1600a Main Tripping

[electrofelon]

It’s still wild to me that it would trip the 1600a main before the 20a branch!!

Not really surprising when you consider it has gfpe, it's not like it's tripping on instantaneous levels or anything.

 

[hillbilly1]

I would say everyone does that no? And most stores were built before the MLO ban so you could have six mains in a single enclosure.

These are not MLO banned, they use two separate enclosures, so they are still legal. They actually have a third can and conduits for future use. When Nardelli took over, they switched from Square D iLine to two GE gears. Lowes has some older stores that way, but most newer stores have a single ground fault main. Most Best Buy’s have ground fault mains. Some old WalMarts did that, but all Super Centers have two ground fault mains, one for grocery, the other for general merchandise.

 

[electrofelon]

These are not MLO banned, they use two separate enclosures, so they are still legal. They actually have a third can and conduits for future use. When Nardelli took over, they switched from Square D iLine to two GE gears. Lowes has some older stores that way, but most newer stores have a single ground fault main. Most Best Buy’s have ground fault mains. Some old WalMarts did that, but all Super Centers have two ground fault mains, one for grocery, the other for general merchandise.

A service with two to six mains installed in a single enclosure is still legal if it was installed before the ban/change. I am just saying it was and still is common to get around the gfpe requirement by using multiple mains. You can still do it now they just have to be in separate enclosures.

 

[busman]

I would say everyone does that no? And most stores were built before the MLO ban so you could have six mains in a single enclosure.

I must have missed the MLO ban in my continuing education. Could anyone point me to the changed section?

Thanks,

Mark

 

[electrofelon]

I must have missed the MLO ban in my continuing education. Could anyone point me to the changed section?

Thanks,

Mark

230.71 Maximum Number of Disconnects.
Each service shall have only one disconnecting means unless the requirements of 230.71(B) are met.

(B) Two to Six Service Disconnecting Means.
Two to six service disconnects shall be permitted 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. The two to six service disconnecting means shall be permitted to consist of a combination of any of the following:

Separate enclosures with a main service disconnecting means in each enclosure
Panelboards with a main service disconnecting means in each panelboard enclosure
Switchboard(s) where there is only one service disconnect in each separate vertical section where there are barriers separating each vertical section
Service disconnects in switchgear or metering centers where each disconnect is located in a separate compartment

 

[busman]

230.71 Maximum Number of Disconnects.
Each service shall have only one disconnecting means unless the requirements of 230.71(B) are met.

(B) Two to Six Service Disconnecting Means.
Two to six service disconnects shall be permitted 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. The two to six service disconnecting means shall be permitted to consist of a combination of any of the following:

Separate enclosures with a main service disconnecting means in each enclosure
Panelboards with a main service disconnecting means in each panelboard enclosure
Switchboard(s) where there is only one service disconnect in each separate vertical section where there are barriers separating each vertical section
Service disconnects in switchgear or metering centers where each disconnect is located in a separate compartment

Thanks a ton. Don't know how I missed that one. We are only up to 2017, so maybe that's how.

Mark

 

[electrofelon]

Thanks a ton. Don't know how I missed that one. We are only up to 2017, so maybe that's how.

Mark

Yeah we are still on 2017 here in NY.

 

[texie]

It was the garden center! I have to come back with a lift, but we were able to narrow it down to a branch circuit feeding the pole lights. They appear to be newer LEDs. We’ve been getting a ton of rain, ice and wind in the last few weeks. I assume it found its way into a fixture and is creating a ground fault.
It’s still wild to me that it would trip the 1600a main before the 20a branch!!

If you understand the basics of GFPE systems this will not be a surprise. I would suggest you use this experience to motivate yourself to do some studying on GFPE systems. When and why they are used, the ramifications of them on a project and why single level GFPE is often a poor design choice. What you encountered is not that uncommon but better design choices can be much less disruptive to an electrical system.