[RE-wrenches] load side taps and NEC 240.21

Bill Brooks billbrooks7 at yahoo.com
Fri Dec 5 18:41:45 PST 2008


Jerry,

 

As pointed out below, this is a load-side bus connection. It would follow
the 120% rule if using the 2008 NEC. Since the guy is buddies with the
inspector that should be no problem. However, you must follow the 2008 NEC
if you want to apply it (tap must be at the opposite end of the bus from the
utility feed and there must be a sign to not move the tap location. Now onto
the  NEC 240.21(B)5  issue-there is no way you can apply that rule and run
inside a building at all. I think it is a ridiculous exception anyway given
the cost of copper and potential damage that an unfused conductor could see.
Just suck it up and put the 200-amp fused disconnect at the 1200 amp gear,
and put an unfused 200-amp disconnect at the inverter-end of story.

 

Bill.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of August Goers
Sent: Friday, December 05, 2008 8:01 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] load side taps and NEC 240.21

 

Jerry -

 

A line tap typically occurs between the utility meter and the main breaker -
not after the main breaker on the load side. It seems that you are
describing a load side tap which follows the 120% rule under 2008 NEC; I
might be misunderstanding the situation. Please clarify. There are few folks
out there who are able handle these large commercial grade interconnections
and I think it is well worth discussing.

 

Good luck! -August 

 

 

 

August Goers

Luminalt Energy Corporation
4000 Irving Street 
San Francisco, CA 94122

 

Office: 415.564.7652
Mobile: 415.559.1525
august at luminalt.com
www.luminalt.com

 

 

  _____  

From: William Miller <wrmiller at charter.net>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Friday, December 5, 2008 4:11:15 PM
Subject: Re: [RE-wrenches] load side taps and NEC 240.21

Jerry:

At a recent John Wiles seminar, John declared that this scenario is not a 
tap and is therefore not covered under the tap rule.  This was news to me, 
but Wiles is considered some sort of guru in compliance discussions.

William Miller


At 03:43 PM 12/5/2008, you wrote:

>Wreches,
>
>
>I have a system where we are tapping onto the bus bars of a 1200 amp panel 
>fed by a 1200 amp main breaker.  The easy place to tap onto the bus bars 
>is the load side of the breaker using the existing bolts.
>
>
>The inverter and utility fused disco are about 200 ft away, and the tap 
>conductors travel about15ft in EMT conduit before leaving the 
>building.  After that the circuit is outdoors.  NEC 240.21(B)5 allows taps 
>of unlimited length for conductors located outside of a building, except 
>at the point of load (in this case supply) termination.
>
>
>Can 20ft of conductor inside the building be covered by being "at the 
>point of load termination", or do I have to comply with NEC 240.21(B)2 and 
>have an OCPD within 25'?
>
>
>The construction foreman for this project is buddies with the inspector, 
>so getting a signed permit won't be a problem but I want this to be a code 
>compliant system.  Can anyone lend some insight to the spirit of 
>240.21(B)2 and 5?
>
>
>Sorry if this has been discussed before, but searching didn't yield any 
>results.
>
>
>Best,
>
>Jerry Caldwell
>
>Recurrent Energy
>
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