Yet another garage sub-panel question
I recently moved into a new house (new to me, not “new†new) and now need to set up my shop again. There’s a fairly good size detached garage / shop into which the previous owner had extended an existing circuit from the house for just enough power for garage door opener, one overhead light, and a three-way switch to turn garage exterior lights on/off at house back door.<!—-><!—-> <!—->
<!—-> <!—->
I want to add at least 60 amp 220v sub-panel for my shop equipment, so I’ve trenched almost 200 feet from the existing 200 amp house service over to the garage, approximately 2 feet deep. Have exactly 360 degrees of bends between pull boxes, but I’ll probably assemble conduit as I’m pulling cable. After having read some other threads here, this is my plan. Please comment.<!—-> <!—->
<!—-> <!—->
Put three 4AWG THHN conductors and one 6AWG THHN ground in 1†or 1-1/4†PVC conduit to connect 60 amp two-pole breaker in house main panel to 100 amp sub-panel in garage. Keep neutral and ground bus bars separate in sub-panel and also connect sub-panel ground bus to driven ground stake at garage exterior.<!—-> <!—->
<!—-> <!—->
Question: Can I put 70 amp breaker on the house end with 200 foot run of 4AWG? See any problems with this plan? <!—-><!—->
<!—-> <!—->
<!—-> <!—->Thanks for any input.
Bob
Replies
Good morning,
well, you have done your homework hahahah
with your numbers, you are are the Max. and you may want to consider using #3 . along with the larger conduit .
the #6 ground is plenty,
You are aware that this is not a electricians forum ?
because of the preceding conversatons about this kind of thing, and the fact that you have 360deg. of bends.....I think you should pull the wire after you assemble the run, however, if you have done this in the past , you are probably aware of the difficulty associated with pulling thru PVC......and use GRC steel elbows in place of the PVC.
Tom
Pulling it as he assembles the conduit is still going to be a PITA, even if he ups the size to 1 1/2". With 360 degrees of turns in the run, even emt will flex so bad it will pop fitting loose. He'll have to bury it as he goes, and use schdl 80 PVC on both ends and any other transitions.
Dave
Dave, I guess I left that little step out, oooops, I have clarified that !.....so, glue everything together, use steel 90's and throw it in the ditch ,backfill, clean the pipe, and then pull the wire!
yes sleeving the pipe over wire is a royal pain, it also provides a nice way to pickup little rocks and pebbles along the way but, provides rebob with a lot of aerobic exercise walking back and forth to the end of the wire.....LOL I assumed rebob is working alone, and screwing around with pipe, glue, wire, dirt, mud, letting the joints set , spilling the glue all over everything, and tossing it in as he goes is more headaches than the guy needs , IMHOof course , anybody would have those problems ..even you and I
my most favorite thing lately is watching everybody else struggle with wire pulls ,while I sit in the trailer and yell at them on the radio for taking too long ........:>)
"
Why not conduit to trench, direct burial aluminum, conduit up to panel? Around here they call it trailer wire, two hots, neutral, and ground
Service Entry WireMobile Home Feeder Cable, Southwire
__________________________________________________________________________
Craft@Hrs Unit Material Labor Total
__________________________________________________________________________
Mobile Home Feeder Cable, Southwire
For permanent mobile home connections. 600 volts. Conductors are triple aluminum alloy and color-coded. Allowable ampacity: 90 degrees Celsius conductor temperature, 20 degrees Celsius ambient, earth thermal resistivity (RHO) 90, 100 percent load factor with neutral carrying only unbalanced load. Underwriter's Laboratory Listed.
__________________________________________________________________________
SKU 117738, 2-2-4 Gauge, 6 Conductor, Aluminum, 500' Coil [email protected] Ea 470.00
__________________________________________________________________________
Mobile Home Feeder Cable
__________________________________________________________________________
Craft@Hrs Unit Material Labor Total
__________________________________________________________________________
Mobile Home Feeder Cable
For permanent mobile home connections. 600 volts. Conductors are triple aluminum alloy and color-coded. Allowable ampacity: 90 degrees Celsius conductor temperature, 20 degrees Celsius ambient, earth thermal resistivity (RHO) 90, 100 percent load factor with neutral carrying only unbalanced load. Underwriter's Laboratory Listed.
__________________________________________________________________________
SKU 462714, 2-2-2 Gauge, 4 Conductor, Aluminum, Per Foot [email protected] Ea 1.31
SKU 323724, 2-2-4 Gauge, 6 Conductor, Aluminum, Per Foot [email protected] Ea 1.20
SKU 728693, 4/0-4/0-2/0 Gauge, 4 Conductor, Aluminum, Per Foot [email protected] Ea 2.49
SKU 593313, 2/0-2/0 Gauge, 2/0 Conductor, Aluminum, Per Foot [email protected] Ea 2.19
> Have exactly 360 degrees of bends between pull boxes, ....
I'd look for a way to put another box in the middle. Making the pull easier is way well worth it.
No joke, get a helper to push the wires in while you're pulling. It takes the friction off the first bend and makes it go a lot easier.
-- J.S.
In our area you no longer float the neutral but bond it to the ground and reground the loadcenter at the garage. Call your local electrical inspector and ask, they work for you, that's also a really good time to get a permit.