Re: service disconnect for stanby system
Originally posted by benwieland:
i dont need to set a service disconnect between the meter and the ats -- do i ---the main panel is directly on the other side of the wall.
It is a code violation to install a transfer switch ahead of the service disconnect.
230.82 Equipment Connected to the Supply Side of Service Disconnect.
Only the following equipment shall be permitted to be connected to the supply side of the service disconnecting means:
(1)Cable limiters or other current-limiting devices.
(2)Meters, meter sockets, or meter disconnect switches nominally rated not in excess of 600 volts, provided all metal housings and service enclosures are grounded.
(3)Instrument transformers (current and voltage), high-impedance shunts, load management devices, and surge arresters.
(4)Taps used only to supply load management devices, circuits for standby power systems, fire pump equipment, and fire and sprinkler alarms, if provided with service equipment and installed in accordance with requirements for service-entrance conductors.
(5)Solar photovoltaic systems, fuel cell systems, or interconnected electric power production sources.
(6)Control circuits for power-operable service disconnecting means, if suitable overcurrent protection and disconnecting means are provided.
(7)Ground-fault protection systems where installed as part of listed equipment, if suitable overcurrent protection and disconnecting means are provided.
Notice transfer switches are not in the list.
This is why a transfer switch used in the manner you want to must be rated as service equipment and that will add significantly to the cost of the switch.
A service rated transfer switch must have an external manual means to disconnect both the utility and generator power from the building.
Also if you did this the service disconnect has now been relocated outside to the ATS and the indoor panel will have to have the neutrals and grounds isolated from each other.
An equipment grounding conductor will need to be run into the 200 amp panel from the ATS.
Any grounding electrode conductors will have to be moved from the 200 amp panel out to the ATS.
As tx2step pointed out the generator capacity vs the service size seems to be a problem also.
Can I make a suggestion?
Forget the original plan, which would require an expensive 200 amp service rated ATS, all the EGC, GEC work and would probably trip the generators main when the ATS switches.
Use a standard 100 amp ATS mounted inside beside the existing panel and feed a 100 amp MLO panel beside that. Run a large raceway between the existing 200 amp panel and the new 100 amp sub panel and move the circuits over to the 100 amp sub panel that the customer needs to run on the generator.
The code allows 'overloading' an optional generator (in a way) however it makes little sense to do so with an ATS.
[ June 17, 2005, 02:49 PM: Message edited by: iwire ]