Neutral used with Emergency CKT. Interface

[dpenbert]

I am working with a design that calls for an Emergency Circuit Interface (ECI) module that switches power from normal to emergency when the normal power goes out. The normal power has a derived system that consists of one hot a neutral and a ground. The normal power feeds normal lighting and feeds emergency lighting via the ECI module. Emergency power has a seperately derived system that obtains power from a generator. So the ECI module essentially works like a transfer switch.

The ECI module manufacturer sent me a diagram that shows a connection between the normal power neutral and the emergency power neutral and a tap from that connection to the ECI module. One neutral wire will go to the emergency lights, a neutral which is connected to both emergency and normal neutrals.

For applications such as this I am used to providing a double-pole-double-throw relay that will use normal power and normal neutral under normal conditions and will switch to emergency power and emergency neutral in case of loss of power.

Can a bond between the two neutrals allow the system to work properly?

Thanks
---------------
David

 

[dpenbert]

Re: Neutral used with Emergency CKT. Interface

Also, in this case, I believe we have a separately derived system because the emergency power comes from the transformer secondary (the primary is supplied by the generator - which is not separately derived).

The neutrals at the ECI module are not switched, they are solidly connected together as I described in the last thread.

To simplify the question, can you solidly connect the neutrals of two separately derived systems in a "transfer switch"?


Thanks
-------------
David