Emergency Lighting Via Generator Only

[Npstewart]

Good afternoon,

We conducted a site visit at a large building that is equipped with two services. One service (Service #1) is effectively 2000A @ 480/3. The other service, (Service #2) is approximately 150A @ 480/3. Service #2 is backed up with a ATS and 75 kW generator.

The whole purpose of this service #2 is to feed lights throughout the building which are lit 24/7, and are NOT equipped with any switches. Basically, the lights are always on, and if the power goes out, the generator will start (Hopefully after 10 seconds) and these lights will continue to be illuminated. This generator also feeds a couple other items such as a large IT closet.

Does anyone see any issues with this installation assuming that all areas that require emergency lights have a fixture? Keep in mind, this was built under the NEC 1990.

I see a couple problems but not sure how it relates to codes

#1. The lights burn all the time, and most of them were burnt out.
#2. It takes 10-15 seconds for a good ATS to start depending on different conditions.
#3. There is no redundancy to this system. If the generator fails, none of the lights will come on. Typically, even if 20% of typical battery backup fixtures fail, you can still make your way out of the building.

Thanks!

 

[iwire]

A couple of quick points

We do a ton of generators and being able to start in 10 seconds is not a problem

Next it sounds like it is a standby generator as it supplies IT equipment. That is an issue.

 

[Npstewart]

Why do you think the IT equipment would be an issue? I know it is an issue if this was a healthcare facility/hospital because the equipment branch has to be separate from the life-safety branch. Do you have a code reference for a general purpose building though?



Thanks for your input.

 

[charlie b]

The problem is that emergency systems cannot be shared with optional standby systems. They have to have separate transfer switches. Reference 700.6(D).

 

[Npstewart]

I wonder if this was the case with the 1990 NEC? I have a copy of 1993, probably the same.

 

[MIEngineer]

The fact that the lamps are burnt out is a maintenance issue no different than testing the batteries in the emergency fixtures. While the generator not starting is a concern the code still allows this without any batteries required in the building. I have had different consultants propose batteries on the exit signs or an inverter system for the lighting along with the generator.

I don't know about code compliance but our facilities from that time frame and earlier all have a combined legally required and standby loads on a single ATS.

 

[Npstewart]

In my NFPA 70 - 1996, it only says "Transfer equipment, including automatic transfer switches, shall be automatic and identified for emergency use and approved by the AHJ." I think per the 2008 NEC it would be illegal to serve other equipment using the same transfer switch for equipment as for the egress lighting, but in 1990 it was probably legal.

 

[hillbilly1]

Emergency lighting can be switched, but must have an automatic means of turning on upon power failure. This is usually accomplished by electrically held N/C contactors. The coil on the contactor is feed by the normal power source for area lighting, in which upon failure drops out the contactor, closing the contacts. This is a cheap and easy way to save $$$ on electricity and maintaince in a large building if the lights do not need to be on during non-occupied hours.