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Topic Title: Plastic Consumer Units
Topic Summary: New Ring Main Installation
Created On: 08 November 2017 10:08 AM
Status: Read Only
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 08 November 2017 10:08 AM
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Just looking at installing 1 no new Ring Main Circuit for Computer Use Only Socket Outlets and the Consumer Unit is found to be Plastic - Hagar Vision 6ka MCB Type. Just wondered whether the recommendations would suggest replacing the Consumer Unit to metal or whether it is acceptable to connect the new 32A Ring circuit to the existing Consumer Unit using a 32A RCBO without the need to replace the Consumer Unit? The consumer unit is located in a Care Home located at h/level. Look forward to peoples thoughts on this....

Loose Wire
 08 November 2017 02:14 PM
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As it's a care home it's deemed not to be domestic (household) premises, so BS 7671's requirement for non-combustible CUs (reg 421.1.201) doesn't apply.

Even is it was domestic, I know of no regulation that requires the replacement of existing equipment provided it allows the new work to comply with the current regulations. You can recommend replacing anything with a later and supposedly better version if you wish, but that can't really be a pre-condition for doing new work.

- Andy.
 08 November 2017 03:05 PM
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Yes it does state that non-combustible switchgear enclosures to be used for domestic premises only.
Although if I was a designer of care homes I would certainly consider the domesticity of its application and query the day to day carers possible fire safety competence, ability to provide full evacuation,
I might take into the account the building classification BD2 and BD4 as further evidence.



 08 November 2017 03:54 PM
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How many computers? There might be high protective conductor currents, leading to nuisance tripping of the rcbo.
 08 November 2017 05:17 PM
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OK to add new ring to existing, even if domestic.
May be worth a mention as a note on the paperwork if it looks like there is potential for other problems, or if you were changing it any way, then new regs apply.

regards Mike
 08 November 2017 08:33 PM
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Thanks for the great feedback guys. Just to clarify that the care home has a fully addressable analogue fire alarm system in place designed to L2 with automatic detection within every room. The consumer unit in question is tested 5 yearly by a designated maintenance company, consumer unit Scored a 7 out of 10 upon a recent visual inspection, rcds are tested quarterly by the site supervisor and there is a maintained emergency lighting system in place, so pretty much everything is in place. Staff are trained for fire evacuation. The sockets are to be engraved computer use only, no more than 8 sockets per circuit so high protective conductor current shouldn't be an issue so hopefully limiting to a max no of 8 will prevent any nuisance tripping on a 32A rcbo. The consumer unit is fed by a 25mm 3 core SWA supplemented with a 25mm high integrity earth from the main panel board via a 63A MCCB to BS60947-2. Everything pretty much pucka!!!

Loose Wire

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