Generator

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paul renshaw

paul renshaw

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Location
Cordova, Maryland
Existing set up:
400amp 3ph 120/208 feeder to transfer switch Normal Source Terminals from switchgear.
400amp 3ph 120/208 feeder to transfer switch Emergency Source Terminals from Generator, breaker at generator.
400amp 3ph 120/208 feeder to remote panel from transfer switch Load Terminals, wires go into a trough and leave via conduit to panel.
Is it legal to tap the load conductors of the xfer switch that run from the xfer switch Load Terminals to the panel board, go into a breaker and can or fused disconnect, and feed another smaller panel to add some items to the emergency power set up? The total load on the panels does not even come up to half the generator capacity, so load is not an issue. I am discussing this with an engineer and there are different opinions. Please cite code refs to verify legality or not within NEC rules. (2014)
 
First question I would ask (and I am now asking it) is whether any of the loads supplied are anything but "optional standby", regardless of the " emergency source" labelling at the ATS.
I suspect not, but let's get that clear first.

Tapatalk!
 
The first thing we need to know is if the transfer switch is really an article 700 emergency transfer switch or is it a article 701 legally required transfer switch or an article 702 optional standby transfer switch.

That has to figured out.

Once that is figured out we need to know if you want to add emergency, legally required or optional loads to it.


What I am getting to is that if it is really an emergency transfer switch you may have to add a transfer switch to add other types of loads.
 
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It currently supplies an IT room. The panel fed from the xfer switch is in the IT room and only the equipment in that room is fed out of the panel, including two ductless split system units for the HVAC. No branch circuits from the panel leave the room.
 
Just got a look at the Genset today, and will check over the xfer switch tomorrow as it is remotely located in the building. 150 KVA with about 40-45 amps load on each phase.
 
paul renshaw said:
Existing set up:
400amp 3ph 120/208 feeder to transfer switch Normal Source Terminals from switchgear.
400amp 3ph 120/208 feeder to transfer switch Emergency Source Terminals from Generator, breaker at generator.
400amp 3ph 120/208 feeder to remote panel from transfer switch Load Terminals, wires go into a trough and leave via conduit to panel.
Is it legal to tap the load conductors of the xfer switch that run from the xfer switch Load Terminals to the panel board, go into a breaker and can or fused disconnect, and feed another smaller panel to add some items to the emergency power set up? The total load on the panels does not even come up to half the generator capacity, so load is not an issue. I am discussing this with an engineer and there are different opinions. Please cite code refs to verify legality or not within NEC rules. (2014)
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If this transfer switch feeds non-emergency loads, and your goal is for it to serve emergency loads, you will need a separate transfer switch to do so. One switch cannot provide power to both emergency (Article 700) and non-emergency (Article 701 & 702) loads. See 700.5(D).
 
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