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#81634 - 09/04/02 12:50 AM Service Mast size  
dana1028  Offline
Joined: Jan 2002
Posts: 163
San Carlos, CA
Some inspectors and myself are having a disagreement.

Scenario: Murray 200A combo panels (meter, main,distribution) require a 2" hub. One of the inspectors says "logic would follow that a 2-inch mast is required" and he is making electricians prove a 1-1/2 mast is OK.

My argument: This inspector is 'assuming' too much. Just because Murray chooses to simplify their manufacturing process (just one size hub to mfr. and supply for distribution) doesn't mean Murray is mandating a 2" mast (this 2" mast requirement is not in the mfr. written installation instructions that I am aware of). As far as I'm aware there is a 2 x 1-1/2 reducer bushing available and none of us (who are arguing this matter) have found a code section that does not permit a bushing at the hub.

Rkeis says: "Make them show it to you in the code".

I say you cannot make 'logical conclusions' about what a mfr. wants if it's not in the written instructions, and there is no code citation.

(No I don't have the particular model number for this of the guys says he's going to check with Murray.....but then we may be getting into another can of worms - who's he checking with at Murray? I don't think a verbal phone call qualifies as mfr. instructions one way or the other).

...please don't beat me too harshly on this subject...I really am a sensitive caring poet in disguise as an inspector & elect.

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#81635 - 09/04/02 04:23 AM Re: Service Mast size  
TE  Offline
Joined: Aug 2002
Posts: 36
1. Service Mast heads are made from "1/2 up
If 2" is required what are the smaller sizes used for?

2. Hubs are also made in other sizes. Just because the two inch hub is packaged with
meter base doesn't make it required.

3. Most areas I have worked in, the utility
company dictates mast requirements and often exceed NEC requirements.

The only NEC requirements I'm aware of are
1. Meeting conduit fill standards

2. If the service mast is used for support
it shall be of adequate strength. I've never been asked to prove out adequate strength.

3. All raceway fittings shall be identified for use with service masts. Do reducing bushings meet this req?

In all the cost difference between the two sizes is negligible. I would weigh that with the long term effects of getting into much of a debate.

This is all I know, gotta go, guess I was a poet and didn't know it.......

[This message has been edited by TE (edited 09-04-2002).]

#81636 - 09/04/02 08:05 AM Re: Service Mast size  
Bill Addiss  Offline
Joined: Oct 2000
Posts: 3,878
I'm just curious here, why do you think it requires a 2 inch hub if it is not written in any instructions? Or does it come with a hub on it?


#81637 - 09/04/02 10:50 AM Re: Service Mast size  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,853
Brick, NJ USA
Here in NJ, the Utility Co's specify the mast sizes. The last one we did was 2 1/2"
The hubs on the meter cans are interchangeable, so it's not a problem.
PSE&G supplies meter cans, we change-out the hub if needed.
GPU (JCP&L) we have to supply the cans.
The "all-in-one" is not common here.


#81638 - 09/04/02 11:41 AM Re: Service Mast size  
dana1028  Offline
Joined: Jan 2002
Posts: 163
San Carlos, CA
Thanks for your replies - we have resolution!

"I called a Murray representative and he said the sticker indicating 2'' hub for a 200 amp panel is a maximum size hub not a minimum."

#81639 - 09/10/02 07:03 AM Re: Service Mast size  
Redsy  Offline
Joined: Mar 2001
Posts: 2,056
Bucks County PA
Correct me if I'm wrong but a service raceway is only a MAST if it projects through or above the roof and the Service Drop is supported by it. Our PoCo requires 2" minimum.
If it is only attached to the building as a raceway, you could use as small a size conduit as conductor fill requirements dictate.

#81640 - 09/10/02 10:07 PM Re: Service Mast size  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,853
Brick, NJ USA
Yes, IMHO the "mast" term means the RGC that is thru the roof, and supports the drop.
That's how we look at it in NJ


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