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    Lighting on Generator

    I am struggling with the statement in 700.17 "Unless both ....are kept lighted."

    The entire building is being put onto generator and night lights are not requested. If I did put in battery powered lights, they would never come on - or would only come on for the few seconds while the generator was starting. What am I missing here? Am I required to have night lights in order to put the whole building on generator? This is a partially attended greenhouse facility. But I am curious in general due to the wording.

    If the building had partial generator power, then either I would provide a GTD device for emergency lighting or I would provide ballasts or emergency heads. But if the whole building is on generator, there is no panel to get a signal telling the fixtures that the building is on emergency. So any provided emergency fixtures would seldom be on and then only for seconds.

    So where is the exclusion to "are kept lighted"?

    #2
    Asked another way

    This appears to be a place where the NEC is not expressing the situation according to common practice. It appears to me that article 700 requires lighting that will come on automatically in the case of an emergency. Devices exist that will turn on the lights when the load is on emergency, however, these devices require a signal from a normal power panel. If the whole building is on an emergency generator, then there is no normal power panel and therefore there is no simple way to cause this to happen. Further, any battery powered lights would also not come on. There are -IMHO crazy- ways to make the lights come on by using the position indication in the transfer switch - but really? Is there any possible reason for doing this?

    And so - I imagine I am wrapped up in semantics - not for the first time. I tend to read very literally. But does nobody have any curiosity or opinion on this?

    Comment


      #3
      Originally posted by dema View Post
      This appears to be a place where the NEC is not expressing the situation according to common practice. It appears to me that article 700 requires lighting that will come on automatically in the case of an emergency. Devices exist that will turn on the lights when the load is on emergency, however, these devices require a signal from a normal power panel. If the whole building is on an emergency generator, then there is no normal power panel and therefore there is no simple way to cause this to happen. Further, any battery powered lights would also not come on. There are -IMHO crazy- ways to make the lights come on by using the position indication in the transfer switch - but really? Is there any possible reason for doing this?

      And so - I imagine I am wrapped up in semantics - not for the first time. I tend to read very literally. But does nobody have any curiosity or opinion on this?
      The system you are describing is an Article 702, Optional Standby System and not suitable to be used for emergency lighting. You must comply with all the applicable sections of Article 700 to supply emergency lighting. You can have both 700 and 702 systems in the same building, even supplied from the same genset (assuming the genset complies with NFPA 110) but there are a number of design factors to consider. For starters, you will need separate ATSs for each system in addition to a number of other requirements.
      Often in a smaller building and you just need emergency lighting it is advantageous to just use unit equipment for the lighting even though you have a generator.

      Comment


        #4
        702 and thank you

        You have totally answered what I NEED to know - I was looking in 700 instead of 702 and 702 applies. And 702 does not discuss the lighting in the same way. The generator is big enough for the whole building loads - sized huge - so I don't need the another transfer switch.

        I'm still kinda chomping at the bit about 700 though. If I had unit lighting equipment, it would only come on for the short interval while the generator transferred. Because there is no normal panelboard. All panelboards are emergency. That just seems wrong. I know I've done it that way before - because where I've had to use a whole facility generator they didn't want the ten second outage. But something just doesn't seem right.

        Thanks for answering what I need to know. I appreciate it.

        Comment


          #5
          Originally posted by dema View Post
          You have totally answered what I NEED to know - I was looking in 700 instead of 702 and 702 applies. And 702 does not discuss the lighting in the same way. The generator is big enough for the whole building loads - sized huge - so I don't need the another transfer switch.
          You are not yet understanding.

          You cannot use one transfer switch, you will need one transfer switch for the loads that are optional 702 type loads you will need a second transfer switch for the required emergency type 700 lighting.

          OR

          Stick with one transfer switch and provide the required emergency lighting with battery units throughout the building.

          Comment


            #6
            702

            That is not what I read. I read either or. Please send chapter and verse of what you are reading. If the generator is large enough to handle all loads - the same size as the utility service - then I do not need a separate transfer switch. If you still believe I am wrong, please send the reference. Thank you.

            Comment


              #7
              700.2 Definitions
              Emergency Systems. Those systems legally required and
              classed as emergency by municipal, state, federal, or other codes,
              or by any governmental agency having jurisdiction. These systems
              are intended to automatically supply illumination, power,
              or both, to designated areas and equipment in the event of failure
              of the normal supply or in the event of accident to elements of
              a system intended to supply, distribute, and control power and
              illumination essential for safety to human life.

              700.5 (D) Use. Transfer equipment shall supply only emergency loads.

              Comment


                #8
                Originally posted by dema View Post
                T If the generator is large enough to handle all loads - the same size as the utility service - then I do not need a separate transfer switch. If you still believe I am wrong, please send the reference. Thank you.
                I do not believe you are mistaken I know you are mistaken.

                That generator that was selected to be large enough for all the loads can be connected in a way to do that but it will take a minimum of two transfer switches.

                Pharon has posted some of the code sections.

                You cannot supply optional loads and emergency loads through the same transfer switch, panels, conduits, junction boxes etc. The emergency systems have to be separate from from the other power wiring.

                Here is a graphic from Mike Holt and an article in EC&M about it. http://ecmweb.com/code-basics/emergency-systems-and-nec





                One last thing is that the customer does not get to decide what an emergency load is, that is up to the AHJ. The customer may well believe that their data center power is critical and an 'emergency' to them but it is only an optional load to the NEC.

                In a situation like you are describing often there will be a small transfer switch and panel to supply the small amount of true emergency loads and another full size transfer switch and panel to supply the optional loads.

                Comment


                  #9
                  Also consider this, the lighting fixtures that are specified to provide the legally required egress lighting must come on during any power failure regardless of any wall switches, time clocks, etc.

                  For instance, if you have ten fixtures in a hallway and two of them are needed for egress lighting those two fixtures have to be illuminated when the utility is off.

                  In the past those emergency fixtures where typically left on 24/7 as night lights, now with energy conservation they are often switched but if you do switch them you need to provide a way they will override the switch during a power failure.

                  As was mentioned, often people just install a large optional generator for the building and provide the egress lighting with individual battery units. Doing so eliminates a lot of cost and complication.

                  Comment


                    #10
                    Originally posted by iwire View Post
                    For instance, if you have ten fixtures in a hallway and two of them are needed for egress lighting those two fixtures have to be illuminated when the utility is off.
                    When the building is occupied.

                    Using GTD devices is an option if you have a large area.
                    The more they overthink the plumbing, the easier it is to stop up the drain

                    Comment


                      #11
                      Originally posted by dkidd View Post
                      When the building is occupied.
                      True, now how this will change the design I am not sure. It does alow for some more complicated control schemes to save a few pennies of fuel oil as these fixtures would only be running when the building is unoccupied and out of utility power.


                      Using GTD devices is an option if you have a large area.
                      I do not know what that is.

                      Comment


                        #12
                        Originally posted by dema View Post
                        I am struggling with the statement in 700.17 "Unless both ....are kept lighted."

                        The entire building is being put onto generator and night lights are not requested.
                        Will the generator be the main permanent supply and not just for emergency lighting?
                        Si hoc legere scis nimium eruditionis habes.

                        Comment


                          #13
                          Originally posted by iwire View Post
                          True, now how this will change the design I am not sure. It does alow for some more complicated control schemes to save a few pennies of fuel oil as these fixtures would only be running when the building is unoccupied and out of utility power.



                          I do not know what that is.
                          GTD= Generator Transfer Device.

                          JAP>

                          Comment


                            #14
                            Originally posted by jap View Post
                            GTD= Generator Transfer Device.

                            JAP>
                            Thanks, I have installed them I just never called it a GTD we call them emergency relays.

                            Comment


                              #15
                              Thank you

                              As I mentioned, my previous installations haven't hit this - generally I've done what you suggested. This time I'm using a GTD device because the facility is large, damp and not airconditioned and the lighting is LED.

                              Comment

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