Maximum Number Of Disconnects

[D4Electric]

I have an existing 400amp meter bank with (6) meters and (6) 100amp breakers feeding an apartment building. The 400amp meter bank is fed underground from the utility company's transformer, and currently has no main disconnecting means. The owner would like to add a 100amp panel with a house meter.
The plan was to use the 10' tap rule and tap the bussing on the existing 400amp meter bank to bring power to a separate meter main panel.
Does this violate NEC 230.71? When I went to submit my plans to the city, they bought this up a question that they wanted to look into...
Thank you for your help!!

 

[iwire]

Yes that is a problem.

If load calculations show the capacity for it feed the new panel from one of the existing disconnects but set up the metering separately.

 

[ggunn]

I have an existing 400amp meter bank with (6) meters and (6) 100amp breakers feeding an apartment building. The 400amp meter bank is fed underground from the utility company's transformer, and currently has no main disconnecting means. The owner would like to add a 100amp panel with a house meter.
The plan was to use the 10' tap rule and tap the bussing on the existing 400amp meter bank to bring power to a separate meter main panel.
Does this violate NEC 230.71? When I went to submit my plans to the city, they bought this up a question that they wanted to look into...
Thank you for your help!!

If you were to install a main disconnecting means you could have as many discos behind it as you want, couldn't you?

 

[augie47]

If you were to install a main disconnecting means you could have as many discos behind it as you want, couldn't you?

yes

 

[iwire]

If you were to install a main disconnecting means you could have as many discos behind it as you want, couldn't you?

For sure, but that is going to be a heck of a lot more money than my suggestion.

I suspect the OP has already told the customer the cost of the job.

 

[Smart $]

Welcome to the forum!

:thumbsup:

...
The plan was to use the 10' tap rule and tap the bussing on the existing 400amp meter bank to bring power to a separate meter main panel.
Does this violate NEC 230.71? When I went to submit my plans to the city, they bought this up a question that they wanted to look into...

Tell the plan reviewer the tap creates a new service entrance conductor which complies with 230.71 as the six disconnect maximum is per service entrance conductor set—not explicitly per service—as stated about the exceptions named thereunder. In this case, 230.40, Exception No. 4

(A) General. The service disconnecting means for each
service permitted by 230.2, or for each set of service-
entrance conductors permitted by 230.40, Exception No. 1,
3, 4, or 5, shall consist of not more than six switches or sets
of circuit breakers, or a combination of not more than six
switches and sets of circuit breakers, mounted in a single
enclosure, in a group of separate enclosures, or in or on a
switchboard or in switchgear. ...

Exception No. 4: Two-family dwellings, multifamily dwellings,
and multiple occupancy buildings shall be permitted
to have one set of service-entrance conductors installed to
supply the circuits covered in 210.25.

210.25 Branch Circuits in Buildings with More Than
One Occupancy.


(A) Dwelling Unit Branch Circuits. Branch circuits in
each dwelling unit shall supply only loads within that dwelling
unit or loads associated only with that dwelling unit.

(B) Common Area Branch Circuits. Branch circuits installed
for the purpose of lighting, central alarm, signal, communications,
or other purposes for public or common areas of
a two-family dwelling, a multifamily dwelling, or a multioccupancy
building shall not be supplied from equipment that
supplies an individual dwelling unit or tenant space.

This new disconnect cannot be grouped with the other six.

 

[iwire]

Welcome to the forum!

:thumbsup:


Tell the plan reviewer the tap creates a new service entrance conductor which complies with 230.71 as the six disconnect maximum is per service entrance conductor set—not explicitly per service—as stated about the exceptions named thereunder. In this case, 230.40, Exception No. 4






This new disconnect cannot be grouped with the other six.

Before going this or any of the suggested methods get the utility and inspector involved.

 

[D4Electric]

Thanks for all of your input!! I have already received approval from the utility company, its just the city I'm dealing with at this point.

 

[Sierrasparky]

Yes that is a problem.

If load calculations show the capacity for it feed the new panel from one of the existing disconnects but set up the metering separately.

Can't do that as each meter needs it's own main or set of breakers. Given that this appears to be a 6 meter pack then there would be more than 6 handles.
I don't see how you can De-group these so they are not grouped and still be in compliance with other codes and rules.

 

[tortuga]

Welcome to the forum!

:thumbsup:


Tell the plan reviewer the tap creates a new service entrance conductor which complies with 230.71 as the six disconnect maximum is per service entrance conductor set—not explicitly per service—as stated about the exceptions named thereunder. In this case, 230.40, Exception No. 4






This new disconnect cannot be grouped with the other six.

++ Agreed, House loads, Exception No. 4

 

[electrofelon]

Can't do that as each meter needs it's own main or set of breakers. Given that this appears to be a 6 meter pack then there would be more than 6 handles.
I don't see how you can De-group these so they are not grouped and still be in compliance with other codes and rules.

Iwire will correct me if I am mistaken, but I think the thought was to jumper-plate that meter, and set up new metering cold sequenced on the load side of that service disconnect. No NEC issue, but potentially a utility issue with a mix of cold and hot sequence metering.

 

[iwire]

Iwire will correct me if I am mistaken, but I think the thought was to jumper-plate that meter, and set up new metering cold sequenced on the load side of that service disconnect. No NEC issue, but potentially a utility issue with a mix of cold and hot sequence metering.

You nailed it.

 

[shortcircuit2]

The plan was to use the 10' tap rule and tap the bussing on the existing 400amp meter bank to bring power to a separate meter main panel.

It is not a TAP if it is to the supply side bussing of the meter bank.

It will violate the listing of the meter bank by tapping its bussing.

 

[iwire]

It will violate the listing of the meter bank by tapping its bussing.

To nit pick that is no more true than saying punching a hole in a NEMA 4 box violates the listing.

UL will say they cannot determine if the modifications in either case are fine or not and determining that is up to the AHJ.

 

[shortcircuit2]

To nit pick that is no more true than saying punching a hole in a NEMA 4 box violates the listing.

If I punch a hole in a NEMA 4 box, I need to use a fitting that is listed to maintain the enclosures NEMA 4 rating. I can not tap the bussing in the meterbank unless the instructions allow me to tap the bussing.

UL will say they cannot determine if the modifications in either case are fine or not and determining that is up to the AHJ.

UL can determine if a tap of the meterbank bussing is fine or not with a "field evaluation"... The AHJ can not determine if a field tapped buss is OK.

 

[iwire]

If I punch a hole in a NEMA 4 box, I need to use a fitting that is listed to maintain the enclosures NEMA 4 rating. I can not tap the bussing in the meterbank unless the instructions allow me to tap the bussing.

Regardless of the fitting you use you have modified the enclosure.

UL can determine if a tap of the meterbank bussing is fine or not with a "field evaluation"... The AHJ can not determine if a field tapped buss is OK.

Here is what UL says in the UL general directory.

Field Modifications

What happens to the Listing if a UL-Listed product is modified in the field?

An authorized use of the UL Mark is the manufacturer’s declaration that the product was originally
manufactured in accordance with the applicable requirements when it was shipped from the factory. When
a UL-Listed product is modified after it leaves the factory, UL has no way to determine if the product
continues to comply with the safety requirements used to certify the product without investigating the
modified product. UL can neither indicate that such modifications ‘‘void’’ the UL Mark, nor that the
product continues to meet UL’s safety requirements, unless the field modifications have been specifically
investigated by UL. It is the responsibility of the Authority Having Jurisdiction (AHJ) to determine the
acceptability of the modification or if the modifications are significant enough to require one of UL’s Field
Engineering Services staff members to evaluate the modified product. UL can assist the AHJ in making this
determination.
An exception for a field modification authorized by UL is when the product has specific replacement
markings. For example, a switchboard may have specific grounding kits added in the field. The
switchboard is marked with a list of specific kit numbers that have been investigated for use in that
particular switchboard. Only grounding kits that are included on the marking on the product have been
investigated for use in that product.
If a party wishes UL to determine if the modifications made to a UL Listed product comply with UL
requirements, the appropriate Field Engineering Service can be initiated to investigate the modifications.
This investigation will only be conducted after UL consults with the AHJ to ensure that UL’s investigation
addresses all areas of concern and meets all of the AHJ’s needs.
If you have any questions or would like to inquire about a Field Evaluation, contact Field Services at
+1-877-UL-HELPS, prompt #2 (+1-877-854-3577) or visit http://www.ul.com/field/index.html.

 

[electrofelon]

It will violate the listing of the meter bank by tapping its bussing.

I agree with Iwire that it really comes down to what the AHJ thinks. They may say yes, no, or yes but only if you get a UL field evaluation. I had a situation a few years ago where I had a metering and main breaker section of a switchboard and the main breaker was bad and obsolete. The AHJ (inspector) was fine with me sawzalling off the bussbars between the metering and main section, bolting on lugs, and running conductors to a new OCPD ina seperate enclosure. He just said, dont drill new holes, and use listed lugs. YMMV

 

[jap]

Power company around here will not hook up to a Main Breaker Terminal box in a group metering setup that has a Main Breaker / Service Disconnect in it.
They will only hook up to a Main Lug Terminal Box regardless of how many individual Meter/Mains are bolted to the load side of it.

JAP>

 

[electrofelon]

Power company around here will not hook up to a Main Breaker Terminal box in a group metering setup that has a Main Breaker / Service Disconnect in it.
They will only hook up to a Main Lug Terminal Box regardless of how many individual Meter/Mains are bolted to the load side of it.

JAP>

? So how does that work with NEC compliance if there are more than 6 meters?

 

[jap]

? So how does that work with NEC compliance if there are more than 6 meters?

I don't know how it is that way but there are several services around here that have group metering main terminal boxes with more than 6 meters bolted onto the side of it.

They will not allow a switch, disconnect, breaker or whatever you want to call it, between the load side of their transformer and the line side of the individual meter bases.

They consider each tenant main its own service disconnect.

JAP>