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testing safe of a 16 Amp commando socket/plug

Former Community Member
Former Community Member
Hello,i am an RF engineer and we have equipment that is fed by rack mounted AC/DC converters which charge batteries. these converters are wired into fused spurs using 2.5mm arctic blue cable routed into cable trunking. the 2.5mm cable is fixed in the rack before entering the trunking.

At the moment we are all trained in testing the circuit is switched off using a martindale VIPD138 voltage indicator and proving unit and then we lock off the circuit.

Everyone's training is due to expire and our company health and safety department want to change the installation from the fused spur to 16 Amp commando sockets/plugs rather than retrain everyone in proving the circuit has been switched off.


I have no issues with using commando sockets instead of the fused spurs but my concern is that if the nearest location the commando socket can be mounted is the other end of the room and there are numerous commando sockets supplying different racks how do you prove you have pulled the correct plug? surely you have to still be able to test the circuit has been switched off using the tester and training required.


I am having a discussion with the Health and safety department next week so any advice would be gratefully received.

Thanks
  • 0
    Your power supply currently goes into the rack - however it does that - add a commando socket on the power supply lead. 


    Preferably overhead or below the rack


    this would be the simplest solution but there are many others including removing the switch fuses and running in new supplies.
  • 0
    Why are these converters being isolated?
  • 0
    In a workplace, I do not think that you can do away with safe isolation so easily. It goes without saying that if I unplug, say a vacuum cleaner, I can be certain that it has been removed from all sources of electrical energy, so I do not need to prove dead.


    However, if there may be confusion as to whether a particular piece of equipment has been made dead, I agree that you still have to prove it dead.


    Either you roll up the supply cable and keep it in sight, or you have to lock off somehow.


    R13 of EAWR 1989 applies.
  • 0
    I’m pleased to see you said roll the flex up, I considered saying it, which comes under the heading of stating the obvious.
  • 0
    One factor as you raise is how well the risk of mistaken isolation is managed

    You replace training with accurate labelling of the plugs and sockets, and an assumption that everyone is awake and well lit.

    Occasionally folk will get it wrong  - so the next step in the process.

    also plugs are more likely to be damaged and need more frequent inspections than fixed switches. Especially if they drop down and may get trodden on.



    Now what is the penalty for getting it wrong ?

    If it is just that someone's lights go out and they cant read their notes, or a battery goes flat that is very embarrassing but no danger. However if the risk is that someone then touches a transmitter antenna and gets a burn off it, because it is still very much energised, that is a rather more serious matter, and if the penalty was they get  a shock off something that causes them to fall from height, then the risk is higher still.


    If it is anything more than mild nuisance, then in your shoes I'd be happier if some one fitted pilot lights to the gear being isolated - if the light is on, it's alive.

    Mike

  • 0
    If multiple devices are unplugged at the same time for electrical maintenance, I'd be very concerned about someone plugging the wrong one back in and killing someone. If someone is messing with the innards of isolated equipment in a crowded environment, I'd much prefer a regime of physical locking off and dead testing.
  • 0
    Liam T,


    Maybe Im looking at things from the wrong direction so forgive me!


    You mention in your post that "Everyone's training is due to expire" and your H&S team are wanting to change the physical set up as they perhaps feel that one day your are trained and competant to carry out that isolation task you have all been doing for x number of years. The very next day when your training cert has now went beyond its expiry date? you are suddenly not competant? I think this is a situation of tick box excersises, does your existing training cert actually have a expiry date on it? or has somebody just decided after three or so years that retraining is required or a simple update and refresh course.


    The cost to change the set up you described to a  plug and socket arrangement may be more than the training costs?


    I can only think of the hundreds of thousands of electricians, maintenance engineers etc out working today and when were they last assessed on safe isolation?


    If people require an refresher, can an authorised electrical person not just have yourself and colleagues run through the safe isolation and proving for dead scenarios with a few simple questions and a actual isolation carried out and that event then recorded.


    GTB
  • 0
    I believe in simplicity, so long as safety is not thereby compromised.

    The best approach in my view is to supply each equipment rack via an IMMEDIATLY ADJACENT plug and socket outlet. Not a distant outlet which calls for relatively elaborate testing and locking off procedures.

    If space is tight, consider socket outlets suspended from above or perhaps mounted on overhead tray.


    Consider also any risks from the internal batteries.
  • 0
    Sparkingchip:

    Why are these converters being isolated?


    To use a Martindale VIPD138 voltage indicator and proving unit to carry out safe isolation you have to open the terminal enclosure and test at the live terminals, which unless the equipment is being repaired and the enclosure needs to be opened for work to be carried out is not appropriate, is it?


  • 0
    We need the OP to come back and clarify - I had read it that there were exposed parts, as part of whatever the process is, and the question is more is unplugging and visual verification better than a switch.

    If not a pilot light would be a better design

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