of adding/tying rebar or using copper wire to make a CEE out of the footer. If the latter is done, it must be used, but the requirement for other electrodes is bypassed.
Note that some jurisdictions go beyond the NEC and simply require that a CEE be created and used for certain types of buildings.

 

[kwired]

That is a common misinterpretation of the Code on this point.
If there is qualifying rebar or other qualifying metal in the footer it must then be used as a CEE and connected to. If there is not qualifying conductive metal in the footer, there is still the option of adding/tying rebar or using copper wire to make a CEE out of the footer. If the latter is done, it must be used, but the requirement for other electrodes is bypassed.
Note that some jurisdictions go beyond the NEC and simply require that a CEE be created and used for certain types of buildings.

Seems it isn't all that often a footing doesn't have rebar in it either, but yes if it doesn't have any metallic reinforcement or even if reinforcement is coated with insulating material you do not have to use that footing as a CEE per NEC.

I haven't seen any installed yet, but do see there is a fiberglass reinforcing rod product out there on the market. Seen displays and sample products in big box as well as at local lumberyard.

 

[LPS]

Wow! I didn't even see the 90A ampacity. Thanks for catching my mistake. Someone recommended this wire and I didn't double check... That won't happen again.

Also, thanks for the comments on the concrete encased electrode. I always thought using a CEE was optional... (I've never installed a grounding electrode system, so it hasn't been a big deal)

This is important to me, so just to be clear:

For new construction where concrete is being poured...
A. A CEE is required to be installed. ?
B. A CEE is only required if reinforcing steel is used. ?
C. A CEE may be used as a grounding electrode only if the concrete is in direct contact with the earth. Doing so eliminates the need to any additional grounding electrodes. ?
D. If reinforcing steel is being used but the the concrete is not in direct contact with the earth, no connection is made to the reinforcing steel and two other grounding electrodes are used. ?

For new construction of an additional building fed by a feeder (including EGC) from the main service...
E. The neutral is isolated and the grounding electrode is connected to the grounding bar/enclosure of the building disconnect/panel.
F. The grounding electrode system must meet the same requirements as a building with the normal service even though the neutral is isolated. ?

For existing buildings where no concrete is being poured...
G. Install two ground rods and bond all metal.

What is the most common method for installing CEEs.
H. Stub up rebar into the wall. ? Would this need to be accessible for inspection at a later date?
I. Stub up rebar inside the building. ?
J. Connect a wire the rebar below the surface of the concrete. ?
K. Just install 20ft of bare #4 copper. ?
L. CEEs are not required. Just drive two ground rods and bond all the required metal parts. ?

If you've taken the time to read all this and respond. Thanks

 

[petersonra]

Wow! I didn't even see the 90A ampacity. Thanks for catching my mistake. Someone recommended this wire and I didn't double check... That won't happen again.

Also, thanks for the comments on the concrete encased electrode. I always thought using a CEE was optional... (I've never installed a grounding electrode system, so it hasn't been a big deal)

This is important to me, so just to be clear:

For new construction where concrete is being poured...
A. A CEE is required to be installed. ?

No. You can have a concrete foundation with plastic under it that would otherwise qualify as a CEE but because the concrete is not in direct contact with earth, it is not a CEE.

B. A CEE is only required if reinforcing steel is used. ?

A CEE is not required ever. But if it is there you have to use it. The NEC will tell you what a CEE is.

C. A CEE may be used as a grounding electrode only if the concrete is in direct contact with the earth. Doing so eliminates the need to any additional grounding electrodes. ?

If the concrete is not in direct contact with earth it is NOT a CEE.

D. If reinforcing steel is being used but the the concrete is not in direct contact with the earth, no connection is made to the reinforcing steel and two other grounding electrodes are used. ?

Only one grounding electrode is required. If you use ground rods, you may need two of them to meet the 25 Ohm requirement for ground rods. In most cases it is going to be cheaper just to pound a second rod han to prove one rod meets the 25 Ohm requirement.

For new construction of an additional building fed by a feeder (including EGC) from the main service...
E. The neutral is isolated and the grounding electrode is connected to the grounding bar/enclosure of the building disconnect/panel.

Yes.
F. The grounding electrode system must meet the same requirements as a building with the normal service even though the neutral is isolated. ?
Sort of. Except instead of the GES being connected to the neutral bar, it is connected to the EGC.
For existing buildings where no concrete is being poured...
G. Install two ground rods and bond all metal.
That is one option.

What is the most common method for installing CEEs.
H. Stub up rebar into the wall. ? Would this need to be accessible for inspection at a later date?
I think so.
I. Stub up rebar inside the building. ?
Another option.
J. Connect a wire the rebar below the surface of the concrete. ?
Another option, but probably not to code.
K. Just install 20ft of bare #4 copper. ?
An option.
L. CEEs are not required. Just drive two ground rods and bond all the required metal parts. ?
CEEs are never required. You have to use them if they are there.

If you've taken the time to read all this and respond. Thanks

Hopefully I have not steered you in the wrong direction.

 

[Little Bill]

Wow! I didn't even see the 90A ampacity. Thanks for catching my mistake. Someone recommended this wire and I didn't double check... That won't happen again.

Also, thanks for the comments on the concrete encased electrode. I always thought using a CEE was optional... (I've never installed a grounding electrode system, so it hasn't been a big deal)

This is important to me, so just to be clear:

For new construction where concrete is being poured...
A. A CEE is required to be installed. ?
B. A CEE is only required if reinforcing steel is used. ?
C. A CEE may be used as a grounding electrode only if the concrete is in direct contact with the earth. Doing so eliminates the need to any additional grounding electrodes. ?
D. If reinforcing steel is being used but the the concrete is not in direct contact with the earth, no connection is made to the reinforcing steel and two other grounding electrodes are used. ?

For new construction of an additional building fed by a feeder (including EGC) from the main service...
E. The neutral is isolated and the grounding electrode is connected to the grounding bar/enclosure of the building disconnect/panel.
F. The grounding electrode system must meet the same requirements as a building with the normal service even though the neutral is isolated. ?

For existing buildings where no concrete is being poured...
G. Install two ground rods and bond all metal.

What is the most common method for installing CEEs.
H. Stub up rebar into the wall. ? Would this need to be accessible for inspection at a later date?
I. Stub up rebar inside the building. ?
J. Connect a wire the rebar below the surface of the concrete. ?
K. Just install 20ft of bare #4 copper. ?
L. CEEs are not required. Just drive two ground rods and bond all the required metal parts. ?

If you've taken the time to read all this and respond. Thanks

I worded my earlier post wrong. I said "you must" use the CEE when what I meant was if it is there you must use it. My main point was that using a CEE is a lot easier than driving two rods. So if a footer is being poured and rebar is used and no plastic between the footer and earth, then use the rebar. If no rebar, I would put in a 20' piece of #4 bare and stub it up in an accessible place.

 

[kwired]

Wow! I didn't even see the 90A ampacity. Thanks for catching my mistake. Someone recommended this wire and I didn't double check... That won't happen again.

Also, thanks for the comments on the concrete encased electrode. I always thought using a CEE was optional... (I've never installed a grounding electrode system, so it hasn't been a big deal)

This is important to me, so just to be clear:

For new construction where concrete is being poured...
A. A CEE is required to be installed. ?
B. A CEE is only required if reinforcing steel is used. ?
C. A CEE may be used as a grounding electrode only if the concrete is in direct contact with the earth. Doing so eliminates the need to any additional grounding electrodes. ?
D. If reinforcing steel is being used but the the concrete is not in direct contact with the earth, no connection is made to the reinforcing steel and two other grounding electrodes are used. ?

For new construction of an additional building fed by a feeder (including EGC) from the main service...
E. The neutral is isolated and the grounding electrode is connected to the grounding bar/enclosure of the building disconnect/panel.
F. The grounding electrode system must meet the same requirements as a building with the normal service even though the neutral is isolated. ?

For existing buildings where no concrete is being poured...
G. Install two ground rods and bond all metal.

What is the most common method for installing CEEs.
H. Stub up rebar into the wall. ? Would this need to be accessible for inspection at a later date?
I. Stub up rebar inside the building. ?
J. Connect a wire the rebar below the surface of the concrete. ?
K. Just install 20ft of bare #4 copper. ?
L. CEEs are not required. Just drive two ground rods and bond all the required metal parts. ?

If you've taken the time to read all this and respond. Thanks

250.50 says: "All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system."

250.52(3) is concrete encased electrodes, but read through it to see what it must consist of to qualify as an electrode, if what is present doesn't qualify, you do not have to make it comply. Adding additional rebar or #4 copper is still an option if you want to create a CEE where there is not already a qualifying CEE present.

They changed wording several years ago to what it now says, it used to say "where availabe" which many took a CEE already installed before electricians were ever on the site to mean it isn't available and was not necessary to use it.