Garage Service Line Installation

[DIY_mike1]

Greetings,

When our house was built, I anticipated adding a barn/shop at a later time. I had them route 4awg copper wire from the panel to the inside corner of the house/garage nearest where the barn/shop would go some day. Currently the wire is not connected to anything inside the panel - it is just routed.

Based on voltage drop calculations for the 250ft distance to the barn/shop, I have decide to use 2/0 wire to go from the house to the barn/shop. It will be aluminum wire.

I will be mounting a large junction box to the inside of the house/garage to provide ample room for making the 4awg-to-2/0 splices.

Q1) What size box do you recommend. Other threads have talked about Code minimums (6", etc. ). But I am not size limited (lots of space on that wall.) - though I am watching my $. What box would you suggest as best for value and applicability?

Q2) What do you suggest using for the slices. Have heard about split bolts wrapped in a Mastic Pad, but have also heard about the ASR splicer/reducers, and using just electrical tape. Any advice?

Q3) One of the threads made reference to NEC 413.4(G) requiring smooth rounded insulating "fittings" where wires enter the box.... could you please elaborate with an example of such a fittiing (i.e. McMasterCarr, Graingers, HomeDepot, or other, part number)?

Q4) Several threads talked about having an "equipment" ground from the house panel to the garage/barn/shop. To make sure I understand, for 240V service, I need: a 2/0 red, a 2/0 black, a 2/0 white and a bare 1/0 wire (for the ground). Is that correct? I had read somewhere that the ground can be 1 size smaller than the other wires. Correct? Oh.. and it has to be URD wire, correct?

Q5) I am in Colorado (Larimer county). To the best of my knowledge this jurisdiction adheres to the NEC without substantial exceptions. Does anyone know how how deep in the ground I have to bury the wire?

Q6) Once the wire is inside the House/garage and inside the Barn/Shop, does it need to be routed in conduit on the way to the Junction Box , or the Barn/Shop Breaker Box? These are unfinished, uninsulated stick frame walls.

Thanks for all the help.

Mike

 

[Charles (in GA)]

Greetings,

When our house was built, I anticipated adding a barn/shop at a later time. I had them route 4awg copper wire from the panel to the inside corner of the house/garage nearest where the barn/shop would go some day. Currently the wire is not connected to anything inside the panel - it is just routed.

Based on voltage drop calculations for the 250ft distance to the barn/shop, I have decide to use 2/0 wire to go from the house to the barn/shop. It will be aluminum wire.

I will be mounting a large junction box to the inside of the house/garage to provide ample room for making the 4awg-to-2/0 splices.

Q1) What size box do you recommend. Other threads have talked about Code minimums (6", etc. ). But I am not size limited (lots of space on that wall.) - though I am watching my $. What box would you suggest as best for value and applicability?

Q2) What do you suggest using for the slices. Have heard about split bolts wrapped in a Mastic Pad, but have also heard about the ASR splicer/reducers, and using just electrical tape. Any advice?

Q3) One of the threads made reference to NEC 413.4(G) requiring smooth rounded insulating "fittings" where wires enter the box.... could you please elaborate with an example of such a fittiing (i.e. McMasterCarr, Graingers, HomeDepot, or other, part number)?

Q4) Several threads talked about having an "equipment" ground from the house panel to the garage/barn/shop. To make sure I understand, for 240V service, I need: a 2/0 red, a 2/0 black, a 2/0 white and a bare 1/0 wire (for the ground). Is that correct? I had read somewhere that the ground can be 1 size smaller than the other wires. Correct? Oh.. and it has to be URD wire, correct?

URD cannot enter the building, not even to travel to a junction box. Best to use twisted quadplex known as Mobile Home Feeder which is rated as USE-2/RHH/RHW and can be run underground in or not in conduit, and also be run above ground in conduit, inside or out. If the wire you look at has a yellow ground its URD and don't get it, don't think they make any multi rated URD that you will be able to use.

Q5) I am in Colorado (Larimer county). To the best of my knowledge this jurisdiction adheres to the NEC without substantial exceptions. Does anyone know how how deep in the ground I have to bury the wire?

For most residential purposes, and direct burial, go 24 inches and you won't be wrong. If its in conduit, 18 inches.

Q6) Once the wire is inside the House/garage and inside the Barn/Shop, does it need to be routed in conduit on the way to the Junction Box , or the Barn/Shop Breaker Box? These are unfinished, uninsulated stick frame walls.

If its not in a jacket, it has to be in conduit. If you use the MHF, then yes, you will need to use a long sweep from the bottom of the trench to vertical and straight up to your LB or whatever you use to enter the building, then conduit from there to your junction with the other wire.

Thanks for all the help.

Mike

My info added in RED above.
Charles

 

[Norcal]

I am only replying to a couple of questions, a 6X6 will be WAAAAAAAAAAAAAAAAAY too small to transition from 2/0 to a smaller conductor 12X12 would be better, it's like trying to put 15 pounds of manure in a 5 pound bag, and Polaris connectors are your friend rather then split bolts, no need to use Scotchfill & tape like would be needed w/ split bolts, as they require no field applied insulation, other companies like Ilsco have competitive products.

 

[rockwithjason]

Q1) What size box do you recommend. Other threads have talked about Code minimums (6", etc. ). But I am not size limited (lots of space on that wall.) - though I am watching my $. What box would you suggest as best for value and applicability?

norcal is right on this one this will need a 12 x 12 x4 to be anything less than a total ***** to work with

Q2) What do you suggest using for the slices. Have heard about split bolts wrapped in a Mastic Pad, but have also heard about the ASR splicer/reducers, and using just electrical tape. Any advice?

again i am with norcal. mechanical insulated splices like these
http://www.ilsco.com/e2wShoppingCatalog.aspx?parentId=3100012208&parentLink=2100001183:3100012208

Q3) One of the threads made reference to NEC 413.4(G) requiring smooth rounded insulating "fittings" where wires enter the box.... could you please elaborate with an example of such a fittiing (i.e. McMasterCarr, Graingers, HomeDepot, or other, part number)?

if you use conduit a simple plastic bushing that threads onto the connector inside the box will do
http://www.homedepot.com/p/Halex-2-in-Rigid-Plastic-Insulated-Bushing-4-Pack-27526/100169597?N=5yc1vZbohkZ1z117wk

Q4) Several threads talked about having an "equipment" ground from the house panel to the garage/barn/shop. To make sure I understand, for 240V service, I need: a 2/0 red, a 2/0 black, a 2/0 white and a bare 1/0 wire (for the ground). Is that correct? I had read somewhere that the ground can be 1 size smaller than the other wires. Correct? Oh.. and it has to be URD wire, correct?

charles is right on with this one. the cable assembly will have the correct size ground already on board. fyi the equipment ground is sized according to the breaker size and any adjustment factors present in the circuit desigen

Q5) I am in Colorado (Larimer county). To the best of my knowledge this jurisdiction adheres to the NEC without substantial exceptions. Does anyone know how how deep in the ground I have to bury the wire?

norcal again

Q6) Once the wire is inside the House/garage and inside the Barn/Shop, does it need to be routed in conduit on the way to the Junction Box , or the Barn/Shop Breaker Box? These are unfinished, uninsulated stick frame walls.
charles again
Thanks for all the help.

Mike

information added in red

 

[Beemer533]

Greetings,

When our house was built, I anticipated adding a barn/shop at a later time. I had them route 4awg copper wire .....

Based on voltage drop calculations for the 250ft distance to the barn/shop, I have decide to use 2/0 wire to go from the house to the barn/shop. It will be aluminum wire.


Q2) What do you suggest using for the slices. Have heard about split bolts wrapped in a Mastic Pad, but have also heard about the ASR splicer/reducers, and using just electrical tape. Any advice?

......

Thanks for all the help.

Mike

Since you are going from copper to AL, you definitely can't use a regular split bolt...

You will have to go with a Polaris or Ilsco splice as previously mentioned.

 

[DIY_mike1]

Thank you for your replies. So fast too. It's really helpful.

I have a couple of followup questions.

Q) ".......straight up to your LB or whatever you use to enter the building.... " . What does "LB" stand for?

Q) When I connect the 4awg wire to the Breaker Panel in the house, should I just connect direct to the red/black/white/gnd wire terminals, or should I install a set of 60 amp breakers and connect to them. There will be breakers in the box in the barn/shop, do I need breakers back at the house panel as well?

Q) Assuming the splice/junction box is at a 5 feet elevation on the inside wall of the house/garage, once the USE wire leaves the ground, and it gets above the foundation, can I immediately turn, enter the house at about a 1 foot elevation, and then finish rising to the box. Or, do I need to do all the rising outside, and then turn and enter the box. Kind of didn't want an ugly 4 to 5 foot conduit on the outside of the house.

Q) I read somewhere that the box out in the barn/shop needs to be grounded to a grounding rod pounded 4 ft minimum into the ground. But I also read where someone said there have to be two rods. Any advice on this subject?

Q) about the 2/0 wire sizing. I based that decision on the fact that the local Rural Elect Assoc, said that there should not be more than a 3% total drop in voltage from the pole to the loads. 3% of 120v = 3.6v drop. The service line to the house is 250 mcm, and using calculations based on a realistic worst case load of 120A in the house, I figured there was a 1.92 volt drop to the house, so I had only 1.68v of allowable voltage drop left for the 250 ft run to the barn/shop. My calcs said a 1/0 would be just barely big enough, so I went up to 2/0. Do you think that was overkill?

thanks again.

 

[Beemer533]

I think LB is short for L body fitting, or something like that..

Either way, here is an example of an LB; http://www.homedepot.com/p/Cantex-1-2-in-Type-LB-Conduit-Body-R5133663/202043487?N=5yc1vZbohk

 

[dw1]

I think LB is short for L body fitting, or something like that..

Either way, here is an example of an LB; http://www.homedepot.com/p/Cantex-1-2-in-Type-LB-Conduit-Body-R5133663/202043487?N=5yc1vZbohk

Yep, B-Back
L-Left
R-Right
LB,LL,LR

 

[rockwithjason]

Thank you for your replies. So fast too. It's really helpful.

I have a couple of followup questions.

Q) ".......straight up to your LB or whatever you use to enter the building.... " . What does "LB" stand for?

as stated it's a conduit body with a hub out of the back of it

Q) When I connect the 4awg wire to the Breaker Panel in the house, should I just connect direct to the red/black/white/gnd wire terminals, or should I install a set of 60 amp breakers and connect to them. There will be breakers in the box in the barn/shop, do I need breakers back at the house panel as well?

you need a breaker at the house panel to protect the feeder to the shop. seem to recall that a remote building needs a disconnect so a master breaker in the shop panel would cover that.

Q) Assuming the splice/junction box is at a 5 feet elevation on the inside wall of the house/garage, once the USE wire leaves the ground, and it gets above the foundation, can I immediately turn, enter the house at about a 1 foot elevation, and then finish rising to the box. Or, do I need to do all the rising outside, and then turn and enter the box. Kind of didn't want an ugly 4 to 5 foot conduit on the outside of the house.

you can enter as soon as it is physically possible to do so without blocking any covers or access. as stated you need to have a cable that is rated to be inside the wall or you must sleeve it.

Q) I read somewhere that the box out in the barn/shop needs to be grounded to a grounding rod pounded 4 ft minimum into the ground. But I also read where someone said there have to be two rods. Any advice on this subject?

a ground rod or other grounding electrode is required. an 8ft ground rod driven completely into the ground and connected with a solid copper wire, in your case #6 will do, and connected with a connnecter listed for the purpose. these are commonly called acorn clamps and are widely available at any home store

Q) about the 2/0 wire sizing. I based that decision on the fact that the local Rural Elect Assoc, said that there should not be more than a 3% total drop in voltage from the pole to the loads. 3% of 120v = 3.6v drop. The service line to the house is 250 mcm, and using calculations based on a realistic worst case load of 120A in the house, I figured there was a 1.92 volt drop to the house, so I had only 1.68v of allowable voltage drop left for the 250 ft run to the barn/shop. My calcs said a 1/0 would be just barely big enough, so I went up to 2/0. Do you think that was overkill?

overkill in wire is rarely a bad thing.

thanks again.

information in red