Panel main disconnect

Status
Not open for further replies.

pfalcon

Senior Member
Location
Indiana
For an industrial machine, yes. See NFPA79:2007:5.3.2 as a reference. Don't forget the additional requirements for LOTO and the like. So a qualified yes.
 

iwire

Moderator
Staff member
Location
Massachusetts
For an industrial machine, yes. See NFPA79:2007:5.3.2 as a reference. Don't forget the additional requirements for LOTO and the like. So a qualified yes.

A shunt trip at the panel does not meet NEC requirements for a disconnect at the machine.
 

renosteinke

Senior Member
Location
NE Arkansas
If you're looking to create an outside disconnect for the power in a building .... this is exactly what shunt trips are made to do. Just be sure to instal the switch 'upside down.'
 

jap

Senior Member
Occupation
Electrician
If you're looking to create an outside disconnect for the power in a building .... this is exactly what shunt trips are made to do. Just be sure to instal the switch 'upside down.'

Actually, if your looking to create an outside disconnect to kill the power inside the building,the shunt trip will not do that at all.There will still be power on the line side of the Shunt Trip Breaker.
 

jap

Senior Member
Occupation
Electrician
That's what I do, but, if you have a feeder from a transformer inside to a Shunt Trip Main Breaker in a Main Distribution Panelboard, and a Shunt Trip Pushbutton for it outside, when you push the button you shunt the Main, kill the power to the panel, kill the control to the pushbutton, but the power is still live on the line side of the Shunt Trip Main.
 

tryinghard

Senior Member
Location
California
Would a shunt trip breaker on an main distribution panel be an alternative to a main (knife switch)?
Could be if your trying to match the function of a knife switch, the feeder to a DP needs to disconnect (open) the feeder circuit, in other words the shunt breaker would be the one supplying the feeder to the DP not in the DP itself - just like a knife switch.

If its not service equipment 408 only requires OCP not a disconnect, is this service equipment - are you asking about a service disconnect?
 

220wire

Member
My question is in regards to a 208v service main disconnect on the exterior

I'm looking at a job that has a bushbutton next to the CT can. The POCO requires a means on the exterior. I've only seen a shunt installed on kitchen equipment and some hospital gear, never on the main

It may satisfy code but the firemen etc that may need to use it probably won't have a clue.
 

tryinghard

Senior Member
Location
California
My question is in regards to a 208v service main disconnect on the exterior

I'm looking at a job that has a bushbutton next to the CT can. The POCO requires a means on the exterior. I've only seen a shunt installed on kitchen equipment and some hospital gear, never on the main

It may satisfy code but the firemen etc that may need to use it probably won't have a clue.
Utility service disconnecting means - 230.70 ?Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors.?

If this pushbutton opens the service disconnect it suffices, around here we can use these and if it?s a service disconnect it must have a placard stating this.
 

jap

Senior Member
Occupation
Electrician
Utility service disconnecting means - 230.70 ?Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors.?

We're allowed to use a pushbutton and shunt trip main around here also. Although it doesnt kill "All " of the power in the building, it does disconnect the conductors from the service-entrance conductors.
 

tryinghard

Senior Member
Location
California
Utility service disconnecting means - 230.70 ?Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors.?

We're allowed to use a pushbutton and shunt trip main around here also. Although it doesnt kill "All " of the power in the building, it does disconnect the conductors from the service-entrance conductors.
The push button shunt system I believe falls under 230.70(A)(3). There are exceptions to 230.2 but the rule is building supplied by only one service. I believe the intent is to kill all power to the building or structure, usually for emergency personel, this can be done by one move of the hand or six. A building with more than one servcie can also be miss-wired in that circuits could mix from differant services - brainless but it's happened. :roll:
 

eprice

Senior Member
Location
Utah
I believe 230.70(A)(3) is saying that if you use a remote control device (shunt trip) to activate the service disconnect, the service disconnect is still required to be located in accordance with 230.70(A)(1). The shunt trip does not take the place of the properly located service disconnect.
My question is in regards to a 208v service main disconnect on the exterior

I'm looking at a job that has a bushbutton next to the CT can. The POCO requires a means on the exterior. I've only seen a shunt installed on kitchen equipment and some hospital gear, never on the main

It may satisfy code but the firemen etc that may need to use it probably won't have a clue.

The NEC does not necessarily require the disconnect to be located on the outside. If you have a disconnect on the inside, that complies with 230.70(A)(1) then the NEC is satisfied. If the POCO requires something more, then they will need to decide whether the shunt trip will satisfy them.
 

jap

Senior Member
Occupation
Electrician
My comment about not killing "All" of the power "In" the building was directed at an indoor Main Distribution Panel with a Shunt Trip Main and a remote outside Pushbutton. Although when you push the button you trip the Main Breaker Inside, there is still power to the Line Side of the Shunt Trip Main inside, therefore you still have power "in" the building.

As far as that goes, that is the case in any instance where a feeder from an outside transformer lands on a Main inside, shunt trip or not.

Im my mind,the only way to truly disconnect the power to the "Inside" of the building is to have the disconnecting means on the "Outside".

If a fireman pushes a shunt trip button outside and sees all the lights go out in the building,he would be sadly mistaken thinking that he had killed all of the power on the inside of the building. There would still be power on the line side of the shunt trip main.Where as a true disconnecting means outside would kill the power to the inside of the building,barring any unforeseen malfunction.

But thats just my 2 cents worth.
 

tryinghard

Senior Member
Location
California
I believe 230.70(A)(3) is saying that if you use a remote control device (shunt trip) to activate the service disconnect, the service disconnect is still required to be located in accordance with 230.70(A)(1). The shunt trip does not take the place of the properly located service disconnect.


The NEC does not necessarily require the disconnect to be located on the outside. If you have a disconnect on the inside, that complies with 230.70(A)(1) then the NEC is satisfied. If the POCO requires something more, then they will need to decide whether the shunt trip will satisfy them.
Well said ? it helps to remember the service disconnects purpose is to physically open the utilities serving conductors not just shut off power. With underground Service Lateral it delineates the Service Point (utility) from Premises Wiring (non-utility).

If the disconnect is installed inside the utility companies want it as close as possible to the entrance of their service conductors because the service is their liability, they own it, and the NEC does not regulate utilities.
 
Status
Not open for further replies.
Top