Question about two meters for a dwelling, and grounding

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JJWalecka

JJWalecka

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New England
I am wiring a dwelling with an addition being built on to it. The existing feed is 100 amp. I would like to install a 200 amp two meter bank with two separate disconnects one for the new 100 amp panel located twenty feet from the service equipment (feeding the existing dwelling) and the other disconnect feeding a second 100 amp panel (for the addition) on the second floor, of the addition, located about thirty feet from the service equipment. The home owner said that she didn't think that you could put two meters because it was an "in law apartment".
I am new to residential installations and I'm ignorant as to the specifications for them. The disconnects would protect the conductors inside the dwellings to there corresponding panels.
My other question is that the old panel has a 8 AWG ran to the water meter, I would install a 4 AWG to it in it's place. Can I fish it through the existing dwellings ceiling above the sheet rock and then support it with staples as it enters thje addition. The dwelling doesn't have a crawl space or basement. 250.64(B) seems to tell me otherwise.
250.64 (B) Securing and protection from physical Damage
A Grounding Electrode conductor or its enclosure shall be securely fastened to the surface on which it is carried...
forgive my ignorance in the matter most of my Electrical experience is Commercial applications. I'm trying to establish my own Electrical Contracting Business. Any information would be appreciated. Thank you for your time and effort.

Justin W.
 
Re: Question about two meters for a dwelling, and grounding

Justin, I've done quite a few two gang meter pans so I'll give you my input. Having two meters wouldn't be a nec issue, possibly a utility issue, but i doubt that. I guess you could have six meters on your single family residence, one for each major room, just would have to pay six basic service charges per month.

Are your panels going to be on or near the exterior walls? If they are you can likely skip the disconnects below the meter and use the disconnects in the panels as your service disconnects (providing the panels are rated for use as service equip). This would save you a bit of money and time - the two circuit QO enclosures with 100A breaker which you could use as a disconnect below the meter are about $80 each, then there is the extra wire and time of hooking up your panels as subs.

The distance you can go inside before hitting a disconnect and OCD is determined by your AHJ. Where I am now its 15 feet, In another jurisdiction an inspector told me i needed to have a damn good reason to go over 10 feet.

I dont see any problem with fishing the water bondwhere necessary, It would be protected from physical damage.

Regards,
Ethan.
 
Re: Question about two meters for a dwelling, and grounding

A new rule for 2002 NEC ( and also 2005 NEC ) allows the service switches to be located in each tenant unit. However, you do need to located the service cable on the outside of the building until just before it reaches its service panel.

I do not think that you should have any kind of Code problem with fished #4 grounding electrode conductor. A #8 GEC is supposed to be in cable armor or conduit. If I had to use conduit for a GEC I definitely would not use steel. I would prefer to use PVC conduit as the first choice, aluminum as the second choice, and brass or schedule 40 copper pipe as the last choice. Copper and brass conduit is h#!!atiously expensive and is not available in UL listed.
 
Re: Question about two meters for a dwelling, and grounding

mc5w,
A new rule for 2002 NEC ( and also 2005 NEC ) allows the service switches to be located in each tenant unit. However, you do need to located the service cable on the outside of the building until just before it reaches its service panel.
Click to expand...
what section # or exception is this "new rule" located in?

Roger
 
Re: Question about two meters for a dwelling, and grounding

NEC 230.40 Exception #1. Slightly different wording in 2005 NEC but effectively the same thing.

Also slightly conflicts with 230.72 but there are other similar cretinisms in NEC.
 
Re: Question about two meters for a dwelling, and grounding

I know it is common practice to install a main breaker service panel in each unit of say, a duplex, however where in the code is this permitted? The wording of 230.40 ex 1 is, "...permitted to have one set of service entrance conductors for each service of different characteristics" which means different voltage and/or frequency. Then the commentary in the handbook basically states the same thing but leaves out the "different characteristics" part. Am I missing something?
 
Re: Question about two meters for a dwelling, and grounding

Originally posted by mc5w:
NEC 230.40 Exception #1. Slightly different wording in 2005 NEC but effectively the same thing.
Click to expand...
I thought you would quote that, but that exception doesn't say what you think it says, It would allow 2 or more sets of service drops or laterals to an occupancy for different voltage systems. It does not allow spreading the maximum six disconects all over a building

Roger

[ April 06, 2005, 06:02 AM: Message edited by: roger ]
 
Re: Question about two meters for a dwelling, and grounding

So where does the code specifically allow One service drop/lateral to supply two or more sets of service entrance conductors that supply non-grouped disconnects? We are assuming residential with same characteristics, disconnects located within the same structure.
 
Re: Question about two meters for a dwelling, and grounding

one set of service drops is one service, but the meters may also be considered seperate services by the jurisdiction. Some jurisdictions do not allow two meters on a single family residence. be sure to pre-check with the county/city and poco for any local rules governing two meter applications/restrictions.

paul
 
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