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Plastic consumer units/enclosures etc

I have a job where a small former outside toilet is being converted into a hobby pottery complete with water supply and small kiln.

I propose to fit a small plastic consumer unit with the appropriate IP rating for protection against ingress of water.

This will be a home brew job with a generic enclosure and a RCD main switch and mcbs from my spares stock.

I have seen many metal enclosures rusting quietly away in detached garages/w/shops/outbuildings and thought they would be better served by using plastic.


I think there is still a case to be made for fitting plastic consumer unit enclosures in outbuildings in order to prevent deteriation caused by external influences. Moist atmosphere, unheated spaces and the like.


Any other like-minded souls out there?

Comments welcome.
  • I am a like minded soul. Whenever there is little/no risk of their spontaneous combustion causing a problem to the main residence or sleeping quarters then I install IP rated plastic CUs. 


    I too have seen rusty metal CUs and switch gear in outbuildings and even in houses where they are mounted somewhere a little damp or cold and even in the case of one TP board near the entrance to an open west facing barn.
  • There is no prohibition of plastic CUs.


    To comply, it should, strictly speaking, in domestic (household) premises, be non-combustible or be in a non-combustible enclosure.


    Unfortunately no definitions exist in BS7671.


  • Use a BG consumer unit with an IP rated aluminium enclosure. 


    Andy Betteridge
  • It's outside the dwelling, plastic no problem. In any event the 18th Ed guide book is not too good on advice for fuse boards, last year one of the guys on here ordered an IET publication on consumer units. I don't think he ever got it. 

    Regards, UKPN.

  • Sparkingchip:

    Use a BG consumer unit with an IP rated aluminium enclosure. 




    Agreed! I don't think that they have been around long enough to know how long they will last.

  • To be brutally frank, I truly believe that the IET has lost it's purpose as arbiter of best practice when it comes to electrical safety.

    It is turning itself into a farcical organisation which has become the crutch of ignorant lawyers and so-called 'professional witnesses' who should know better.
  • WHJ


    I think you being very unfair on the IET. The change in the 17TH Edition to non-combustible consumer units was made at the request of the London Fire Service who made their case to JPEL due to the number of fires they were attending involving consumer units. 


    My my personal view is if they are unsuitable for installation in domestic premises they are unsuitable for installation anywhere. I think you may have a job buying a new plastic consumer unit from a reputable wholesaler now. You have already been advised to use the cast BG garage unit which is also IP rated. When I get around to replacing my old metal MEM unit in my workshop I will use the BG unit. I have already replaced the consumer unit in the house with a Wylex metal unit.


    As an IET member I feel it is insulting and offensive to the IET, and to other contributors who offer free and expert advice here, to log on to this free forum and insult the provider. You may feel more at home on the Screwfix forum as you clearly have no confidence in the IET!
  • Lets hope the wholesalers keep a good stock of plastic RCDs with enclosures for up front protection on TT systems with steel fuseboards!

    Regards, UKPN.

  • UKPN:

    Lets hope the wholesalers keep a good stock of plastic RCDs with enclosures for up front protection on TT systems with steel fuseboards!

    Regards, UKPN.




    Well now, instead of your typical Wylex REC2 switch, you can have one with an RCD instead.

  • In perhaps 10 to 20 years time, when the mania for swapping CUs has died, and most houses  have a ten year old metal consumer unit, it will be interesting to look at the fire stats, and the electrocution stats, and see if the call on the metal CU  was in fact the right one.

    There will be plenty of comparison data from other countries as almost nowhere else on the planet considers a plastic enclosure for electricity to be a bad idea. Right now it is too soon to say.

    I am in agreement by the way that I think there are plenty of damp places, and even some dry situations where the Ze is high, where a metal box is not a sensible option.