Electrical Question - Everybody loves them!

[Keith Williams]

Yesterday's Tractors Tools Forum,
I recently purchased a log cabin built in 1985.
Cabin is 28 by 32 with a new 200 amp Square D Main Panel I installed before I was allowed to purchase the cabin. It had a Federal Pacific panel before!
It has a garage about 100 feet away that was built in 2000. 100 amp Square D panel fed from a 100 amp breaker in the main panel.
When they built the garage, they ran 1 1/2" PVC pipe from the house to the garage underground.
They ran 2-2-4 Al URD cable when they built it, I would like to add a GROUNDING wire to the circuit.
I believe that the Neutral and Ground are bonded in both locations. Not up to current code but may have been OK in 2000.

Option one: I could simply push thru a bare copper #4 wire. Take the bond out and be done with it.

BUT we all know we just like to think about the future and what we MIGHT do then and I came up with:
Option two: push/pull a second 2-2-4 AL URD cable thru. I would leave the existing two 2 gauge wires as the line wires. Lable them Red and Blue.
Then use the second set of 2 gauge wires for the Neutral and ground. (of course I would have to get them labeled before I pulled them, one white and one green.)
I could then use the two 4 gauge wires to bring back the line output from a generator circuit that I would install in the garage. I would label them. They could also be Red and Blue.
That circuit would land at a 30 amp breaker in my main panel in the house that would have the lock-out installed to prevent back-feed onto the grid.
I would be using the neutral and ground of the main circuit to complete the 4 wires needed for the generator. The generator I have is not bonded, the neutral and ground are separate. I would use the approved male generator outlet at the garage.

WHY option 2??
The 2-2-4 AL URD cable is cheaper per foot than the single #4 copper wire.
I would be upgrading my Neutral to 2 gauge from 4 as it is now.
I would be able to run the generator circuit. I could then run the generator at the garage under cover (with doors open) and not have to drag it from the garage to the house and leave it run outside.

I know you all just like to listen to other people's ideas and comment. So, I gave you something to ponder on.
Comment away and have a GREAT day!
Keith

 

[Russ from MN]

Isn't there already a ground rod at both buildings? Unless you have extremely dry soil I would thing that would suffice.

 

[Jim.ME]

Yesterday's Tractors Tools Forum,
I recently purchased a log cabin built in 1985.
Cabin is 28 by 32 with a new 200 amp Square D Main Panel I installed before I was allowed to purchase the cabin. It had a Federal Pacific panel before!
It has a garage about 100 feet away that was built in 2000. 100 amp Square D panel fed from a 100 amp breaker in the main panel.
When they built the garage, they ran 1 1/2" PVC pipe from the house to the garage underground.
They ran 2-2-4 Al URD cable when they built it, I would like to add a GROUNDING wire to the circuit.
I believe that the Neutral and Ground are bonded in both locations. Not up to current code but may have been OK in 2000.

Option one: I could simply push thru a bare copper #4 wire. Take the bond out and be done with it.

BUT we all know we just like to think about the future and what we MIGHT do then and I came up with:
Option two: push/pull a second 2-2-4 AL URD cable thru. I would leave the existing two 2 gauge wires as the line wires. Lable them Red and Blue.
Then use the second set of 2 gauge wires for the Neutral and ground. (of course I would have to get them labeled before I pulled them, one white and one green.)
I could then use the two 4 gauge wires to bring back the line output from a generator circuit that I would install in the garage. I would label them. They could also be Red and Blue.
That circuit would land at a 30 amp breaker in my main panel in the house that would have the lock-out installed to prevent back-feed onto the grid.
I would be using the neutral and ground of the main circuit to complete the 4 wires needed for the generator. The generator I have is not bonded, the neutral and ground are separate. I would use the approved male generator outlet at the garage.

WHY option 2??
The 2-2-4 AL URD cable is cheaper per foot than the single #4 copper wire.
I would be upgrading my Neutral to 2 gauge from 4 as it is now.
I would be able to run the generator circuit. I could then run the generator at the garage under cover (with doors open) and not have to drag it from the garage to the house and leave it run outside.

I know you all just like to listen to other people's ideas and comment. So, I gave you something to ponder on.
Comment away and have a GREAT day!
Keith

You might be lucky, but I doubt you can push the #4 copper through that conduit, much less a second 2-2-4.

 

[wp6529]

Logistically you are probably looking at pulling the existing wire out of the conduit and pulling a pull rope in at the same time. Once it's out you may as well pull a new 4 conductor service cable to the garage and pull the additional four conductors for the generator feed in at the same time. Be sure to size the generator a gauge higher (8ga) to account for the extra distance. I did very similar for my old shop, though at the time I was able to use copper THHN for all.

ETA: You still need a ground rod at the garage end, even with the 4 conductor feeder.

 

[Mule Meat]

Pull the 2-2-4 and replace it with a 2-2-2-4 URD.

Doesn't make much sense to me. Pull another line just to feed the main breaker from a generator when you have the wire in place to back feed through the sub panel in the garage already in place.

 

[wp6529]

Doesn't make much sense to me. Pull another line just to feed the main breaker from a generator when you have the wire in place to back feed through the sub panel in the garage already in place.

You can't do that legally or safely. You need to have the transfer switch / interlock back at the main panel. You can run the generator feed through the conduit from the garage, but it has to connect only at the interlocked backfeed breaker in the main panel.

 

[Scott 730]

Pull the 2-2-4 and replace it with a 2-2-2-4 URD.

Doesn't make much sense to me. Pull another line just to feed the main breaker from a generator when you have the wire in place to back feed through the sub panel in the garage already in place.

The interlock for the genny breaker needs to be in the main panel.

 

[Keith Williams]

You might be lucky, but I doubt you can push the #4 copper through that conduit, much less a second 2-2-4.

Conduit is 1 1/2 inch, plenty of room.

 

[Keith Williams]

Logistically you are probably looking at pulling the existing wire out of the conduit and pulling a pull rope in at the same time. Once it's out you may as well pull a new 4 conductor service cable to the garage and pull the additional four conductors for the generator feed in at the same time. Be sure to size the generator a gauge higher (8ga) to account for the extra distance. I did very similar for my old shop, though at the time I was able to use copper THHN for all.

ETA: You still need a ground rod at the garage end, even with the 4 conductor feeder.

There is already a ground rod at both the Cabin and Garage.

 

[Keith Williams]

Logistically you are probably looking at pulling the existing wire out of the conduit and pulling a pull rope in at the same time. Once it's out you may as well pull a new 4 conductor service cable to the garage and pull the additional four conductors for the generator feed in at the same time. Be sure to size the generator a gauge higher (8ga) to account for the extra distance. I did very similar for my old shop, though at the time I was able to use copper THHN for all.

ETA: You still need a ground rod at the garage end, even with the 4 conductor feeder.

Thanks for commenting!
My thinking is:
I would then be throwing away the 2-2-4 URL, Buying a much more expensive 2-2-2-4 (HD is 3.40/foot). Plus having to buy the 8 Gauge wire (HD 3.25/foot). Total of 6.65 per foot VS 1.90 for 2-2-4 URL. More than 3X the cost. Generator would be using 4 Ga wire in my solution VS 8 GA in yours.

I do agree that I may well have to pull the existing 2-2-4 if for no other reason than to get an exact measurement of the length of wire I need.

 

[John T]

Just in case you are upgrading to the current requirements, either by running all new cable or adding additional wires to what's already there and re configuring, the basics TODAY are as follows: Your old system may be okay and/or may be Grandfathered in, I just can't know from here ???????????

If you power a SUB PANEL fed from a Main Panel, at the Sub the separate Neutral and Ground Busses are electrically insulated and isolated from each other.

The feed for 120/240 from main to sub requires FOUR wires, Two Hots, Neutral, Ground...ONLY at the Main is Neutral Bonded to Ground

If you connect a portable generator to your homes wiring system using a typical power inlet box and cord and are NOT switching the Neutrals
(Home and Genny Neutrals are tied together) the genny should be configured with a FLOATING Neutral. Of course proper backfeed of the grid must be prevented using lockout assemblies or transfer methods etc. I make no comment on the number and size of wires in a raceway and possible addition of more wires, consult NEC tables for those answers.

You are correct, this forum loves electrical questions, those and legal draw out the most responses...

Best wishes be safe, do not take my word for this Im long retired. Where fire and life safety are concerned you may want to at least consider consulting trained professional engineers electricians and the NEC where applicable.

See what other fine sparky gents have to say and can add to this.........

John T

 

[moresmoke]

Thanks for commenting!
My thinking is:
I would then be throwing away the 2-2-4 URL, Buying a much more expensive 2-2-2-4 (HD is 3.40/foot). Plus having to buy the 8 Gauge wire (HD 3.25/foot). Total of 6.65 per foot VS 1.90 for 2-2-4 URL. More than 3X the cost. Generator would be using 4 Ga wire in my solution VS 8 GA in yours.

I do agree that I may well have to pull the existing 2-2-4 if for no other reason than to get an exact measurement of the length of wire I need.

I installed a run of 2-2-2-4 this summer. After shopping prices, I ordered the wire from
https://www.wireandcableyourway.com/
Their price was about half of local with prompt shipping.

To answer your question, I would pull a new 2-2-2-4 for the garage service and use the existing for your generator hookup. The #2 is oversize, but you do end up with a long wire run from the generator to the final destination.

I have a similar setup between my shop and the transfer switch at the meter pole.

 

[Jim.ME]

Conduit is 1 1/2 inch, plenty of room.

Yes, there is room. What can pull through a conduit together with proper lube is different than what will push in alongside an existing cable. What I have seen is there will be twists and turns of the cable already in the conduit, it won't lay perfectly straight and flat. When you try to push another wire/cable through the conduit the two will interact and the one you are trying to push in will bind up when it gets in part way as it works along the existing cable. Good luck YMMV

 

[wp6529]

Yes, there is room. What can pull through a conduit together with proper lube is different than what will push in alongside an existing cable. What I have seen is there will be twists and turns of the cable already in the conduit, it won't lay perfectly straight and flat. When you try to push another wire/cable through the conduit the two will interact and the one you are trying to push in will bind up when it gets in part way as it works along the existing cable. Good luck YMMV

Yes, even if planning to reuse the original wire in some form (not a good idea since it still lacks the 4th conductor needed in any case) your best approach is still to pull the original wire from the conduit while pulling in a pull rope after it, then add the additional conductors, lube well and use the pull rope to pull the whole thing back into the conduit. Since the original wire has already been terminated you will need to ensure plenty of extra at each end of the new conductors and when pulling back into the conduit ensure you stop at the correct point to reconnect the original cable which probably only has a short bit of slack at each end.

 

[wp6529]

Also, when pulling old wire out and a pull rope in it's a good idea to tie a rag on at the start of the pull rope to wipe crud and water out of the conduit. When pulling the wire in you can replace this rag with one saturated in extra cable lube to pre-lube the conduit before the wire. This does not negate the need to lube the wire itself as it's pulled in.

 

[Tony in SD]

My construction crews have lots of experience pulling wires in buried duct. First thing I will say is that buried duct more than a year old will most likely have water in it and a good chance it has dirt in it too. Im not going to say it will be impossible to pull the old cables out or try to add new cables to a duct with existing cables but it will be somewhere between very difficult to impossible. And just because the cables will fit in a duct dose not mean you can fill the duct. NEC only allows a duct to be so full. If your PVC is schedule 80 you are allowed 5 #2 conductors or if it is schedule 40 you are allowed 7 #2 conductors if my memory is correct. As others have said, make sure you use duct lube when pulling wires.

 

[buickanddeere]

Yesterday's Tractors Tools Forum,
I recently purchased a log cabin built in 1985.
Cabin is 28 by 32 with a new 200 amp Square D Main Panel I installed before I was allowed to purchase the cabin. It had a Federal Pacific panel before!
It has a garage about 100 feet away that was built in 2000. 100 amp Square D panel fed from a 100 amp breaker in the main panel.
When they built the garage, they ran 1 1/2" PVC pipe from the house to the garage underground.
They ran 2-2-4 Al URD cable when they built it, I would like to add a GROUNDING wire to the circuit.
I believe that the Neutral and Ground are bonded in both locations. Not up to current code but may have been OK in 2000.

Option one: I could simply push thru a bare copper #4 wire. Take the bond out and be done with it.

BUT we all know we just like to think about the future and what we MIGHT do then and I came up with:
Option two: push/pull a second 2-2-4 AL URD cable thru. I would leave the existing two 2 gauge wires as the line wires. Lable them Red and Blue.
Then use the second set of 2 gauge wires for the Neutral and ground. (of course I would have to get them labeled before I pulled them, one white and one green.)
I could then use the two 4 gauge wires to bring back the line output from a generator circuit that I would install in the garage. I would label them. They could also be Red and Blue.
That circuit would land at a 30 amp breaker in my main panel in the house that would have the lock-out installed to prevent back-feed onto the grid.
I would be using the neutral and ground of the main circuit to complete the 4 wires needed for the generator. The generator I have is not bonded, the neutral and ground are separate. I would use the approved male generator outlet at the garage.

WHY option 2??
The 2-2-4 AL URD cable is cheaper per foot than the single #4 copper wire.
I would be upgrading my Neutral to 2 gauge from 4 as it is now.
I would be able to run the generator circuit. I could then run the generator at the garage under cover (with doors open) and not have to drag it from the garage to the house and leave it run outside.

I know you all just like to listen to other people's ideas and comment. So, I gave you something to ponder on.
Comment away and have a GREAT day!
Keith

Going to have to pull all the conductors out . Add the bare copper #6 , then pull the conductors back into the conduit . Needs a buried ground plate or a pair of ground rods at the garage .
Neutral should not be bonded in the garage panel .

 

[Keith Williams]

My construction crews have lots of experience pulling wires in buried duct. First thing I will say is that buried duct more than a year old will most likely have water in it and a good chance it has dirt in it too. Im not going to say it will be impossible to pull the old cables out or try to add new cables to a duct with existing cables but it will be somewhere between very difficult to impossible. And just because the cables will fit in a duct dose not mean you can fill the duct. NEC only allows a duct to be so full. If your PVC is schedule 80 you are allowed 5 #2 conductors or if it is schedule 40 you are allowed 7 #2 conductors if my memory is correct. As others have said, make sure you use duct lube when pulling wires.

That is useful info. Thanks!
If I remember the code correctly, you only count the line conductors when you are doing the count. So with 2 sets of 2-2-4 I would only have 3 #2's that are conducting when it is live. The two loads and the neutral. The 4th #2 would be the GROUNDING wire. The two #4's would only carry current when the generator is running but, that is still only 5.

 

[John T]

That is useful info. Thanks!
If I remember the code correctly, you only count the line conductors when you are doing the count. So with 2 sets of 2-2-4 I would only have 3 #2's that are conducting when it is live. The two loads and the neutral. The 4th #2 would be the GROUNDING wire. The two #4's would only carry current when the generator is running but, that is still only 5.

Indeed the Equipment GroundING Conductor should carry NO current other than fault current, however Im not up to par on the conduit fill and conductor specs its been too long, so check the NEC where applicable. I think you already indicated the Generator is configured with a FLOATING Neutral which is correct when its Neutral is attached to the Utility Neutral IE Neutrals are NOT switched. Good job taking the time to do this SAFE !!!!

John T

 

[miangus]

Logistically you are probably looking at pulling the existing wire out of the conduit and pulling a pull rope in at the same time. Once it's out you may as well pull a new 4 conductor service cable to the garage and pull the additional four conductors for the generator feed in at the same time. Be sure to size the generator a gauge higher (8ga) to account for the extra distance. I did very similar for my old shop, though at the time I was able to use copper THHN for all.

ETA: You still need a ground rod at the garage end, even with the 4 conductor feeder.

I agree on your wire selection and method selection. However, a ground rod should not be installed at the subpanel with a four-wire system and the bonding screw at the subpanel which should exist and was required in the old system should be removed.