NEC 2020 article 230.71(B)(3) and Switchboards

Tainted

Tainted

Senior Member
Location
New York
Occupation
Engineer (PE)
NYC just adopted the 2020 NEC with amendments... Is article 230.71(B)(3) saying we cannot have more than 1 service service disconnect in a single vertical switchboard section?

For example Let's say I have a Siemens switchboard with 3 service disconnects on a single section. The service disconnects are Vacu-Break type switches.
 
Maybe if those meet the wording of 230.71(B)(4). I'm not familiar with such switchgear.

Mind you I'm not a supporter of this change but I believe the intention was to prohibit exposed bussing on the supply side of the service disconnect. So if these switches attach to bussing in a vertical section, then maybe still no? Hopefully others more familiar with switchgear will chime in. I'm somewhat doubtful the switchgear has caught up to the new requirements because I'm still not really seeing it in lower amperage/voltage stuff.
 
jaggedben said:
Maybe if those meet the wording of 230.71(B)(4). I'm not familiar with such switchgear.

Mind you I'm not a supporter of this change but I believe the intention was to prohibit exposed bussing on the supply side of the service disconnect. So if these switches attach to bussing in a vertical section, then maybe still no? Hopefully others more familiar with switchgear will chime in. I'm somewhat doubtful the switchgear has caught up to the new requirements because I'm still not really seeing it in lower amperage/voltage stuff.
Click to expand...
Even if you get a single generic standalone service disconnect, it will still have exposed bussing when you open it
 
Tainted said:
Even if you get a single generic standalone service disconnect, it will still have exposed bussing when you open it
Click to expand...
Not anymore. Not if it meets the new standards, to my understanding.

Older fused disconnects and breaker enclosures didn't necessarily have exposed bussing either. (When I say bussing I mean bussing, not terminals.) But in any case, supply side bussing and terminals are supposed to have covers or guards now.
 
jaggedben said:
Not anymore. Not if it meets the new standards, to my understanding.

Older fused disconnects and breaker enclosures didn't necessarily have exposed bussing either. (When I say bussing I mean bussing, not terminals.) But in any case, supply side bussing and terminals are supposed to have covers or guards now.
Click to expand...

exposed bussing or terminals cannot be avoided when opened, I don't get the point.

If each Vacu-Break switch is in it's own box I don't see why this wouldn't be allowed.

I think this warrants a letter to the NYC electrical code interpretation committee.. which I will be writing to soon
 
Tainted said:
exposed bussing or terminals cannot be avoided when opened, I don't get the point.
Click to expand...
Obviously at some level of disassembly that is true. But the idea is that you can turn off the service disconnect OCPD and gain access to the load side terminals to terminate wiring to the OCPD without ever being exposed to unguarded live conductors on the line side of the OCPD.

Cheers, Wayne
 
wwhitney said:
Obviously at some level of disassembly that is true. But the idea is that you can turn off the service disconnect OCPD and gain access to the load side terminals to terminate wiring to the OCPD without ever being exposed to unguarded live conductors on the line side of the OCPD.

Cheers, Wayne
Click to expand...
To me that's virtually impossible with even generic standalone disconnects unless the service from the street is turned off.

Am I missing something? Every service disconnect I've ever seen on the market has exposed line side terminals when enclosure is opened.
 
Tainted said:
Am I missing something? Every service disconnect I've ever seen on the market has exposed line side terminals when enclosure is opened.
Click to expand...
All of those disconnects are not in compliance with the 2020 NEC 230.62, in particular 230.62(C), which is what I paraphrased in my previous quote. Most likely those manufacturers have modified their designs, or come out with supplementary guards that can be installed to comply with 230.62(C).

Edit: for a somewhat dated document from one manufacturer on this topic, see:


Cheers, Wayne
 
Tainted said:
To me that's virtually impossible with even generic standalone disconnects unless the service from the street is turned off.

Am I missing something? Every service disconnect I've ever seen on the market has exposed line side terminals when enclosure is opened.
Click to expand...
As I alluded to earlier, as you see new equipment coming from the factories now you are going to see there are additional guards and covers that make that not true anymore. Anything suitable for use as service equipment. Yes, it's true that old stuff has exposed line-side terminals and bussing and will be as long as the old stuff remains and is grandfathered.
 
wwhitney said:
All of those disconnects are not in compliance with the 2020 NEC 230.62, in particular 230.62(C), which is what I paraphrased in my previous quote. Most likely those manufacturers have modified their designs, or come out with supplementary guards that can be installed to comply with 230.62(C).

Edit: for a somewhat dated document from one manufacturer on this topic, see:


Cheers, Wayne
Click to expand...
Ok I'm probably late to the party with this... cause I've been working with NYC 2011 electrical code for a looong time

I hope manufacturers can make some sort of design that would allow us to have more than 1 service disconnect on a single switchboard section... It probably isn't that hard to do too but I hope there's something in the market right now...
 
Tainted said:
Ok I'm probably late to the party with this... cause I've been working with NYC 2011 electrical code for a looong time

I hope manufacturers can make some sort of design that would allow us to have more than 1 service disconnect on a single switchboard section... It probably isn't that hard to do too but I hope there's something in the market right now...
Click to expand...
UL 67 makes that very difficult to do. It requires that the separate compartment required comply with the requirements in UL 50 for a junction box.
 
don_resqcapt19 said:
UL 67 makes that very difficult to do. It requires that the separate compartment required comply with the requirements in UL 50 for a junction box.
Click to expand...
I see...

The biggest problem I will face in the future when designing these systems is the fact that having only 1 service switch per section will increase the amount of space needed in the electrical room. This will bring hardship in existing buildings...
 
Tainted said:
I see...

The biggest problem I will face in the future when designing these systems is the fact that having only 1 service switch per section will increase the amount of space needed in the electrical room. This will bring hardship in existing buildings...
Click to expand...
Switchgear normally complies, but as you say, that requires more space than switchboards.
 
I am still confused by 230.62(c)...

Let's say I have a standalone 2000A service disconnect. The only way to replace the 2000A fuse is to unscrew the old one and put a new one in. How would it be possible to have a barrier and be able to replace a fuse? It's impossible. You would have to unscrew the line side of the old fuse to put the new fuse in...
 
You must log in or register to reply here.
Top