Multiple circuits in a linear lighting fixture

[dunbarx]

A local inspector (in Los Angeles) has flagged one of our ceiling mounted LED linear lighting fixtures. It is comprised of several separate sections joined end to end to create a single long finished fixture. Each section has its own LED driver and LED array.

Mains power enters this assembly from one end, and is bussed through each section all the way to the other end. Another separate building generator circuit (for emergency lighting during a power failure) enters a single interior section within the whole. That section contains two drivers, one for normal operation, and one for emergency operation.

The inspector asserts that the NEC does not allow such a configuration, that the main power bus cannot pass through the interior “emergency" section at all. He says that we must have three separate power feeds, one to the emergency section, and one each to the group of sections on either side of that emergency section.

Is this limitation is in fact true?

Thank you for any clarification.

Craig Newman

 

[augie47]

As far as the fixtures are concerned, 410.64 seems to permit that method.
If it's truly an emergency circuit it appears 700.10 would not allow that arrangement.

 

[acrwc10]

As far as the fixtures are concerned, 410.64 seems to permit that method.
If it's truly an emergency circuit it appears 700.10 would not allow that arrangement.

the key word being "emergency", is it a back up circuit or an emergency circuit.

 

[tom baker]

Emergency as from an Art 700 source. Or is it a 701 legally required standby source?

 

[dunbarx]

I do not know the difference between "backup" and "emergency". This is to give light during a power outage, to allow occupants to find their way to the exit. In the lighting world, this is called "emergency" (EM) backup lighting.

 

[augie47]

The inspector should be able to tell you ( the determination is often a governmental call) plus the Code Section he's enforcing will help.
Until you know that, no determination on acceptability can be made.
(What is the nature of the building ?)

 

[infinity]

The inspector asserts that the NEC does not allow such a configuration, that the main power bus cannot pass through the interior “emergency" section at all. He says that we must have three separate power feeds, one to the emergency section, and one each to the group of sections on either side of that emergency section.

If the emergency part of the fixutre is being used for egress lighting powered by the generator during a power failure then I agree with the inspector.

 

[tom baker]

What is the source of power to the elight? Generator, inverter, or regular power panel?
Does the elight have its own battery back up?

 

[tom baker]

I do not know the difference between "backup" and "emergency". This is to give light during a power outage, to allow occupants to find their way to the exit. In the lighting world, this is called "emergency" (EM) backup lighting.

Yes, agreed. And the NEC (our world) has an article on emergency sources of power, which it where the rules for your elights are

 

[dunbarx]

@tom baker. The power source for the section in question is "generator". Though we use local battery powered EM power packs as well, when building generator power circuits are specified, we do not.

@augie47. I will try to get the code section.

And thank you all for this feedback. This is a wonderful forum.

 

[steve66]

As far as the fixtures are concerned, 410.64 seems to permit that method.
If it's truly an emergency circuit it appears 700.10 would not allow that arrangement.

What about 700.10 Exception #2? "Wiring supplied from 2 sources in exit or emergency luminaries."

Edit; The more I look at that paragraph, the more confused I am.

Also, is the normal power "bussed" through the EM fixture, or wired? And are you sure there isn't any separation between the EM wiring and the "normal" wiring?

 

[dunbarx]

@steve66. I do not know the difference between "bussed" and "wired:. I apologize, but we are not electricians. Perhaps we should be.

The mains power feed enters a section at one end and continues through each section in turn. It is three 12 AWG wires (Black, white and green) that are passed via connectors from one section to the next. We call that a "bus" and tap into it in each section to supply power to the section LED driver .

In the interior "emergency" section, that bus simply is not tapped. It passes through intact to the next section. A separate generator-connected power feed enters that section.

 

[infinity]

In the interior "emergency" section, that bus simply is not tapped. It passes through intact to the next section. A separate generator-connected power feed enters that section.

That is what seems to be the issue. You have normal conductors run through the same fixture with the EM conductors.

 

[tom baker]

A solution would be to install a battery backed up emergency light in the section in question and remove the emergency wiring from the generator

 

[infinity]

A solution would be to install a battery backed up emergency light in the section in question and remove the emergency wiring from the generator

That would work but if I owned the building I wouldn't want that.

 

[dunbarx]

Would creating a separate "raceway", perhaps a linear metal barrier the length of the emergency section, be considered as something that "legally" separates the two circuits from each other? We certainly could do this outside that section, jumping over with a length of Greenfield. Could it be done internally?

 

[tom baker]

Would creating a separate "raceway", perhaps a linear metal barrier the length of the emergency section, be considered as something that "legally" separates the two circuits from each other? We certainly could do this outside that section, jumping over with a length of Greenfield. Could it be done internally?

You get into UL listing issues, could be done but inspector may not approve

 

[Strathead]

Yeah! This is one that I am solid in. I am dealing with this issue up front because I became educated on my last job. So, 700.10 exception #2 is part of the answer, but..... The other part is the fixture needs to be listed as an Emergency fixture. That is a UL 924 listing for the linear fixtures. I assume this assures the wiring is in compliance with other manufacturing requirements for the separation. Finelite HP4's carry this listing. They have a UL compliance officer and can readily supply you with the education I have on this subject, along with the listing of the fixture. HE Williams MX4R does not currently carry this listing, but they will have it within a few weeks. They are new to this fixture market and weren't aware until I asked my Rep to get the letter from them certifying that the fixture was properly listed, before AHCA inspected my job. I wonder how many of these have been installed without this listing. I don't know about Acuity Brands at this time. If yours are Acuity, come back and tell us.

 

[suemarkp]

I do not know the difference between "backup" and "emergency". This is to give light during a power outage, to allow occupants to find their way to the exit. In the lighting world, this is called "emergency" (EM) backup lighting.

You didn't really say at the beginning if this is in your facility, or you make a product for others and when it was installed it got flagged. Regardless, you need to understand the use of the word "emergency" when talking to an electrical inspector. Backup power systems can be optional (NEC 702), legally required (NEC 701), or emergency (NEC 700).

Your house would be an optional system. You choose to have a generator and there are no requirements of what has to be powered -- its what you want. A restaurant with seating for 100+ of people would most likely require an "emergency system".

Emergency systems are required in certain buildings by the municipality or a government agency. This provides power for life safety and covers egress and exit lighting. Here is an informational note from the NEC as to what these systems are:

Informational Note: Emergency systems are generally installed in places of assembly where artificial illumination is required for safe exiting and for panic control in buildings subject to occupancy by large numbers of persons, such as hotels, theaters, sports arenas, health care facilities, and​

similar institutions. Emergency systems may also provide power for such functions as ventilation where essential to maintain life, fire detection and alarm systems, elevators, fire pumps, public safety communications systems, industrial processes where current interruption would produce serious life safety or health hazards, and similar functions.​

If this is a light fixture you chose to have on backup power, don't call it an emergency system. If OSHA or someone requires this to be an "emergency system", there are rules to be followed in NEC 700. A key one is keeping all wiring from the emergency system separate from non-emergency wiring. Mixing emergency and non-emergency in a common conduit or a gutter (e.g. light fixture) is not allowed. But like everything in the NEC, there are exceptions.

 

[dunbarx]

@suemarkp.

This is for a commercial installation, flagged by a local inspector. As I posted earlier, this is occupant exit lighting (backup, I now understand, and as you say) during a power failure. Again, it is common in the lighting world to label these sorts of fixtures as "emergency" lighting. I have learned here that this term is fraught with peril.

This thread is a pretty good primer. I appreciate the time all have spent on this for me.