Guys - Emergency Light Isolation Question

Discussion in 'Electricians' Talk' started by JP., May 7, 2014.

  1. JP.

    JP. Screwfix Select

    Afternoon lads and sorry for the stupid question.

    Ok emergency light all systems go no probs. However I was thinking that say if the light which the EM is on fails (lamp/Led unit failure) then someone might think that the Live to the faulty unit is switched off because they have negated power at the Mcb. However there will be juice from the EM pack as obviously it senses no power with the Mcb turned off and is doing its job. But the problem is that the L is energised and will give a belt ..I don't know what to think (obviously I won't get a belt because I fitted it - but someone else might work on it, and more then likely would get a belt) what to do? maybe it is ok as it is, or maybe a remote isolation switch has to be fitted in that particular light feed line? or maybe that test point on the inverter negates the power output and a switch will have to be fitted on that? Stupid I know, but there you go. Thanks lads for any inputs on this matter - all very important to me tbqh.
     
  2. BLUEJACKET

    BLUEJACKET Active Member

    Isn't the idea to test with a meter before carrying out any work that the unit is safe to work on? Are you saying that if the LED is off, someone might think the power to the unit has been isolated and start working on it...

    B J
     
  3. JP.

    JP. Screwfix Select

    That's what I am saying B J. Even though the Led light will be shining say red with the Mcb turned off - they might think - ''that's ok Mcb off, live negated, system dead, light live negated -however the EM unit has kicked in and hey presto 230v on the L. The chap grabs it, and the neutral and a belt will occur.
    Not everyone (maybe its a Diye'r like myself) follows juice tests before plunging in.. I do, but you know the crack tbqh.
     
    Last edited: May 7, 2014
  4. JP.

    JP. Screwfix Select

    10 minutes to wire and then you have to think about all this stuff - flipping heck its a joke.
     
  5. PJ Wales

    PJ Wales Member

    Well my emergency lighting does this with the LED, power on = green LED shows, power off = light is on LED is off, power off emergency light off = red LED.

    So if there was NO power at all from MCB then none of the above should be happening barring the emergency light being on.
     
  6. JP.

    JP. Screwfix Select

    Ok so right - the EM light lamp blows and this entails changing the whole unit. So the person doing it thinks ''I will turn off the Mcb'' which means that the EML Live is Live. Even though there is a Led showing that the power is negated (Red Led) the EM Live is energised - so the person grabs the L and gets a belt..I cant see this being in line with isolation regs tbqh. I think I will put a SP defeat switch in, and put the switch inside my soil stack - there will be a door for rodding access so I will put the switch behind the door..and label it up. When this switch is operated no live can show on the light L despite the EM throwing out 230v. That's all I can think of PJ - maybe ott I don't know tbqh.
     
  7. PJ Wales

    PJ Wales Member

    The EML should be throwing out the battery voltage not the main voltage, cos there is no live coming into the EML hence battery takes over and power up the lights.

    That the purpose of the EML, if the power goes the light comes on and remains on for as long the battery last which varies from 30 mins to 2hrs so from what I knows the live voltage when the light is on is the battery voltage.

    My EML is (believe it or not) an industrial lighting systems, don't ask why I have those??? It was here when I moved in and I rent not own my place. Yes it even got it's own break here fire alarm button BUT not linked to 3 other property which totally defeat the purpose of having 1 lol.
     
  8. JP.

    JP. Screwfix Select

    HI PJ - the PD on mine is 230v. Under power negate mode the battery voltage is fed into an invertor, which chucks out the 230v. If it was just battery voltage I wouldn't give a hoot, but my EM pack feeds a JCC 6 230v down-lighter.
     
  9. PJ Wales

    PJ Wales Member

    I might be wrong but someone who knows can correct me. If you tell someone the said light is an EML, I think they would know what is what and just isolate the unit by means of disconnecting the unit from the battery within as well as isolating the live feed from MCB.
     
  10. JP.

    JP. Screwfix Select

    It would be a right job pulling that lot through the down light hole, and sliding it out of the fire bag to disconnect the battery PJ.

    I've decided to put a SP defeat switch in - this will be lined on the invertor output and obviously the SWL - depending on what mode it is in. At least when the switch is opened the light live is totally isolated. What a performance - but I can see no other way of making it totally safe. Probably another own regulation but what the heck - not happy though doing it but even if the regs say it is not needed, my own self says it is needed..flipping heck I will be glad when I have finished the electrics tbqh.
     
    Last edited: May 7, 2014
  11. Rulland

    Rulland Screwfix Select

    That's what I do, if working on a fitting that needs checking/remedials, confirm 230v and also disconnect battery pack if required, anyone who gets a belt from an emergency fitting should know what they're doing tbh.
     
  12. Bazza-spark

    Bazza-spark Screwfix Select


    Hi JP

    The light should be installed following the manufacturers instructions. It will be CE marked showing that it complies with the relevant product standards. As long as it is installed to the recommendations it will be fine. If you modify the light you invalidate the CE mark as it no longer complies with its product standard.

    Having the LED visible will let anyone working on the light in the future see that is is an emergency light so they can take the appropriate actions to ensure safe working.

    Kind regards

    BS
     
    FatHands likes this.
  13. Lectrician

    Lectrician Screwfix Select

    The EM version surely only supplies SELV to the LED can? Not seen a JCC one, so could be wrong, but I would not think the EM module you have outputs mains voltage to sustain the fitting. In any case, it operates a greatly reduced output.
     
  14. JP.

    JP. Screwfix Select

    Hi Baz and many thanks for your reply. Ok will do as you say - the Led indicator will be in the ceiling, and as you say anybody working on it should know what they are doing. So I will fit it as per manufacturer method. Thanks once again Baz, appreciated.
     
  15. JP.

    JP. Screwfix Select

    Hi Lec. The EM version supplies a standard JCC 6 downlighter with 230v (from the invertor - the 230v is I admit a presumption, it might be less, maybe I will measure the voltage) I am testing it at the moment with an 11watt CFL (haven't got the ceiling up yet) and it fires that up ok when supply is turned off. The Led is green for normal and red when the supply is turned off. How far can I go really? I will just do it as Baz said - the Led indicator will be in the ceiling - it is up to the person working on it to check for PD etc as it is an EM unit. Its all wired to the manufacturers stipulations. I haven't cabled the test point but simply flipping the Mcb will check it is working ok.

    Cant do anymore, and will not fit iso switch etc now. Just leave it as it is ''out of the box'' as I tend to complicate matters tbqh- thanks Lec.
     
    Last edited: May 7, 2014
  16. Lectrician

    Lectrician Screwfix Select

    Would be interesting to see the voltage. If you're messing with it, you may as well meter it!

    I suspect its 230v switched, but lower voltage on battery. Perhaps 24v. It is only 10% brightness on battery.

    A CFL will fire up at very low voltages. Often used in 110v strings. They also carry on working when the DNO loose an HV phase, causing low volts on the LV output of a TX.
     
  17. BLUEJACKET

    BLUEJACKET Active Member

    Correct, so as suggested discon the battery pack

    B J
     

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