Service/Feeder Panel

[Bigbri0104]

Hello Again,
This question relates to differentiating between service/main disconnect. I was helping a friend on a service call and took a picture of this installation. The customer had a Generac generator installed with an automatic transfer switch. Does the automatic transfer switch become the main service disconnect and the panelboard installed inside the dwelling is now identified as sub/feeder panel correct? The reason I brought this up in the forum is when the inside panelboard cover was removed, I only viewed three wires installed - Two conductors, one each feeding a busbar and the third terminated on the neutral bar. I did not see a fourth conductor on the ground bar. Is this installation correct, because I was under the impression you needed a 4th wire on the ground bar. I just needed some clarification.

 

[Dsg319]

In many cases the ATS will become the service disconnect. As long as it is service rated. And than that is where your grounding/bonding will take place.

Therefor making the inside panel a sub panel and requiring a 4 wire feeder.

But the 2020 NEC threw a wrench into what already confused people. But if understood correctly you can use to your advantage.

2020 code now requires an “emergency disconnect” outside of single family dwellings. And therefor if you identify your disconnect such as a meter main as your “emergency disconnect “ you bond neutral to case there and can continue your run to the house panel ( service disconnect) as service conductors only needing three wires. But the only downside to this is you now have to get your GEC into the house panel (service disconnect).

So many people myself included will label there meter main as both service disconnect and emergency disconnect as it’s much easier to keep the GEC outside and to cut down on length of it.

 

[Fred B]

Generac offerings for their ATS does not include a Switch Only type, everyone of theirs is with overcurrent device only. This installation makes everything after a "sub panel" subject to the requirements of that including seperating bonding of N/G and 4 conductors for feeder, also moving of the EGCs to the seperate ground bar.
2020 NEC does allow as a result of the exterior disconnect requirement for a switch only and allowing a 3 conductor to the "main panel" after the switch. Again Generac does not offer that option on their ATS.
See this error often by Generac installer who are not electricians, most have been plumbers or mechanics with only the Generac training that ends at the ATS.
Generac's ATS is marked as service disconnect and is bonded with a requirement by them that bonding not be removed. This requirement precludes use as "disconnect only" allowed by 2020. There are ATS by other mfg that offer a switch only without the overcurrent protection present in the Generac.

 

[Bigbri0104]

This Picture would give a better understanding to pervious post.
The Blue Arrow = New Service Disconnect
Orange Arrow = Splice box for inside panelboard & Tap
Yellow Arrow = Feeder Disconnect for outside shop

 

[Bigbri0104]

Good Morning,
For learning purposes as stated earlier in this thread, since the ATS is identified as the service disconnect, and the panel inside the dwelling is identified as a feeder, requiring a fourth conductor and since this installation did not have a fourth conductor (Ground wire) routed to the inside feeder panel, if there was a ground fault condition the overcurrent device would not open. Essential a fourth conductor is required to clear a ground fault. Is that correct?

 

[Dsg319]

Good Morning,
For learning purposes as stated earlier in this thread, since the ATS is identified as the service disconnect, and the panel inside the dwelling is identified as a feeder, requiring a fourth conductor and since this installation did not have a fourth conductor (Ground wire) routed to the inside feeder panel, if there was a ground fault condition the overcurrent device would not open. Essential a fourth conductor is required to clear a ground fault. Is that correct?

As long as the neutral is bonded inside the house panel ground faults will still clear.

Before 2020 code and not identifying this as a emergency disconnect it is a violation and could have “objectionable current”.

Which I guess after 2020 code and labeling this as emergency disconnect as well the “current” wouldn’t be so objectionable. Lol

 

[Bigbri0104]

LOL thanks. If my memory serves me well there was not a bonding screw attached in the feeder panel, but I'm assuming the neutral is bonded in the ATS.

 

[Dsg319]

LOL thanks. If my memory serves me well there was not a bonding screw attached in the feeder panel, but I'm assuming the neutral is bonded in the ATS.

If that’s the case no neutral bond to the feeder panel and no EGC than there won’t likely be any chance of clearing faults in the branch circuits of that panel or if there was a fault to the panel from the feeder conductors.

 

[GarwoodV6]

Good Morning,
For learning purposes as stated earlier in this thread, since the ATS is identified as the service disconnect, and the panel inside the dwelling is identified as a feeder, requiring a fourth conductor and since this installation did not have a fourth conductor (Ground wire) routed to the inside feeder panel, if there was a ground fault condition the overcurrent device would not open. Essential a fourth conductor is required to clear a ground fault. Is that correct?

Yes, a grounding conductor sized per 250.122 is required to all points downstream when wiring the ATS as a service disconnect with the neutral bonded to the GEC inside the ATS. You must separate all neutral and grounds (EGC) beyond the Neutral Bonding point at the Service, i.e. what has now become a sub-panel

 

[GarwoodV6]

Generac offerings for their ATS does not include a Switch Only type, everyone of theirs is with overcurrent device only. This installation makes everything after a "sub panel" subject to the requirements of that including seperating bonding of N/G and 4 conductors for feeder, also moving of the EGCs to the seperate ground bar.
2020 NEC does allow as a result of the exterior disconnect requirement for a switch only and allowing a 3 conductor to the "main panel" after the switch. Again Generac does not offer that option on their ATS.
See this error often by Generac installer who are not electricians, most have been plumbers or mechanics with only the Generac training that ends at the ATS.
Generac's ATS is marked as service disconnect and is bonded with a requirement by them that bonding not be removed. This requirement precludes use as "disconnect only" allowed by 2020. There are ATS by other mfg that offer a switch only without the overcurrent protection present in the Generac.

Technically speaking the ATS utility power 200A breaker IS a switch and would qualify to be used as an emergency disconnect per NEC.
However, Generac's warranty may disallow using theIr ATS in this manner. In this case I believe that the NEC would defer to their "follow the eqpt. Mfg. installation instructions" clause.
Makes for a lot more work for the electrician, and expense for the homeowner adding an a generator and ATS system.

 

[suemarkp]

Note that an appropriate metal raceway could provide the EGC path. But in your photo, the conduits and condulets appear to be PVC which is not an effective grounding path.

 

[kwired]

Technically speaking the ATS utility power 200A breaker IS a switch and would qualify to be used as an emergency disconnect per NEC.
However, Generac's warranty may disallow using theIr ATS in this manner. In this case I believe that the NEC would defer to their "follow the eqpt. Mfg. installation instructions" clause.
Makes for a lot more work for the electrician, and expense for the homeowner adding an a generator and ATS system.

If it is suitable for the service disconnect why wouldn't it be suitable for this new "emergency disconnect" now required by 2020 NEC? It still is a manual method of opening the supply from the downstream premises wiring. That breaker is a separate mechanism from the actual transfer switch which is automatically operated in normal mode, though Generac does have a handle to manually operate that, but no guarantees it won't automatically operate in either direction either just because you did use the manual lever.

 

[GarwoodV6]

If it is suitable for the service disconnect why wouldn't it be suitable for this new "emergency disconnect" now required by 2020 NEC? It still is a manual method of opening the supply from the downstream premises wiring. That breaker is a separate mechanism from the actual transfer switch which is automatically operated in normal mode, though Generac does have a handle to manually operate that, but no guarantees it won't automatically operate in either direction either just because you did use the manual lever.

See Fred B 's remarks above re: Generac (the ATS mfg.) precluding the use of their ATS without bonding the neutral and ground inside the ATS. Doesn't make them (Generac) right, but it sounds like they are forbidding use of the ATS as an emergency D/S, likely giving them the excuse to void their warranty responsibilities in the event of equipment failure if the neutral-ground bond strap was removed from the ATS.

 

[Tulsa Electrician]

One item to note.
I have been seeing some equipment come with a sticker and some not.
I take it as the equipment coming with the red sticker is listed for em disc. For me no red sticker no use.

 

[GarwoodV6]

One item to note.
I have been seeing some equipment come with a sticker and some not.
I take it as the equipment coming with the red sticker is listed for em disc. For me no red sticker no use.

What really matters is how you handle the ground and Neutral:
Bond the Neutral to the grounding system in it, and it becomes Service equipment and the main disconnect provided it is a Service Rated switch.
Isolate the Neutral and it becomes an "Emergency Disconnect" which makes the next downstream the Service Disconnect.

This permits the electrician adding an "Emergency Disconnect" or ATS to leave an existing system wired as-is *assuming it was already correctly wired* as the Service D/S Panel without having to split up the Neutrals and grounds.

My guess is this was the goal of the CMP in adding the "Emergency Disconnect" provision in the 2020 NEC.


Wiring an ATS as an "Emergency Disconnect" (isolated Neutral) also allows existing pre-1996 NEC 3-wire 120/240V branch circuits originating from the service Panel using the Neutral lead as an equipment ground (a la residential Range, Cooktop, Oven, and Dryer circuits) to still meet Code (via specific Code Exception) instead of forcing the existing "Service panel" to become a subfeed panel which would require isolated (unbonded) Neutrals and a separate ground lead run to the load, and splitting out all the grounds that were landed on the common Neutral/ground bus.

120/240V 2-conductor Branch circuits wired with NM or SE cable w/bare conductors serving as a Neutral would still need to be corrected, as using the bare ground as a neutral was never allowed -it was always required to be insulated and marked white.
As Larry Fine noted previously: some inspectors may permit bare conductors used as neutrals on 120/240V appliance circuits to be insulated in the service panel with white tape (or heat shrink tubing) as the AHJ. "Your mileage may vary".

 

[zooby]

In many cases the ATS will become the service disconnect. As long as it is service rated. And than that is where your grounding/bonding will take place.

Therefor making the inside panel a sub panel and requiring a 4 wire feeder.

But the 2020 NEC threw a wrench into what already confused people. But if understood correctly you can use to your advantage.

2020 code now requires an “emergency disconnect” outside of single family dwellings. And therefor if you identify your disconnect such as a meter main as your “emergency disconnect “ you bond neutral to case there and can continue your run to the house panel ( service disconnect) as service conductors only needing three wires. But the only downside to this is you now have to get your GEC into the house panel (service disconnect).

So many people myself included will label there meter main as both service disconnect and emergency disconnect as it’s much easier to keep the GEC outside and to cut down on length of it.

just trying to get my mind right...........so if the meter is "identified" as such, is power actually disconnected at this point in a -emergency- without the meter being pulled? Or is this an -emergency- where maybe the power company would be involved? Thanks!!

 

[Dsg319]

just trying to get my mind right...........so if the meter is "identified" as such, is power actually disconnected at this point in a -emergency- without the meter being pulled? Or is this an -emergency- where maybe the power company would be involved? Thanks!!

Alls the emergency disconnect is is a customer owned and bought disconnect outside the house that can be operated by anyone not needing to involve the power company.

 

[kwired]

What really matters is how you handle the ground and Neutral:
Bond the Neutral to the grounding system in it, and it becomes Service equipment and the main disconnect provided it is a Service Rated switch.
Isolate the Neutral and it becomes an "Emergency Disconnect" which makes the next downstream the Service Disconnect.

This permits the electrician adding an "Emergency Disconnect" or ATS to leave an existing system wired as-is *assuming it was already correctly wired* as the Service D/S Panel without having to split up the Neutrals and grounds.

My guess is this was the goal of the CMP in adding the "Emergency Disconnect" provision in the 2020 NEC.


Wiring an ATS as an "Emergency Disconnect" (isolated Neutral) also allows existing pre-1996 NEC 3-wire 120/240V branch circuits originating from the service Panel using the Neutral lead as an equipment ground (a la residential Range, Cooktop, Oven, and Dryer circuits) to still meet Code (via specific Code Exception) instead of forcing the existing "Service panel" to become a subfeed panel which would require isolated (unbonded) Neutrals and a separate ground lead run to the load, and splitting out all the grounds that were landed on the common Neutral/ground bus.

120/240V 2-conductor Branch circuits wired with NM or SE cable w/bare conductors serving as a Neutral would still need to be corrected, as using the bare ground as a neutral was never allowed -it was always required to be insulated and marked white.
As Larry Fine noted previously: some inspectors may permit bare conductors used as neutrals on 120/240V appliance circuits to be insulated in the service panel with white tape (or heat shrink tubing) as the AHJ. "Your mileage may vary".

Items on supply side of the service disconnect must be bonded to the grounded conductor as you have no EGC on supply side of service disconnect.

As is worded all you need is a switch, it doesn't have to contain overcurrent protection. It possibly can have overcurrent protection but if it does they have complicated this some as in past it would been deemed to be the service disconnect. The GEC can not be run to the second switch if it is not the service disconnect, but the GEC can be run to any point at or ahead of the service disconnect and up to the service drop/lateral conductors.

We have a rule that changes something in one part of code that also impacts things in another part that probably involves another CMP, coordinating each area well might not always happen first try with such changes.

 

[zooby]

Alls the emergency disconnect is is a customer owned and bought disconnect outside the house that can be operated by anyone not needing to involve the power company.

thanks much. reading too much into it.