pls sanity check by subpanel plan

[sky jumper]

getting ready to run a 100A feeder to my detached garage. House main is 200A and is completely full, so I have to add some kind of disconnect/main lug panel outside to run the feeder to the garage. the run is 125ft. plan is 2" sch 80 pvc 18" deep with 3ga copper feeders.
questions:
1) what type of disconnect/main lug do I need to tap off the meter socket for the garage feeder? I'm going to hire an eletrician to do that part, but I need to buy the parts.
2) do the 3 main 3ga feeders need to have special colors or markings or can they just be black?
3) the ground conductor needs to be 8ga green, correct?
4) will a Squre D QO120M100C work for the subpanel?
5) do I have to switch to RMC where the conduit surfaces to LB into the garage?
6) anything else I'm missing/need?

 

[sirhc]

subscribed...

 

[acer66]

Can you not combine some circuits to free the needed breaker space or just install a subpanel next to the main panel, that way you would have space for future upgrades in the house?

 

[casmurbax]

I am by far no expert...

have you read this thread? Great info there.
https://www.garagejournal.com/forum/showthread.php?t=356460

I am sure a sparky will chime in....

Adding a panel sounds like a better way to go.

Schedule 80? usually only used if you are going under driveway.

Have you done a load calc?

good luck with your project.

 

[Bert_]

I don't know about others but I don't use customer supplied parts without a good reason. If you want to get a plan fine but why not involve the electrician if you're going to hire one.

 

[radio63]

I'll be shortly doing something very similar. Total run of appx 80 feet. Installing a 100 amp sub panel in detached garage/shop. Feeding off main 200 amp panel. Question with reference to gauge of wire. I see 3 gauge good for 100 amps but have also read where 2 gauge is used at times. I will definitely use copper, not interested in aluminum. Can sparkies confirm 3 gauge is OK for 100 amp line? Thank you!

 

[matt_i]

If you are ordering wire, its a nice touch to have individual colors. However its not required, can phase tape #6 and larger-diameter. A full 500' spool could possibly save some money but at 3 * 125 there's still going to be 125' left over. You could potentially run the ground as the #3 for simplicity and to use up what you have. But a #3 won't land on a standard ground strip as I recall. You'll have to do the math on cost of a full 500' vs order the red, black, white and green to individual lengths. The individual colors of the same size should be the same cost per ft.

As far as the RMC I think its your call about "where" and if it is subject to damage. That is surely the strongest but Sch 80 PVC is pretty tough too.

 

[Marctrees]

I worked as an Electrician for 20 yrs.

For this type of work, I have NEVER seen colored wire.

It is always black, then you mark it accordingly.

Marc

 

[Marctrees]

Sch 80 not needed.

1 1/2" more than adequate.

Grounding wire can be as small even approx #8 IIRC for 100a sub panel.

Supply house will cut individual conductors to your spec'd length.

That is how Electricians do this.. measure, and order individuals cut to footage length.

Marc

 

[Marctrees]

No RMC... you just run the PVC everywhere... all the way to panel.

Marc

 

[Marctrees]

So you go to the Supply house and order 3x "125'" #3, , and 1 x "125'" #8.

FOUR conductors total.

It comes in black... so you buy a roll of White and roll of Green Tape.

The two hots get no coding... the neutral gets white, the ground green.

Keep the wire that you code white well away from the others to avoid any possible screw up.

Actually, just quick mark the ends before you unroll it... then mark more fully later.

Marc

 

[Bert_]

No RMC... you just run the PVC everywhere... all the way to panel.

Marc

Definitely not necessary if you keep the pipe close to the wall. I have seen many broken PVC pipes though. If it could get hit RMC makes for a nice install.

I worked as an Electrician for 20 yrs.

For this type of work, I have NEVER seen colored wire.

It is always black, then you mark it accordingly.

Marc

At least one electrical supply around here stocks multiple colors of wire in for almost every size copper that is commonly used . If they stock white I would order white, it doesn't cost any extra but the time spent taping does.

Aluminum is a different story all the XHHW I get is black.

 

[7635tools]

I worked as an Electrician for 20 yrs.

For this type of work, I have NEVER seen colored wire.

It is always black, then you mark it accordingly.

Marc

Not sure where you’ve worked for the last several years, but I’ve been using colored wire in the #8 through 750mcm size for the last 5 years at least.


Sent from my iPhone using Tapatalk

 

[Jim greengo]

Install a bigger main panel,then feed a sub panel from it.

 

[FordTruckWench]

getting ready to run a 100A feeder to my detached garage. House main is 200A and is completely full, so I have to add some kind of disconnect/main lug panel outside to run the feeder to the garage. the run is 125ft. plan is 2" sch 80 pvc 18" deep with 3ga copper feeders.
questions:
1) what type of disconnect/main lug do I need to tap off the meter socket for the garage feeder? I'm going to hire an eletrician to do that part, but I need to buy the parts.

Generally, you don't just add a second main in parallel with the first! Especially not 125 feet away. (Someone here just recently had to rework their meter to main connection because 5' of unfused wire was too long.)

Two choices:

1) Add a subpanel next to the existing main. Move enough circuits into this sub that you free up two double wide spots in the main: One to feed the nearby sub, and one to feed the garage sub.

2) Add a new main ahead of your existing main, converting the old main into a sub. (You'll have to unbond neutral and ground in this panel.) The new main can then also feed the garage sub.

4) will a Squre D QO120M100C work for the subpanel?

Yes, but the main breaker in it can't be the only breaker on the garage feed. As mentioned above, you also need one on the other end.

 

[matt_i]

I worked as an Electrician for 20 yrs.

For this type of work, I have NEVER seen colored wire.

It is always black, then you mark it accordingly.

Marc

I see wire and cable your way .com listed a lot here, and I have put stuff in my cart when preparing to buy wire. They have all the colors you can think of plus more and its no extra money. Its of course not required but neither is pride in one's work. Definitely the copper doesn't care and functions the same, it just depends on where one sources wire and if not an option, there is always the route of "phase tape". The most critical task with "cut wire" is to get your lengths exact plus a small safety factor

 

[matt_i]

No RMC... you just run the PVC everywhere... all the way to panel.

Marc

Not sure how you can be definitive without seeing the setup.

It ***** to have a piece of PVC broken out by (??) because then its a good job of disconnecting the feed and rolling back wiring past the break, cut deeper into the run to glue in new parts, pull wires back in, which might be very bad if some is buried in concrete and that's where the coupling must go.

If its all inside the center of the wall, great, no issues, if its outside and mindless lawn service contractors can hack it with their diesel powered exmark then perhaps different. If it comes up inside the plane of the finished wall, once again, maybe some consideration about how close it is to foot traffic or rolling loads.

 

[Marctrees]

Not sure how you can be definitive without seeing the setup.

It ***** to have a piece of PVC broken out by (??) because then its a good job of disconnecting the feed and rolling back wiring past the break, cut deeper into the run to glue in new parts, pull wires back in, which might be very bad if some is buried in concrete and that's where the coupling must go.

If its all inside the center of the wall, great, no issues, if its outside and mindless lawn service contractors can hack it with their diesel powered exmark then perhaps different. If it comes up inside the plane of the finished wall, once again, maybe some consideration about how close it is to foot traffic or rolling loads.

It's a residential installation.

RMC 99% not needed for non overhead work.

I am also assuming installer will use on site judgement.


I got out of the trade 24yrs ago, at that time Viking nor Graybar in MN had colored.... that I ever saw anyway.

Marc

Marc

 

[alfredeneuman]

So you go to the Supply house , and 1 x "125'" #8.
The two hots get no coding... the neutral gets white, the ground green.
Marc

According to the Code, any taped marking is only for #4 or larger conductors

 

[Marctrees]

WHOAAAAA...

That is toatl news to me.

Does that mean I did services wrong for 20 yrs...

Or is that new ??

I was always very Code concious, our supply house did not even carry colored stuff in Service sizes.

Marc

 

[Marctrees]

remember, I got out of the Trade 20 + yrs ago.

Marc

 

[Bert_]

According to the Code, any taped marking is only for #4 or larger conductors

I've broken that rule more times than I can count...

 

[Marctrees]

Well, I just put a 100 a sub in my new shop last week..

Taped the white and green.

I have no inspection here in the woods...

Could have used barb wire w a garden hose covering over it !!!!

So, IS THAT a Code change ??



Marc

 

[alfredeneuman]

You CAN, however, strip the insulation off of the black #8 for the length exposed in panels, boxes, etc.
Bare ground conductors are perfectly acceptable. (and save on tape)

 

[Marctrees]

Ya, I know that.

I prefer to not have bare hanging around in the panel, I'll tape it full length in the can.

Sure, I know the can is grounded anyway, I just prefer to leave the Grounding wire insulated.

Marc

 

[alfredeneuman]

Marc,
How do you deal with the grounds of NM cable?

 

[AntonLargiader]

Yes it was a code change; something like 2008. It's been mentioned here before. Affects me because whenever I finally get around to pulling the #6 copper to my garage, I need to buy white even though I have lots of black.

 

[sky jumper]

thanks for the replies. good feedback.

some more info. I already have a 100A sub panel in the house and it too is full. I did do a load calc and I'm nowhere near 200A. maybe 140 if everything in the house is on all at once. neverheless I have no free slots.

FordTruck you said "Add a new main ahead of your existing main, converting the old main into a sub. (You'll have to unbond neutral and ground in this panel.) The new main can then also feed the garage sub."

I think this is essentially what I want to do, but I'm planning to do it outside the house rather than having to run the garage feeder back out. yes it would involve moving the house main panel ground as I understand it. the electrician I talked to basically told me to get everything set up for him and he'd come in and do the connection for $200.

 

[alfredeneuman]

Yes it was a code change; something like 2008.

The minimum (larger than #6) size for remarking in wires in conduit has been around much longer than that.

 

[Marctrees]

Marc,
How do you deal with the grounds of NM cable?

I tape those green, full length.

Also, my 4 or 6 to Rod.



JK... I really don't.

I guess it's just habit to tape it the one coming in w the feed..

And it looks pretty to me !!

Marc