EM Fixtures

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JES2727

Senior Member
Location
NJ
So with an Art. 700 installation the lights can be dark for up to 10 seconds until the generator takes over. In an Art. 702 installation the lights will remain lit, on battery power, until the generator takes over. Is that correct? And the reason for this is because the exit/egress lights cannot rely on the performance of an optional stand-by system. It makes sense, I suppose, but at first glance it seems a little bass ackwards.
 

ron

Senior Member
So with an Art. 700 installation the lights can be dark for up to 10 seconds until the generator takes over. In an Art. 702 installation the lights will remain lit, on battery power, until the generator takes over. Is that correct? And the reason for this is because the exit/egress lights cannot rely on the performance of an optional stand-by system. It makes sense, I suppose, but at first glance it seems a little bass ackwards.
I agree.

You have a choice.
 

iwire

Moderator
Staff member
Location
Massachusetts
I don't understand why batterieds are needed if they are feed from an EM source? Aren't batteries required where the lights are feed from a normal source so they stay lit?
Because it does not appear you have an 'EM' source, you have an 'Optional Standby' source and optional standby sources do not qualify to supply emergency lighting.

There is a lot to this and for sake of keep it short I will generalize.

An Emergency Generator as covered by Article 700 can only supply loads that the AHJ determines are true emergency loads, like egress lighting. It cannot (normally) supply HVAC units, coffee makers or even the telephone equipment.

All the wiring between the load and the emergency generator must be kept entirely separate from other wiring. No sharing raceways, panels, transfer switches, junction boxes (there are some exceptions) This adds a lot of work and equipment. The emergency circuits are treated like they are sacred.


On the other hand

An Optional standby generator can supply whatever loads the designer wants except emergency loads. An optional standby generator cannot directly supply emergency lighting.

With optional systems the wiring can be mixed in the same conduits and raceways as other wiring.

So you mentioned that this circuit starts at a panel that supplies other loads like HVAC units. This very strongly suggests you are dealing with an optional standby generator and that being the case it cannot be used to directly supply emergency lighting.

In this case the battery units happen to take care of the emergency lighting requirements, but the designer also decided to take advantage of the generator on site. Now during a power failure the battery takes over and if the standby generator does run as it should it will power up the fixture and recharge the battery unit. However if the standby fails you will still have the required emergcny lighting.
 
T

T.M.Haja Sahib

Guest
What is the difference between a standby or em genset?:? THanks.
It is a matter of duration of changeover from No Power Supply from Power company to genset Power Supply that differntiates an em genset from stansby genset.
 

pete m.

Senior Member
Location
Ohio
Because it does not appear you have an 'EM' source, you have an 'Optional Standby' source and optional standby sources do not qualify to supply emergency lighting.

There is a lot to this and for sake of keep it short I will generalize.

An Emergency Generator as covered by Article 700 can only supply loads that the AHJ determines are true emergency loads, like egress lighting. It cannot (normally) supply HVAC units, coffee makers or even the telephone equipment.

All the wiring between the load and the emergency generator must be kept entirely separate from other wiring. No sharing raceways, panels, transfer switches, junction boxes (there are some exceptions) This adds a lot of work and equipment. The emergency circuits are treated like they are sacred.


On the other hand

An Optional standby generator can supply whatever loads the designer wants except emergency loads. An optional standby generator cannot directly supply emergency lighting.

With optional systems the wiring can be mixed in the same conduits and raceways as other wiring.

So you mentioned that this circuit starts at a panel that supplies other loads like HVAC units. This very strongly suggests you are dealing with an optional standby generator and that being the case it cannot be used to directly supply emergency lighting.

In this case the battery units happen to take care of the emergency lighting requirements, but the designer also decided to take advantage of the generator on site. Now during a power failure the battery takes over and if the standby generator does run as it should it will power up the fixture and recharge the battery unit. However if the standby fails you will still have the required emergcny lighting.
I agree. Thanks for the clear explanation.

Pete
 

horsegoer

Senior Member
Location
NJ
Because it does not appear you have an 'EM' source, you have an 'Optional Standby' source and optional standby sources do not qualify to supply emergency lighting.

There is a lot to this and for sake of keep it short I will generalize.

An Emergency Generator as covered by Article 700 can only supply loads that the AHJ determines are true emergency loads, like egress lighting. It cannot (normally) supply HVAC units, coffee makers or even the telephone equipment.

All the wiring between the load and the emergency generator must be kept entirely separate from other wiring. No sharing raceways, panels, transfer switches, junction boxes (there are some exceptions) This adds a lot of work and equipment. The emergency circuits are treated like they are sacred.


On the other hand

An Optional standby generator can supply whatever loads the designer wants except emergency loads. An optional standby generator cannot directly supply emergency lighting.

With optional systems the wiring can be mixed in the same conduits and raceways as other wiring.

So you mentioned that this circuit starts at a panel that supplies other loads like HVAC units. This very strongly suggests you are dealing with an optional standby generator and that being the case it cannot be used to directly supply emergency lighting.

In this case the battery units happen to take care of the emergency lighting requirements, but the designer also decided to take advantage of the generator on site. Now during a power failure the battery takes over and if the standby generator does run as it should it will power up the fixture and recharge the battery unit. However if the standby fails you will still have the required emergcny lighting.
Great Explanation!!!!!! THanks.
 

horsegoer

Senior Member
Location
NJ
So can you have the scenario where it is a "Optional Standby GEnerator System" but the spec say to keep em circuits separate? But just so I am clear, if it is an OSGS you can mix em/norm circuits in same raceway by code? Thanks.

Oh one other thing. How does someone confirm whether it is a 700 or 702 design? THanks again.
 

horsegoer

Senior Member
Location
NJ
Sorry one other question. If it is a 702 design and the EM lights are fed from the generator they don't HAVE to have battery pack, correct? Is a EM ballast and battery pack the same thing?:ashamed1:
 

horsegoer

Senior Member
Location
NJ
You seem to have some odd specs, the only one that can really tell you what the design is about would be the designer.
No my specs don't say that, I was just curious. It seems that if it was a 702 design you would not have a spec that said to keep em circuits separate. But isn't it essential to know if it is 700 or 702 design during the bidding process so you know whether or not you can combine em/norm circuits.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
No my specs don't say that, I was just curious. It seems that if it was a 702 design you would not have a spec that said to keep em circuits separate. But isn't it essential to know if it is 700 or 702 design during the bidding process so you know whether or not you can combine em/norm circuits.
Since you're in NYC I would guess that this is a 700 system not a 702. Ultimately you would need to ask the designer what type of system you have.
 

horsegoer

Senior Member
Location
NJ
Since you're in NYC I would guess that this is a 700 system not a 702. Ultimately you would need to ask the designer what type of system you have.
Sorry to keep pounding this topic. But id the em panels feed hvac loads etc. isn't that not considered life safetey/critical loads as stated earlier and it would not be a 700 design? Thanks.
 

stevegw

Member
You still need em ballasts because the gen wont kick in unless the power goes out to the whole building but you might lose power to 1 section. If the power was out in just a stairway or other small area it could be dangerous to the occupants trying to get out.
 

horsegoer

Senior Member
Location
NJ
You still need em ballasts because the gen wont kick in unless the power goes out to the whole building but you might lose power to 1 section. If the power was out in just a stairway or other small area it could be dangerous to the occupants trying to get out.
I don't understand. If power goes out for to a panel feed by the genset the ATS will switch over and the genset will kick in.
 

ron

Senior Member
You still need em ballasts because the gen wont kick in unless the power goes out to the whole building but you might lose power to 1 section. If the power was out in just a stairway or other small area it could be dangerous to the occupants trying to get out.
The code does not require this. The fact that a localized outage in the building (not the entire building) will not start the generator, is just a downside of that design, but does not require localized em battery ballasts.
 
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