Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 8 replies
  • Subscribers 32 subscribers
  • Views 3588 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

IP2X inside enclosures

wallywombat
Generally these days everything live(*) inside an enclosure like a CU (accessible only with a tool yada yada) seems to be IP2X - e.g. recessed terminal screws on MCBs, busbar covers, etc.


Is there anything in BS 7671 which enforces this? Or product standards like BS EN 61439? Or is it just down to good practice by the manufacturers?


(*), well, line anyway.
  • 0
    Interesting question!


    BS EN 61439-1:2011 8.4.2.3 gives conditions which must be satisfied when enclosures are opened. One of the choices is: "Where an intermediate barrier providing a degree of protection of at least IP XXB prevents contact with live parts, such a barrier being removable only by the use of a key or tool." Those busbar covers in consumer units seem to be able to fall off without a tool.


    BS EN 61008 and BS EN 60898 devices are to be marked with their IP rating if better than IP20. That implies that they should have IP2X protection, but I cannot find any clause which says so directly.
  • 0
    I think you are heading in a direction that will lead to madness here. If you need a tool to open something, surely there is actually no need to insulate anything? Take a typical busbar chamber. Are you trying to say that the busbars must be insulated (particularly where cables attach with bolts and nuts)? I think that this regulation applies to fuseboxes where there is an external door, and inside the breakers, mounted through a metal panel which is fixed with screws (say a Wylex 3 ph board). The idea that the inside should all be IP2X or whatever is daft, there are always slightly exposed bare wires and clamp terminal ends, whatever the screws are doing, and what about the neutral bar? Consumer units do have clip-on covers over the phase busbar, but they are pretty ineffective against a determined finger. Once you need a tool you bypass all IP ratings anyway, following this OP idea, nothing is safe at all! Trying to protect idiots from themselves (a common modern idea, perhaps "woke" for "accidents") is always impossible, someone will find a way someday. A long time ago many fuseboxes were interlocked with the switch lever and cover, and even some CUs. This idea has faded out, I have no idea whether it made a proper difference to accidents, probably not.
  • 0
    davezawadi (David Stone):

    Are you trying to say that the busbars must be insulated


    I'm not saying anything, or expressing any opinion. I merely observed that some forms of enclosure (such as CUs) often seem to have IP2X-ish protection, and was wondering aloud whether this is due to any regulations, or whether it's at the whim of the manufacturer.


  • 0
    So a consumer unit with a bus bar cover removed is still compliant as acess is needed with uses of a tool and the CU is labelled stating to turn off main switch before removing cover?
  • 0
    MrJack96:

    So a consumer unit with a bus bar cover removed is still compliant as acess is needed with uses of a tool and the CU is labelled stating to turn off main switch before removing cover? 


    Ah well now. Will you pass your C&G assessment, or even CPS annual assessment if you forget to put it back?


    I suppose that you must if there wasn't one there in the first place.


    I must say that some of these busbar and neutral bar covers would look more in place in a stationer's than a DB.


  • 0
    One day you will find an installation with reversed polarity or a neutral conductor will have a fault on it and the neutral bar which is exposed will be live.


    Not all the live parts in a consumer unit are insulated.


    Andy B.
  • 0
    Three examples of when I have found a live neutral bar in a consumer unit.
    • The neutral conductor failed on the DNO overhead cables supplying two houses, the one I was in was TT earthed so the earthing bar stayed at zero volts.

    • The guy who installed the consumer unit reversed the tails.

    • The PV installer fitted a four pole switch to isolate both the mains a PV and mis-wired it.


    There have been others, as said in the original post the line parts are shielded, not the live parts as the neutral carries current so are live conductors.
  • 0
     A long time ago many fuseboxes were interlocked with the switch lever and cover, and even some CUs. This idea has faded out, I have no idea whether it made a proper difference to accidents, probably not.


    The old grey coloured M.E.M. switch fuses/isolators had the need to turn off the main switch to enable the cover to be removed otherwise the cover was locked in place. 


    Many control panels in industry had a main switch that had to be turned off before a door could be opened to gain access to live parts. Unfortunately this was a pain to maintenance electricians when fault finding. So the main switch was cunningly turned on with the panel door open, and the safety design was defeated.  


    I once showed some students a bus bar chamber. We carefully removed the steel cover to see inside. It was interesting. The system was live. The act was foolish. I would not do it now. P.S. We all survived.


    Z.


Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines