Grounding question

[ggunn]

A club here in Austin has a covered outdoor stage separated by 40' or so from any building. The club owner wants to run power to the stage for PA, lights, and stage power. If he gets a home run circuit run from his service panel to the stage is it a) advisable, b) required, and/or c) code compliant to sink a ground rod at the stage and connect the circuit ground to it?

 

[iwire]

They will have to run a feeder as no more than one branch circuit can supply a seperate building or structure

Once they run a feeder a grounding electrode system is required to be installed.

 

[ggunn]

They will have to run a feeder as no more than one branch circuit can supply a seperate building or structure

Once they run a feeder a grounding electrode system is required to be installed.

It's a small venue and the power requirement at the stage is minimal; a single 20A branch circuit would probably be enough. But couldn't he run a single 240V multiwire branch circuit feeding a pair of GFI outlets at the stage? If so, would a ground rod at the stage be needed?

 

[Dennis Alwon]

It's a small venue and the power requirement at the stage is minimal; a single 20A branch circuit would probably be enough. But couldn't he run a single 240V multiwire branch circuit feeding a pair of GFI outlets at the stage? If so, would a ground rod at the stage be needed?

Yes you can run a MWBC and no electrode is needed- 250.32(exception). A service rated disconnect is still required- The service rated disco will change (go away), IMO in 2014

 

[iwire]

It's a small venue and the power requirement at the stage is minimal; a single 20A branch circuit would probably be enough. But couldn't he run a single 240V multiwire branch circuit feeding a pair of GFI outlets at the stage? If so, would a ground rod at the stage be needed?

Sure, if they can get by on 4800 watts max.

But even small venues often use 1000 watt par cans for lighting,

Of course you have seen the place and I have not.


If the structure is metal I would likely bond it to the EGC even if not directly required by the NEC.

 

[zbang]

Yes you can run a MWBC and no electrode is needed- 250.32(exception). A service rated disconnect is still required- The service rated disco will change (go away), IMO in 2014

You can install either a MWBC or a feeder w/ panel, but don't have to actually mount them on the stage; you can use a freestanding pedestal. There has been much argument about whether a single receptacle box on a 4x4 post needs a GES (I maintain it doesn't).

Regarding a GES for the stage itself- how big? is it permanent? For a temporary 12x12 stage, fed entirely with cords from GFCIs, I wouldn't install a rod for the stage; for a 40x40' with full cover in place for the summer in a thunderstorm area, you bet I would. Not sure how much different it would make, but if nothing else, it makes people happy.

 

[iwire]

I would be much less concerned about a ground rod than I was about bonding a metal structure used for entertainment.

I tried to find the video I have seen of a young boy locked onto and getting a shock from a tent pole that had become energized by a DJs lighting equipment that was hung from the tent.



(BTW, per the definition of structure a 4x4 post is one.)

 

[ggunn]

Sure, if they can get by on 4800 watts max.

But even small venues often use 1000 watt par cans for lighting,

Of course you have seen the place and I have not.


If the structure is metal I would likely bond it to the EGC even if not directly required by the NEC.

Actually, I play music on that stage on a monthly basis. Lighting is 2 or 3 clip lights and a couple of strings of Christmas lights.

It's a wooden structure about 8 X 16. He's been providing power from extension cords running across the yard from the building. I know, I know... That's why I'm trying to help him fix it.

If he runs buried metal conduit, then I guess a ground rod would be redundant.

 

[petersonra]

Actually, I play music on that stage on a monthly basis. Lighting is 2 or 3 clip lights and a couple of strings of Christmas lights.

It's a wooden structure about 8 X 16. He's been providing power from extension cords running across the yard from the building. I know, I know... That's why I'm trying to help him fix it.

do you have any groupies yet?

 

[ggunn]

Yes you can run a MWBC and no electrode is needed- 250.32(exception). A service rated disconnect is still required- The service rated disco will change (go away), IMO in 2014

I'm looking at 210.4, and I see that a MWBC must have a disconnecting means which breaks all ungrounded conductors simultaneously, but I don't see where it requires a service rated disco.

 

[iceworm]

I'm looking at 210.4, and I see that a MWBC must have a disconnecting means which breaks all ungrounded conductors simultaneously, but I don't see where it requires a service rated disco.

NEC 2011
225.31
225.36

ice

 

[Dennis Alwon]

NEC 2011
225.31
225.36

ice

Thank you. The except is for residences where a dp, sp or 3 way switch would be compliant. I know Raider made a proposal as well as myself for the 2014. I believe there will be a change on this.

 

[Dennis Alwon]

Here is the Draft Change on that.

225.36 Type. The disconnecting means specified in 225.31 shall be comprised of a circuit breaker, molded case switch, general use switch, snap switch, or other approved means. Where applied in accordance with 250.32(B) Exception, the disconnecting means shall be suitable for use as service equipment. [ROP 4?55]

 

[ggunn]

NEC 2011
225.31
225.36

ice

Thanks for the reference. Looking at the definition of service equipment, it looks to me that the circuit breakers in the main panel can be considered to be service equipment. It seems to me that if the MW branch circuit is being fed by a two pole breaker in a service panel and connected to GFI outlets on the stage, that should be plenty of safeguards and not a violation. Am I missing something?

 

[Dennis Alwon]

Thanks for the reference. Looking at the definition of service equipment, it looks to me that the circuit breakers in the main panel can be considered to be service equipment. It seems to me that if the MW branch circuit is being fed by a two pole breaker in a service panel and connected to GFI outlets on the stage, that should be plenty of safeguards and not a violation. Am I missing something?

You are missing the fact that a disconnect must be at the building, Look at 225.32. Technically you would have to bring the MWBC into a panel or disconnect switch that was service rated. It is a strange rule and I have have no trouble installing a dp a/c disconnect-- of course, they are not service rated.

 

[ggunn]

You are missing the fact that a disconnect must be at the building, Look at 225.32. Technically you would have to bring the MWBC into a panel or disconnect switch that was service rated. It is a strange rule and I have have no trouble installing a dp a/c disconnect-- of course, they are not service rated.

I am mystified, then. I have been on stage in several outdoor venues with stages which are not connected to a building and which have outlets on stage and no disco in sight. How are they doing that?