Interlock kits in parallel

[kwired]

That's interesting. I'm going to ask the city inspector when I see him. He used to do a lot of hospital work before becoming the EI. To answer Augie's question it is a 9 or10kw portable generator.

Why not just go to art 517 and do a little reading - here is one place that makes it clear that more then one transfer switch may be needed at times:

517.30(B)(2) Transfer Switches

The number of transfer switches to be used shall be based on reliability, design, and load considerations. Each branch of the essential electrical system shall have one or more transfer switches. One transfer switch and downstream distribution system shall be permitted to serve one or more branches in a facility with a maximum demand on the essential electrical system of 150 kVA.


Illustrations that follow that section even show a one line diagram of this.

 

[GerryB]

Why not just go to art 517 and do a little reading - here is one place that makes it clear that more then one transfer switch may be needed at times:

517.30(B)(2) Transfer Switches

The number of transfer switches to be used shall be based on reliability, design, and load considerations. Each branch of the essential electrical system shall have one or more transfer switches. One transfer switch and downstream distribution system shall be permitted to serve one or more branches in a facility with a maximum demand on the essential electrical system of 150 kVA.


Illustrations that follow that section even show a one line diagram of this.

OK. I read it. My 05 code handbook has a note about a single transfer switch that says "based on the assumption that the transfer switch has sufficient capacity to handle the combined loads and that the alternate source of power is sufficiently large to withstand the impact of the simultaneous transfer of both systems in the event of a normal power loss" I was curious about the word "reliability", if something is "designed" for the load you would think it to be reliable.

 

[kwired]

OK. I read it. My 05 code handbook has a note about a single transfer switch that says "based on the assumption that the transfer switch has sufficient capacity to handle the combined loads and that the alternate source of power is sufficiently large to withstand the impact of the simultaneous transfer of both systems in the event of a normal power loss" I was curious about the word "reliability", if something is "designed" for the load you would think it to be reliable.

If you got that out of the handbook commentary remember it is only the authors opinion and not an official NFPA interpretation of any NEC content.