Where is the violation?

[charlie b]

I am reviewing a design, and I want to disallow a proposed configuration. But I can?t find an NEC chapter and verse to cite as being violated by the design. It?s an existing small building (500 amp service). The remodel includes a new 200 amp panel protected by its own Main Breaker. The designer wants to feed the new panel by tapping into the service conductors, upstream of the Main Panel. Here are my concerns:
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• <font size="2" face="Verdana, Helvetica, sans-serif">Connecting to a wire that might be owned and controlled by the utility. The plans do not show the meter ? it could be within the Main Panel or outside the building.</font>

<font size="2" face="Verdana, Helvetica, sans-serif"></font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Overcurrent protection for the new feeder. I can?t tell if the Tap Rules are satisfied, since the plans do not show the rating of the service conductors, nor the method by which they are protected, nor the rating of that protection, nor the length of the tap.</font>

<font size="2" face="Verdana, Helvetica, sans-serif"></font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Connecting upstream of the point at which neutral to ground bond is made. 250.24(B) says you can?t connect N ? G downstream of the service disconnect. But this is upstream, and the plans do not show any grounding or bonding details.</font>

<font size="2" face="Verdana, Helvetica, sans-serif">Other than wanting more information on the drawings, am I missing something? Is there any way this configuration could be code-compliant? If not, what article(s) should I cite as the problem area(s)?

 

[pierre]

Re: Where is the violation?

Generally this type of installation is permitted. You do not follow the requirements of 240.21 as these are not feeders, but service conductors.
Tapping service conductors is permitted, and as long as the calculated load is not over the permitted load rating, you can do this.


Is this tap being installed inside of the building?

Pierre

 

[jimwalker]

Re: Where is the violation?

"Connecting upstream of the point at which neutral to ground bond is made. 250.24(B) says you can?t connect N ? G downstream of the service disconnect. But this is upstream, and the plans do not show any grounding or bonding details."

Charlie it seems if the new panel is up stream then would that cause a violation of the old panel witch is now downstream ?

 

[charlie]

Re: Where is the violation?

1 - If the service conductors are owned and controlled by the electric utility, ask for permission to tap into them but have the existing and future loads at your fingertips.

2 - If you are tapping service conductors, the rules in 240.21 do not apply.

3 - Grounding of equipment ahead of the main disconnecting means is done to the grounded conductor and should not be a problem.

Generally speaking, this is not a good idea since the original service conductors were probably sized for the existing loads and not for the additional service equipment.

 

[roger]

Re: Where is the violation?

Charlie B, 230.72 jumps out at me.

Roger

[ January 17, 2005, 06:31 PM: Message edited by: roger ]

 

[charlie]

Re: Where is the violation?

WOW!, why don't we all answer at the same time.

 

[roger]

Re: Where is the violation?

Originally posted by charlie:
WOW!, why don't we all answer at the same time.

OK

Roger

 

[hurk27]

Re: Where is the violation?

Connections up stream from the main service disconnect could be a 230.40 exception 1 installation, but I would be concerned if it meets 230.72 requirements. The other thing is what will be the total load placed upon the service conductors and does this building still use the 500 amp to the limit or is there room to add this load to these conductors. Is this building a dwelling or other?

 

[charlie b]

Re: Where is the violation?

I'll try to sneak this in before anyone else replies.

Many thanks for the quick responses. To address your questions and your points:
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• <font size="2" face="Verdana, Helvetica, sans-serif">Pierre: The tap point is inside the building.</font>

<font size="2" face="Verdana, Helvetica, sans-serif"></font>

• <font size="2" face="Verdana, Helvetica, sans-serif">The plans do not show the size of the service conductors.</font>

<font size="2" face="Verdana, Helvetica, sans-serif"></font>

• <font size="2" face="Verdana, Helvetica, sans-serif">The plans do not provide either the calculated service load or the measured service load (30-day readings or 1 year utility demand). They only show the load on the new panel.</font>

<font size="2" face="Verdana, Helvetica, sans-serif"></font>

• <font size="2" face="Verdana, Helvetica, sans-serif">Neither the plans nor the specs require the panel to be Service Entrance rated.</font>

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[hurk27]

Re: Where is the violation?

Ok WoW again

 

[charlie]

Re: Where is the violation?

Charlie, everything is half baked. You need to cool your jets and wait for solid information.

 

[charlie b]

Re: Where is the violation?

Originally posted by roger: Charlie B, 230.72 jumps out at me.

The two panels (the existing Main, with its Main Breaker, and the new panel, with its Main Breaker) are about 8 feet apart on the same wall of a room inside the building. Does that comply with 230.72?

Originally posted by hurk27: Connections up stream from the main service disconnect could be a 230.40 exception 1 installation, but I would be concerned if it meets 230.72 requirements. . . . Is this building a dwelling or other?

The facility is a Medical Office Building on the campus of a large hospital complex in California. I don?t think there are separate types of occupancies involved here. The remodel installs a testing facility for cardio-pulmonary stress testing (i.e., the treadmill exam). I do not know what else is presently in the building, but I?ll bet it is other labs and exam rooms, and I?ll bet it is all under one management. Does that throw out the possibility of using that Exception?

 

[charlie]

Re: Where is the violation?

Charlie, 230.40 Exc. 2 works and 230.72 is up to the AHJ (how close together is considered grouped?).

 

[George Stolz]

Re: Where is the violation?

Seems like 230.40 Exc. 2 was written with this scenario in mind!

As long as the utility/metering setup is equipped to handle the added load, there doesn't appear to be a problem with this.

What do I know, I'm a housemonkey...

 

[petersonra]

Re: Where is the violation?

sounds like you should disapprove the plan review based on insufficibnt information

 

[charlie b]

Re: Where is the violation?

That is exactly what I did. Many thanks for all the responses.

 

[pierre]

Re: Where is the violation?

I don't know if I would disapprove the plans yet, I would request more info first.

Pierre

 

[charlie b]

Re: Where is the violation?

Let me change the wording slightly, to clarify my role. I am not in a position to ?approve? or ?disapprove.? This is not a ?plan review? situation. I am performing a ?Quality Control Review? of work done by another engineer. What I did was to write up several comments on the proposed installation, essentially asking that more information be included in the plans (i.e., to show that it is OK as designed), or in the alternative, to revise the plans to sub-feed the new panel from a breaker on the Main Panel.