How should an ETS work?

[ssandoval]

I have this issue come up on every new project; I can not see how an ETS wired into a fixture can work with a BAS. The wiring diagrams are fairly straightforward. It must have a constant hot, but it can simultaneously be switched. The argument I am having with the EC is that if the "constant hot" is routed through/ controlled by the BAS then it is no longer a constant hot. When the normal power circuit is shutdown at night by the BAS, the ETS senses a power loss and it transfers to the EM circuit, which is not hot because the main ATS is in normal power mode because there has been no loss of utility power. So, all of the EM lights and their LED's go off at night. With this in mind, I can't think of any reason (other than shortened life expectancy from overuse, which is definitely worth consideration) why it will not work this way, and our district no longer requires "night lights" in corridors and classrooms. However, in my opinion, the only way around this is to run a constant (normal power) hot to the ETS, by-passing the BAS, and then run the BAS-controlled circuit to the ETS for the "switched" power source. The object is to be able to shut off all of the lighting in the bldg. at night for energy conservation. In order to accomplish this, am I correct in assuming that a "constant hot" non-BAS controlled circuit will now have to be run to EVERY emegency light?

Any thoughts or suggestions would be appreciated.

 

[iwire]

If you run back up batteries down every night, the batteries and / or chargers will be junk in short time. They need a constant hot that is in fact constant until the utility fails.

 

[ssandoval]

If you run back up batteries down every night, the batteries and / or chargers will be junk in short time. They need a constant hot that is in fact constant until the utility fails.

No backup batteries here; the ETS is installed so that when utility (normal) power is lost it auto senses and switches over to the EM circuit. In the past, we did not need them because the EM lights just burned all the time and when the ATS transfered they ran on generator/ EM power.

Because of the energy code and the push for "greener" bldgs, we no longer allow "night lights" to be used. Hence the need for the ETS. My problem is that the MEP folks were pretty vague on the drawings and didn't realize that the "constant hot" was actually being shut off by the BAS.

 

[iwire]

No backup batteries here; the ETS is installed so that when utility (normal) power is lost it auto senses and switches over to the EM circuit. In the past, we did not need them because the EM lights just burned all the time and when the ATS transfered they ran on generator/ EM power.

Oh I thought you had some battery backed up ballasts.

it transfers to the EM circuit, which is not hot because the main ATS is in normal power mode because there has been no loss of utility power.

I don't understand this arrangement at all.

 

[Electric-Light]

You kill the power to fixture to turn off the light. You don't need unswitched hot unless you have emergency ballasts.

 

[ssandoval]

You kill the power to fixture to turn off the light. You don't need unswitched hot unless you have emergency ballasts.

You have to have the unswitched constant hot because that's how the ETS senses power loss and transfers...

The fixture can be switched on/off but this is done through a different set of leads.

 

[markstg]

You have to have the unswitched constant hot because that's how the ETS senses power loss and transfers...

The fixture can be switched on/off but this is done through a different set of leads.

If you are talking about the ETS like Iota Engineering makes

http://www.iotaengineering.com/emlib/cutsheets/etsspec.pdf

You are correct. 3 Hots are run to the ETS
1 Hot all the time, right off the branch circuit breaker
2 A switch leg hot that goes on and off by a the BAS and/or a light switch
3 Generator Hot that is only hot when the generator is running and the ATS has transferred the load to the Emergency Source (generator)

Normally the generator hot is NOT HOT, and the fixture goes on/off with the switch leg hot from the BAS and/or light switch. When normal power (utility) is lost the hot all the time wire at the ETS losses power, and when the EG gets power to the ETS it sends the power to the fixture. Since there are no batteries, the light is off between loss of utility power and EG coming online and ATS switching....neat.