Help with sub panel install

[TS6235]

I had a 40x40 shop built. Getting ready to run power to the building. Plan is to set a 90a 2 pole breaker into the 200a house panel, run will be approximately 110 feet to building. I stubbed a 2" conduit when the pad was poured. Also installed UFER ground into the slab. The reading I have been doing looks like I can use 2-2-2-4 MHF.

Couple of questions,

Does the conduit have to connect into the house panel (in the wall) and the shop panel (in the wall) or can I put a protection ring on the knockouts and not connect the conduit into the panels?

Depth of trench? Snohomish County (not in the city)

Can I get just the panel and wire run inspected without having the lighting etc completed?

I'm a bit confused on the number 4 wire, does this wire go to the ground on the house panel to the sub panel ground lug and then another wire go from the sub panel to the UFER ground? If so would this also be number 4?

 

[pattenp]

The MHF where inside the structure needs to be in conduit, that means conduit from outside connected to panel. The #4 is the equipment ground and goes from main panel ground bar to to sub-panel ground bar. The uffer ground wire goes from sub-panel ground bar to uffer ground. Two different wires, two different purposes.

 

[wyliesdiesels]

In your main service panel, if thats where your connecting the feeder, the grounds and neutrals are most likely on the same bar as the neutral bar SHOULD BE bonded in the main service panel.

The GEC going to the UFER needs to be no larger than #4...

 

[theoldwizard1]

Does the conduit have to connect into the house panel (in the wall) and the shop panel (in the wall) or can I put a protection ring on the knockouts and not connect the conduit into the panels?

The inspector will be looking for a "positive" mechanical connection.

 

[Highbeam]

I'm in WA to and your permit will be from the state of WA so same rules. He will want to see a couple of circuits on the subpanel. An outside porch light is required by the man door. Have at least a light and outlet on the inside, even temporary to pass the subpanel inspection.

In theory you could do the rest of the work later with a separate permit. I did it that way.

 

[Ironhorse74]

Labor and Industries adopted the 2014 NEC National Electric Code. I have the same understanding of the subpanel inspection as Highbeam. The top of the conduit has to be 18" below ground.

Brad

 

[RoyBell]

I don't think you can have 2 ground sources for the same feed. At least here you would have to run the ground back to the main panel. Subpanels are not to be bonded (neutral to panel), whereas the main panel is. Usually they only want one ground source per service.

 

[wyliesdiesels]

I don't think you can have 2 ground sources for the same feed. At least here you would have to run the ground back to the main panel. Subpanels are not to be bonded (neutral to panel), whereas the main panel is. Usually they only want one ground source per service.

What do u mean by ground source? U sound confused!

An EGC and a grounding electrode are 2 different animals. Never confuse the 2. U should know this.

A detached structure requires both.

Read this:

http://www.electriciantalk.com/articles/the-confusion-of-the-term-grounding/

 

[RoyBell]

What do u mean by ground source? U sound confused!

An EGC and a grounding electrode are 2 different animals. Never confuse the 2. U should know this.

A detached structure requires both.

Read this:

http://www.electriciantalk.com/articles/the-confusion-of-the-term-grounding/

Maybe I didn't explain well. Your picture says no grounding rod required for sub panel. I am pretty positive a detached structure HERE does not require a ground rod either (only ground to main panel). At least we have never been required to put one in.

My "ground source" statement was in reference to earth grounds.

 

[wyliesdiesels]

Maybe I didn't explain well. Your picture says no grounding rod required for sub panel. I am pretty positive a detached structure HERE does not require a ground rod either (only ground to main panel). At least we have never been required to put one in.

My "ground source" statement was in reference to earth grounds.

If youll notice at the top it says subpanel in same dwelling with service equipment.

Yes grounding electrodes are required for detached structures fed by a feeder from another building and have been for a long time! U need to read NEC 250.32. Im surprised u didn't know this seeing as youre an electrical contractor...

And if it cant be proven that the impedance to earth is 25 ohms or less then a second electrode is required.

I provided that picture because i wasnt quite sure what you were saying.

 

[RoyBell]

If youll notice at the top it says subpanel in same dwelling with service equipment.

Yes grounding electrodes are required for detached structures fed by a feeder from another building and have been for a long time! U need to read NEC 250.32. Im surprised u didn't know this seeing as youre an electrical contractor...

And if it cant be proven that the impedance to earth is 25 ohms or less then a second electrode is required.

I provided that picture because i wasnt quite sure what you were saying.

You are right. That code does state you need a ground rod. However, it only applies if you put a panel in that structure and not just branch wiring to it. That seems odd. What do you think the reasoning of that is?

I am going to have to check the Chicago code book tomorrow to see how it's written in there.

Also curious how they define a detached structure. If there is a breezeway between house and garage, is that considered separate structure? Does there needs to be a break in concrete between the two?

While I am a EC, my work is primarily commercial. Condos/ nursing homes, senior housing. This resi stuff changes daily it seems and we try to stay away from it. We just got nabbed on a building we did outside the city because we didn't have WP/TR gfis under the in-use covers on the porches. I didn't even know WP devices existed. What will they think of next

 

[TS6235]

Thanks guys, have the conduit in the ground at 24". I will run the wire Saturday, going to install one light inside and an outlet. Thanks for the heads up on the porch light. Will include that as well. Plan on getting it inspected in a couple of weeks.

To clarify the wiring on the ground. run the #4 wire from the house ground bar to the sub panel separate grounding bar (separate from the neutral bar), then run another number 4 to the same ground bar to the UFER?

 

[wyliesdiesels]

You are right. That code does state you need a ground rod. However, it only applies if you put a panel in that structure and not just branch wiring to it. That seems odd. What do you think the reasoning of that is?

I am going to have to check the Chicago code book tomorrow to see how it's written in there.

Also curious how they define a detached structure. If there is a breezeway between house and garage, is that considered separate structure? Does there needs to be a break in concrete between the two?

While I am a EC, my work is primarily commercial. Condos/ nursing homes, senior housing. This resi stuff changes daily it seems and we try to stay away from it. We just got nabbed on a building we did outside the city because we didn't have WP/TR gfis under the in-use covers on the porches. I didn't even know WP devices existed. What will they think of next

As i said earlier, grounding electrodes are a different animal than an EGC/grounding conductor.

Both are required for a detached structure.

Grounding electrodes as u should know are for grounding lightning, limiting primary voltage spikes on secondary lines for when a primary line contacts a secondary line, and to limit the voltage to ground.

Grounding electrodes have been required for decades on detached structures.

On the other hand, EGCs/4-wire feeds to detached structures, which is what u might be confused about, were only required starting recently with the 2008 code cycle. Before then 3-wire feeds, where the neutral was used as the low impendance fault path, were allowed for detached structures only when no parallel metalic pathways existed betwen the 2 structures.

Im an in house electrician for a communications/microwave radio company and install on a weekly basis electrical services and grounding electrodes on communications structures as well as communications towers.

Yes, i have seen garages connected via a breezeway considered attached with branch circuit wiring running between.

Dont get me started on TR and WP outlets.

TR outlets just like AFCIs, IMHO are snake oil.

How many decades did we have non TR outlets and how many people died because of it?

Honestly, i believe the manufacturing industry drives the need for some of the codes nowadays! And im not alone in that belief!

*rant over*

Thanks guys, have the conduit in the ground at 24". I will run the wire Saturday, going to install one light inside and an outlet. Thanks for the heads up on the porch light. Will include that as well. Plan on getting it inspected in a couple of weeks.

To clarify the wiring on the ground. run the #4 wire from the house ground bar to the sub panel separate grounding bar (separate from the neutral bar), then run another number 4 to the same ground bar to the UFER?

Yes

 

[RoyBell]

Dont get me started on TR and WP outlets.

TR outlets just like AFCIs, IMHO are snake oil.

How many decades did we have non TR outlets and how many people died because of it?

Honestly, i believe the manufacturing industry drives the need for some of the codes nowadays! And im not alone in that belief!

*rant over*



[/b]

Yes

These AFCI are getting out of control. the City of Chicago only requires sleeping areas to be AFCI. This out of city job required them in every damn room minus the kitchen and bathroom. I had to read up NEC because of the updated codes. Chicago pretty much follows 15 years behind NEC .

I misread the NEC code and thought if smokes were on their own circuit that they did not need to be AFCI. Well, inspector made us put them in. Apparently they are exempt when on "fire detection systems", which I assumed smoke detectors would fall under

@ $50 a breaker, these load centers are getting pricey, not to mention all the extra wiring

I am gonna go back and hide in the city where they don't enforce this kind of nonsense and we can use regular outlets that aren't TR

 

[Crazyjake8493]

We need code-writing panels that consist of engineers and electricians working in the field, not manufacturers of panels and breakers that stand to make an enormous profit on the code updates.