Will the real serivce disconnect please stand up?

[infinity]

Looked today at a 400 amp fused disconnect switch (lower right in photo) that was fed on it's line side by SEC's from utility network. The load side feeds a trough with one set of 600 kcmil conductors. In the trough is a tap to feed 2-200 amp meter enclosures which feeds 2-200 amp fused disconnect switches. The question is according to the NEC where is the service disconnect, before or after the meters?

 

[augie47]

To me the 400 amp fusible disconnect would be your service disconnect.
The only exception would be if it was a "meter disconnect" required by POCO and under their control in which case they are normally locked with POCO locks.

No much different from a modular meter center with a main (service) disconenct ahead of the meters and feeder breakers.

 

[infinity]

Since the 400 amp switch is ahead of meters could it be a service disconnect? I would assume that the switch will be locked by the POCO since it contains un-metered conductors.

 

[augie47]

It seems to me that everything depends on it's use. If it's SE rated and has integral or adjacent OCP it seems it fits the bill as service equipment. If POCO required it as a "meter disconnect" then it would seem to fit 230.82(3) and would be ahead of the service equipment.In my experience, they lock them.
I don't see how the meters being on the load side would in itself change anything. As I mentioned above, a multi-meter combo for an apartment complex might have a main disconnect to comply with 230.71 and it would be ahead of the individual unit meters.

 

[infinity]

I don't see how the meters being on the load side would in itself change anything. As I mentioned above, a multi-meter combo for an apartment complex might have a main disconnect to comply with 230.71 and it would be ahead of the individual unit meters.

If the meters are on the load side then the POCO will lock the 400 amp disconnect switch. I'm wondering if the NEC permits the fused service disconnect switch to be locked by the POCO?

 

[david]

Here the utility mandates a disconnect ahead of 480/277v line voltage metering. but they have no horse in he race as to it being fusible, or non-fusible.
Here they do not pad lock them they are sealed.

They do not qualify as a service disconnect if they are non-fusible. if they are fusible and are classified as a service disconnect they create problems for load side bonding of the grounded conductor since the meter enclosure are bonded.

 

[Dennis Alwon]

What type of conduit is that orange stuff-- looks more like plumbing fittings etc

 

[GoldDigger]

What type of conduit is that orange stuff-- looks more like plumbing fittings etc

Installed more recently and not painted yet?
Definitely tight 90 bends.
But if it is not electrical it is infringing on the dedicated space. Not to mention entering panels.

Maybe it is the pressurized dry air for positive pressure ventilation of the equipment?

 

[Dennis Alwon]

Installed more recently and not painted yet?
Definitely tight 90 bends.
But if it is not electrical it is infringing on the dedicated space. Not to mention entering panels.

Maybe it is the pressurized dry air for positive pressure ventilation of the equipment?

Those conduits are entering electrical enclosures.

 

[GoldDigger]

Those conduits are entering electrical enclosures.

"...Not to mention entering panels. "

 

[jim dungar]

What type of conduit is that orange stuff-- looks more like plumbing fittings etc

It looks like orange sprinkler pipe going to pressure monitoring equipment.

 

[Dennis Alwon]

It looks like orange sprinkler pipe going to pressure monitoring equipment.

You may be right but when I blow up the pic (ctrl +) it looks like 2 load centers on the left side-- maybe not

 

[infinity]

What type of conduit is that orange stuff-- looks more like plumbing fittings etc

That's for a fire detection system inside of the POCO network protection compartment which is on the other side of the wall. Air flows through the orange piping and is monitored by the components in the small enclosures on the wall.

 

[pjholguin]

Dennis,

That orange colored PVC is HSSD(High Sensitivity Smoke Detection), I have seen it used in Semi-Conductor Fabs.


PJHolguin

What type of conduit is that orange stuff-- looks more like plumbing fittings etc

 

[kwired]

If the meters are on the load side then the POCO will lock the 400 amp disconnect switch. I'm wondering if the NEC permits the fused service disconnect switch to be locked by the POCO?

Whether it is service equipment or not I believe if the POCO puts a lock on the enclosure it is for the purpose of limiting access to the enclosure. If that enclosure contains overcurrent devices then it is a violation of 240.24(A) as overcurrent devices need to be readily accessible. All POCO specs I have ever seen that want a disconnect ahead of a meter for the purpose of cold sequence meter maintenance wants a non fused disconnect used for this application. Forget code for a moment and think like a POCO representative, if anything they at least do not want to have to respond to service calls to change overcurrent devices in such equipment, making the overcurrent device in customer controlled equipment would help minimize the number of such service calls.