Branch Circuit Transfer Switching 1

[Senselessticker]

Forgive me if I sound ignorant (I'm a new EE fresh out of school). Is it "unconventional" or a code violation to place a transfer switch on the load side of a branch circuit breaker of a lighting panel to supply the branch with alternate power (from a generator)?

 

[rbulsara]

Yes it is unconventional if you are using generator as 'emergency power source' but not a Code violation assuming you are using equipment listed and rated for such use.

If you are looking for guidance to a specific task, you need to post more details as to what you are trying to acheive.

In fact, for self-contained emergecny lighting units (with battery and charger), each unit contains a trasfer relay which amounts a transfer switch on load side of the branch circuit. This is different than using generator as emergency source.

 

[cuky2000]

The primarily function of the transfer switch is to isolate the normal main feed from the backup power source. If understood well, the propose connection appear to fail isolatin the normal power source. Please clarify.

Special attention should be given to the transfer switch-grounding requirement. Please see the enclose sites.

http://www.energy.ca.gov/distgen/interconnection/equipment.html

http://www.ecmweb.com/mag/electric_grounding_onsite_power/

 

[Senselessticker]

Thank you both for your replies. I should have been more specific.

1. I should have stated that the switch is to be a manual switch not an ATS.

2. The generator is in fact an emergency generator, but my client is trying to upgrade the emergency lighting so that E-lights do not depend on the generator but CAN be switched over (manually) to be powered by the generator in cases of extented building outage (let say, for maintenance).

3. The building is old (completed in early 1950's). There are a number of designated emergency panels, each having its own ATS to switch to "emergency power".

The "non-emergency" panels in the building do not have shunt trip breakers. And I need to power specific branch circuits (like circuits that have battery backed E-lights on them) by switching manually to the generator.

The main idea being that if a power failure occurs the emergency lights will switch to battery mode be it a fluorescent emergency ballast, or wall mounted "aimable" battery power light. Then, if it is desired, someone can manually switch the lights to generator power (and the e-light batteries will be charging even though the normal power is out). BUT, I cannot power an entire lighting panel, but only want to power few of the branches. I hope this is more clear. Thanks.

 

[rbulsara]

Well...since you can only connnect one circuit to a MTS, you will need as many MTS as the E-branch circuits, This will not be a most cost effective or practical solution.

One MTS and feeding a 'emergency' panel could be the best soultion, imho. You will have to wire the individual emergency circuits to this panel.

 

[mpparent]

If I'm not mistaken, if you are actually powering EMERGENCY lighting for EGRESS purposes eg Life Safety issues, then shouldn't the transfer switch be automatic? I agree that the easiest solution would be to install a new panelboard, fed via an ATS, and intercept and extend the branch circuits you want to this new panel.

Mike

 

[peebee]

I'm more concerned that you would be restoring power to your unit-battery emergency lighting fixtures, which would extinguish the lamps at those fixtures, while your normal lighting power was still de-energized. . . .

 

[Senselessticker]

I am aware that the battery unit lights will turn "off". And I know all this seems a little strange. However, all that I really need to know is if it is voilation of code to install a manual transfer switch from a branch circuit (that contains emergency lighting) to an alternate power source. This switch would tie the branch to a different panel.

Thanks to everyone for their input.

 

[robertb]

Please consider the following:
Per Article 5-10.3.5 of NFPA 101-1997 (Life Safety Code) “…the exit signs shall be illuminated by the emergency lighting facilities.”
Article 5-9.1.2 of Section 5.9 (Emergency Lighting) of NFPA 101 states that “Where emergency lighting is provided by a prime-mover operated electric generator, a delay of not more than 10 seconds shall be permitted.”