LED inrush currents

Discussion in 'Electricians' Talk' started by raster ozi, Mar 24, 2015.

  1. raster ozi

    raster ozi New Member

    Hi all.

    I installed 2x50w led floodlights and 8x30w floodlights on one 20a switch. Total load is 340w.

    The switch would not turn off (lights stay on and switch springs back to on position). I replaced the switch 3 times with the same result.

    I have never come across this situation and there is virtually no advice anywhere as to how many floodlights can be operated by one switch.

    I did some quick research and discovered that each led driver can take upto 40 amps of inrush current! Is this right?

    I think this inrush current is welding the switch closed. When I isolate the supply the switch will still not go off until it has cooled for a minute, then seems to function normally.

    I am returning to site tomorrow to split the floodlight load across two switches and will let you know if this cures the problem.

    Has anyone else had to deal with this scenario because I would like to hear your views on this...
     
  2. stateit

    stateit Screwfix Select

    Not installed any big LEDs like that.

    Sounds like you'll need a suitably rated contactor to switch it.
     
  3. raster ozi

    raster ozi New Member

    Yes, but you wouldn't think so looking at the rated load. Obviously this area has not been explored enough.

    Didn't have this problem with halogens, it was easy to work things out

    I have been using LAP and BG weatherproof switches but technical info is not readily available from either of them.

    The MK switches state a 3mm gap and max making and breaking capacity on their technical pages - why cant all manufacturers post the tech sheets on the net?

    I installed these floods for a market fish display but they are the same floodlights sold everywhere for domestic commercial and industrial applications but little is said regarding the drivers for these lights. There must be many places where several units are required to light up an area and switched from one source.
     
  4. KIAB

    KIAB Super Member

    Can't be right that figure,cannot see how a 50w led could pull such a high load, but then it would only be for milliseconds so maybe, contact led floodlight makers/suppliers should be able advise you, I'm interested to know more.

    But you can buy' led peak inrush current limiters', remember reading a article in PE magazine a while back.
     
    Last edited: Mar 24, 2015
  5. stateit

    stateit Screwfix Select

    A bit of data I've dug up:

    And an instance for a Philips Driver:

    So a huge inrush current. Not long enough to trip a breaker - but enough for a spot-weld on a low-rated switch.
     
  6. raster ozi

    raster ozi New Member

    Hi all,

    Been out to site again today. This is what I have done and it seems to have fixed the issue.

    1. Removed 20 amp splash-proof switch controlling the 10 LED floods
    2. Fitted MK splash-proof garage unit with two 6 amp MCB's and split the floodlights across the two breakers which now act as both overload protection and functional switches. These are backed up by a 16 amp MCB in the consumer unit

    Everything works ok now with MCB's switching load without any sticking or tripping.

    I dont know if fitting two ordinary switches would have done but didn't want to chance it so I went for the MCB's due to their 6000 amp breaking capacity!
     
  7. unphased

    unphased Screwfix Select

    Good post, raster. It is worth noting that LEDs pull large inrush currents. Glad you sorted it mate. :)
     
  8. raster ozi

    raster ozi New Member

    Thanks unphased. This episode tells me that no more than 3 or 4 LED floodlights should be controlled by one switch, and that switch preferably needs to be a good brand name if it is to last.

    Thanks to all contributors to this post...
     
  9. Lectrician

    Lectrician Screwfix Select

    Would be interesting to know the manufacturer or the driver (not so much the fitting)?

    Last year we fitted LED highbays throughout a warehouse, 138watt each. Each fitting had 10 chip sets, two chip sets in series from one driver, so each gear tray contained 5 drivers. Each circuit had 4 fittings, so 20 drivers. These are happily running on C10 MCBs with 20amp MK grid modules.

    Would be interesting to know.
     
    KIAB likes this.
  10. raster ozi

    raster ozi New Member

    TBH the floods I used were unbranded via Ebay cos the client wasn't prepared to pay any more. There are literally dozens of suppliers selling these cheap Chinese floods. Reliability-wise I have only had one or two failing prematurely, both times the chip went open circuit out of the 50 or so that I have fitted over the past year.

    BTW, the chips are two a penny and the drivers are cheap as well so it does not pay to get the lights from electrical wholesalers until the price comes down a bit or the client insists on them (and is prepared to pay for them).

    As far as the inrush currents go, it would be interesting if someone tested a sample of LED floods from both cheap Ebay ones to those supplied by electrical wholesalers to compare if the latter ones have their inrush currents limited through better design.

    I for one would steer clear of those units tested to have excessive inrush currents even if it cost more to get the better ones, I still feel the suppliers need to come clean about this as everything and anything is LED these days!
     
  11. KIAB

    KIAB Super Member

  12. unphased

    unphased Screwfix Select

    They are quite quirky these LED floods. Completely different to halogen versions. When I first started installing them I was caught out because I thought one had failed on first power up. It sort of quickly flashed then went off. This caused some embarrassment because I got the customer to change it. Halogen floods come on during warm up and then go off. Any way since then I've realised this is normal and most of them give a quick flash when powered up. I have used JCC and Lumineux floods and had one fail so far, the JCC.
     

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