Neutral Disconnect Link

[Grouch1980]

Hi all,
I have 2 questions, somewhat related:

1) When you have multiple service switches, including the switches for any fire pumps and the fire alarm system, does every switch (including the fire alarm disconnect switch) require the neutral disconnect link that's required in the NEC?

2) Does the main bonding jumper connection inside each service switch, and the connection to the grounding electrode conductor, happen on the load side of the neutral disconnect link? I would imagine yes, because if you disconnect the neutral link for any servicing, you still want to maintain the GEC connection and the MBJ connection.

Thanks!

 

[ptonsparky]

What is a neutral disconnect link? Where is it found in the NEC?

 

[Hv&Lv]

Are you talking about an EPO?
i dont think fire pumps and such had any emergency off switches If so.

 

[electrofelon]

What is a neutral disconnect link? Where is it found in the NEC?

230.75. One of those things which should be in the product standards and not in the NEC IMO

 

[infinity]

It's a NYC code requirement. It's typically a piece of bus that can unbolted and pulled out. You can see one in the right side of this photo of a 2000 amp service switch where it is labeled.

From the 2011 NYC Electrical Code Amendments:
ARTICLE 408
Switchboards and Panelboards
SECTION 408.60
Section 408.60 – Add new section 408.60 to read as follows:
408.60 Special Requirements. Switchboards shall be listed, approved and constructed in accordance
with UL 891, Eleventh Edition, Standard for Switchboards. Panelboards shall be listed, approved and
constructed in accordance with UL 67, Eleventh Edition, Standard for Panelboards. Additional
construction specifications shall be in accordance with (A) thru (G) below.
(A) Neutral Disconnect Link in Service Switchboards. A bus link shall be provided for disconnecting
the neutral service conductor(s) from the outgoing load neutral conductor(s). Such disconnect link shall
be readily accessible and located downstream of the main bonding jumper and grounding electrode
conductor terminal. In a multi-section switchboard a single neutral disconnect link may be provided for
all service disconnects.
Exception: A single cable lug accommodating a maximum of two cables may be used in lieu of a neutral
disconnect link for service disconnects 800 amperes or less.

 

[ptonsparky]

Thank you.

 

[infinity]

You're welcome here's one in a 4000 amp service.

 

[hillbilly1]

Usually the disconnect link is used for test purposes on ground fault protected gear. The link is disconnected (while gear is de-energized), then a continuity test (or lack of) is done. There should be no continuity between the points if installation is correct. This is required for proper operation of the ground fault switch.

 

[Grouch1980]

Hey guys,
wow, that's a lot of replies, thanks! so wait, is the link a NYC requirement, or a national NEC requirement? NEC has it in article 230.75. and in the NYC electrical code, it's in Article 408.60(A). I would say it's a national requirement no? also, i'm still not sure of my first two questions in my original post.

 

[hillbilly1]

It’s national, I have come behind several gears that the testing contractor failed to reconnect the link after testing. One was in New York. Just north of NYC. New store that was having power issues, thought it would be the generator not bonded, (four pole switch) but it was correct, the link in the MDP was open. They had other issues, but I found that one while I was troubleshooting.

 

[infinity]

Hey guys,
wow, that's a lot of replies, thanks! so wait, is the link a NYC requirement, or a national NEC requirement? NEC has it in article 230.75. and in the NYC electrical code, it's in Article 408.60(A). I would say it's a national requirement no? also, i'm still not sure of my first two questions in my original post.

The answers to your two questions are in the NYC code from post #5. Also this and the NEC requirement are similar but not the same. The NEC does not require the section of bus link as shown in the two photo's.

 

[hillbilly1]

It’s mainly to facilitate ease of testing.

 

[jim dungar]

I would say it's a national requirement no? also, i'm still not sure of my first two questions in my original post.

I believe it is part of the UL standard for switchboards.
I don't live in NY, but I don't think I have ever seen a 4-wire switchboard without one.

 

[Grouch1980]

It’s national, I have come behind several gears that the testing contractor failed to reconnect the link after testing. One was in New York. Just north of NYC. New store that was having power issues, thought it would be the generator not bonded, (four pole switch) but it was correct, the link in the MDP was open. They had other issues, but I found that one while I was troubleshooting.

wow... that's a big oops.

 

[Grouch1980]

The answers to your two questions are in the NYC code from post #5. Also this and the NEC requirement are similar but not the same. The NEC does not require the section of bus link as shown in the two photo's.

got it... i just have to sit down and review this.

 

[Grouch1980]

It's a NYC code requirement. It's typically a piece of bus that can unbolted and pulled out. You can see one in the right side of this photo of a 2000 amp service switch where it is labeled.

ok, i'm following... now, is the NDL also required in service disconnect switches that are not part of a switchboard? I'm assuming yes... and where is that stated in the NYC code? section 408.60(A) only mentions service switchboards.

 

[Grouch1980]

Actually, I think I can answer my own question...

In NYC, because of section 408.60(A) in the NYC electrical code, a service switchboard requires the neutral disconnect links for each service switch (or a single one). Based on section 230.75 however, remote service switches (not part of a switchboard) don't get NDL's, since those switches don't have buswork... so the neutral wires just connect to a regular bus bar. Do i have this right?

On the national level, we only follow section 230.75 (since 408.60 doesn't exist outside NYC)... so there is no neutral link requirements in a service switchboard. All remote service switches (not part of a swbd) are treated as i described above (neutral wires to a regular bus bar). However, 230.75 also says "In a multi-section switchboard, disconnects for the grounded conductor shall be permitted to be in any section of the switchboard"... what is this 'disconnect' they describe? isn't that a neutral disconnect link or no?

 

[electrofelon]

Actually, I think I can answer my own question...

In NYC, because of section 408.60(A) in the NYC electrical code, a service switchboard requires the neutral disconnect links for each service switch (or a single one). Based on section 230.75 however, remote service switches (not part of a switchboard) don't get NDL's, since those switches don't have buswork... so the neutral wires just connect to a regular bus bar. Do i have this right?

On the national level, we only follow section 230.75 (since 408.60 doesn't exist outside NYC)... so there is no neutral link requirements in a service switchboard. All remote service switches (not part of a swbd) are treated as i described above (neutral wires to a regular bus bar). However, 230.75 also says "In a multi-section switchboard, disconnects for the grounded conductor shall be permitted to be in any section of the switchboard"... what is this 'disconnect' they describe? isn't that a neutral disconnect link or no?

Like Jim, Im thinking there is something in the product standards for switchboards, but havnt researched it.

The wording of 230.75 is interesting. First lets just note it does not use the term "neutral disconnect link". Also it says, " a terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permitted for this purpose. I dont see a definition for "pressure connector, but I am thinking that means any mechanical lug or terminal. Thus it seems the only need for a NDL to meet this requirement would be if crimped lugs attached with bolts were used for the grounded conductors as I do not see those as meeting the wording.

 

[infinity]

The wording of 230.75 is interesting. First lets just note it does not use the term "neutral disconnect link". Also it says, " a terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permitted for this purpose. I dont see a definition for "pressure connector, but I am thinking that means any mechanical lug or terminal. Thus it seems the only need for a NDL to meet this requirement would be if crimped lugs attached with bolts were used for the grounded conductors as I do not see those as meeting the wording.

As long as there is a way to remove the neutral (removing the conductor from the terminal or removing the terminal from the connection to the bus) I see that as meeting the requirement of 230.75. The NYC requirement goes one step further for large service equipment.