ChasM
Member
- Location
- North Texas
- Occupation
- Retired. Electrical System engineer/simulator architect
I understand that NEC 230.85 now requires an emergency disconnect switch (EDS) to be installed on the outside of a house so emergency responders can remove all electrical power from the building. The house is supplied with a 120/240V, 200A split phase electrical service (L1, L2, and N).
However, this requirement becomes somewhat of an enigma when there is a generator with an automatic transfer switch (ATS) at the house with an auto-start capability when utility power is lost. In this situation the generator would immediately try to autostart when the emergency responder opens the emergency disconnect switch, thus energizing the house electrical systems. Not a good situations!
I would like to configure an approach where the emergency responder action does not cause thr generator to autostart. I see several possibilities and would like some feedback back on my preferred solution.
1. Add a second emergency disconnect switch for the generator next to the unity servcoe switch - Not a good situation since the emergency responder must open two switches to remove all power from thr house.
2. Connect the EDS between the house electrical panel and the house output from the ATS - Not a good solution since the ATS and the generator remain have full electrical power with thr house circuits isolated.
3. Preferred approach - Make use of the Generac remote start feature by running the two remote start control wires through the third pole/blade of the EDS. In normal operation, when the EDS is normally closed the generator will automatically startup and power thr house when utility power is lost. When the EDS is opened by an emergency responder, the generator autostart function is disabled preventing the generator from starting and all power is removed from the house by a single emergency responder action. This appears to be the correct solution however does the 2020 NEC allow control wiring to be rooted through one of the poles of a three pole EDS.
I would appreciate any comments on my house requirement so the emergency responder is protected in the best manner possible.
However, this requirement becomes somewhat of an enigma when there is a generator with an automatic transfer switch (ATS) at the house with an auto-start capability when utility power is lost. In this situation the generator would immediately try to autostart when the emergency responder opens the emergency disconnect switch, thus energizing the house electrical systems. Not a good situations!
I would like to configure an approach where the emergency responder action does not cause thr generator to autostart. I see several possibilities and would like some feedback back on my preferred solution.
1. Add a second emergency disconnect switch for the generator next to the unity servcoe switch - Not a good situation since the emergency responder must open two switches to remove all power from thr house.
2. Connect the EDS between the house electrical panel and the house output from the ATS - Not a good solution since the ATS and the generator remain have full electrical power with thr house circuits isolated.
3. Preferred approach - Make use of the Generac remote start feature by running the two remote start control wires through the third pole/blade of the EDS. In normal operation, when the EDS is normally closed the generator will automatically startup and power thr house when utility power is lost. When the EDS is opened by an emergency responder, the generator autostart function is disabled preventing the generator from starting and all power is removed from the house by a single emergency responder action. This appears to be the correct solution however does the 2020 NEC allow control wiring to be rooted through one of the poles of a three pole EDS.
I would appreciate any comments on my house requirement so the emergency responder is protected in the best manner possible.