Tapping feeder for subpanel using service disconnect.

[TxCobra98]

Good morning everyone. I am planning on installing buried cable for my detached workshop. I plan on 100A (110 / 220) service run 175'. I will be doing all the work myself...I'm not an electrician but retired from the USAF in electronics and worked as an electrician apprentice for a couple years. Finding reliable contract work in my area is a big problem for some reason.
I'd like to simply use buried feeder cable but want suggestions. 2' depth, 2 2 2 4 AL MHF or URD with conduit above ground and #6 wire and 2 ground rods / 6' apart and not tied to the subpanel common at the workshop. ???
I'd like to start my run by tapping onto the main service disconnect located beside the meter box. It is a 200A disconnect with feed thru to the main panel inside of house. I've read replacing that panel with a QO1816M200FTRB type (as an example). I'd appreciate any advice on how best to accomplish this and of the overall project.
Much thanks!

 

[wyliesdiesels]

so you want to tap in on the load side of the breaker?

that can is way to small to make splices in...

also depending on what you will be running, #2 AL is a little small for 175' run...

 

[Zeke]

Wylie, can he use a double lug like this that will take #1? This one says it will fit 1/0.


More importantly, do they make one that is offset? How about stacked?
However, if it's box fill that's the problem just ignore the question.

 

[wyliesdiesels]

Wylie, can he use a double lug like this that will take #1? This one says it will fit 1/0.


More importantly, do they make one that is offset? How about stacked?
However, if it's box fill that's the problem just ignore the question.

i wouldnt want to use that since you have no way to properly insulate it from the metal enclosure

 

[TxCobra98]

i wouldnt want to use that since you have no way to properly insulate it from the metal enclosure

So I should up to #1 AI. What about replacing that disconnect box with a QO1816M200FTRB as an example? Really appreciate the responses.

 

[yatg]

Conventional thing to do is to put a breaker in the house panel for the shop. Then bring the wire back through the wall (in conduit) to head over to the shop.

 

[Bert_]

Space is going to be the biggest energy. I've done it once where I stripped the insulation back a couple inches on the existing wire, slid a Polaris connector over it, and added my tap to the second hole.

Didn't take up too much extra room

 

[TxCobra98]

Space is going to be the biggest energy. I've done it once where I stripped the insulation back a couple inches on the existing wire, slid a Polaris connector over it, and added my tap to the second hole.

Didn't take up too much extra room

So I should be able to come through the bottom of the panel with 1/0 Al using Polaris Connector on the load side?

 

[alfredeneuman]

You need to put insulating bushings on the conduits. Also the ground wire should be bonded to the box if it isn't already.

 

[TxCobra98]

Thanks for the replies. So, I'll use the 1/0 1/0 1/0 Al Triplex URD cable tapped (using the Polaris 3 Tap connectors) from the load side of the service disconnect (given enough room if not I'll research for a different panel); buried 24". Conduit on the above ground both inside / outside to each panel...with insulating bushings (as advised). Sound like a good plan? Again very much appreciated.

 

[bubinga]

Conventional thing to do is to put a breaker in the house panel for the shop. Then bring the wire back through the wall (in conduit) to head over to the shop.

Do they have a 200 Amp "Slave Breaker" (opposed to a main breaker) to go into his main?

 

[wyliesdiesels]

Thanks for the replies. So, I'll use the 1/0 1/0 1/0 Al Triplex URD cable tapped (using the Polaris 3 Tap connectors) from the load side of the service disconnect (given enough room if not I'll research for a different panel); buried 24". Conduit on the above ground both inside / outside to each panel...with insulating bushings (as advised). Sound like a good plan? Again very much appreciated.

You need a 4-wire feeder and single rated URD is not rated for or permitted to be inside structures.

 

[wyliesdiesels]

Do they have a 200 Amp "Slave Breaker" (opposed to a main breaker) to go into his main?

What is a slave breaker?

 

[Walkers]

You need to put insulating bushings on the conduits. Also the ground wire should be bonded to the box if it isn't already.

Are you worried that the PVC conduit is going to rub through the insulation?

 

[sparky 1971]

Are you worried that the PVC conduit is going to rub through the insulation?

NEC 300.4(G) states that wire #4 and larger need to be protected when entering an enclosure. It lists four ways to do it, but a bushing is the easiest and most common. Contrary to what many people think, including journeyman with many years experience, there is no exception for PVC.

 

[yatg]

Thanks for the replies. So, I'll use the 1/0 1/0 1/0 Al Triplex URD cable tapped (using the Polaris 3 Tap connectors) from the load side of the service disconnect (given enough room if not I'll research for a different panel); buried 24". Conduit on the above ground both inside / outside to each panel...with insulating bushings (as advised). Sound like a good plan? Again very much appreciated.

You're feeding from the load side of a 200A breaker. The wire needs to be sized for the breaker. The breaker in the shop panel only serves as a disconnect.

 

[bubinga]

What is a slave breaker?

I don't know, l made it up.
A regular breaker, that would go on one side of the main panel, as opposed to a main.
Or are they all configured the same?

 

[jeepxj]

Thanks for the replies. So, I'll use the 1/0 1/0 1/0 Al Triplex URD cable tapped (using the Polaris 3 Tap connectors) from the load side of the service disconnect (given enough room if not I'll research for a different panel); buried 24". Conduit on the above ground both inside / outside to each panel...with insulating bushings (as advised). Sound like a good plan? Again very much appreciated.

just put a feed-through panel in. you'd gona have a hell of a time with that space.





then run 100a of service to the shop via a breaker.

 

[alfredeneuman]

You're feeding from the load side of a 200A breaker. The wire needs to be sized for the breaker. The breaker in the shop panel only serves as a disconnect.

If it's all outdoors (such as this is) you're allowed feeder taps of an unlimited distance.
NEC 240.21 (5)

 

[wyliesdiesels]

If it's all outdoors (such as this is) you're allowed feeder taps of an unlimited distance.
NEC 240.21 (5)

He’s running it inside the workshop

 

[alfredeneuman]

He’s running it inside the workshop

Where does he say that? It starts outdoors, and if he place a (EDIT> fusible) disconnect or circuit breaker outside of the proposed shop that portion will satisfy the rule. If he uses URD instead of MHF it's not even allowed inside

 

[TxCobra98]

Where does he say that? It starts outdoors, and if he place a disconnect outside of the proposed shop that portion will satisfy the rule. If he uses URD instead of MHF it's not even allowed inside

He's right...I was planning on running it inside but I'll do as you suggest and place a disconnect outside the workshop. I may also do as jeepxj suggests and add a feed-through panel in place of the service disconnect at the house. I also will use:​

1/0-1/0-1/0-2 Notre Dame Quadruplex Aluminum Conductor Underground Direct Burial 600V URD​

Thanks everyone and thanks to all you veterans for your service.​

 

[Walkers]

NEC 300.4(G) states that wire #4 and larger need to be protected when entering an enclosure. It lists four ways to do it, but a bushing is the easiest and most common. Contrary to what many people think, including journeyman with many years experience, there is no exception for PVC.

Interesting. Have you ever seen it cause a problem, or is it just a gotcha in the code because it wasn’t specifically written?

 

[sparky 1971]

Interesting. Have you ever seen it cause a problem, or is it just a gotcha in the code because it wasn’t specifically written?

I don't recall ever actually seeing it happen, but I can see it happening. The ends of the PVC adapters aren't razor sharp but they are sharp enough that if the wire was bent tight enough over the edge and given enough time, it could cut through the insulation.

It's not really a gotcha because it covers all wiring methods where #4 and larger wire is used. People just assume PVC doesn't need a bushing because it's PVC.

 

[Bert_]

You're feeding from the load side of a 200A breaker. The wire needs to be sized for the breaker. The breaker in the shop panel only serves as a disconnect.

Look up the tap rules.

 

[Bert_]

So I should be able to come through the bottom of the panel with 1/0 Al using Polaris Connector on the load side?

It's kind of iffy. You're going to run short on space fast in that little box.

 

[bubinga]

I don't know, l made it up.
A regular breaker, that would go on one side of the main panel, as opposed to a main.
Or are they all configured the same?

l just didn't know if they made a regular breaker, (not a main) in 200 amp.

 

[theoldwizard1]

Good morning everyone. I am planning on installing buried cable for my detached workshop. I plan on 100A (110 / 220) service run 175'.

Ask yourself AGAIN, "Do I really need 100A ?". Most 1 man shops can I easily get by on 60A. You would save a lot of $$$ on a $175' run.

DO IT RIGHT ! Replace that load center with a 2-6 position 200A one and install a ground.

 

[Fasthotrod]

Interesting. Have you ever seen it cause a problem, or is it just a gotcha in the code because it wasn’t specifically written?

I have not seen it cause a problem with PVC damaging the conductors, but the Code doesn't specify that PVC conduit is excluded. A sharp inspector will see it and call you on it. (That, I have seen before.)

 

[TxCobra98]

Ask yourself AGAIN, "Do I really need 100A ?". Most 1 man shops can I easily get by on 60A. You would save a lot of $$$ on a $175' run.

DO IT RIGHT ! Replace that load center with a 2-6 position 200A one and install a ground.

SIEMENS W0404MB1200CT 200 Amp Outdoor Trailer Panel, Gray


I'd like to use this in place of the current disconnect.