RCD protection on 3 phase sockets/18th edition

[leep82]

Ive recently watched some short online videos from the NICEIC which talks about some of the changes that will be incorporated in the 18th edition. One of these changes i think says that all socket outlets upto 32a will require RCD protection.

I have recently been to look at a job where the customer requires 2 x 3 phase supplies ( 1 x 16a and 1 x 32a ). Both supplies will be via commando socket outlets for a dedicated piece of equipment. I seem to remember that when the latest ammendment was introduced there were certain dates that you could install upto, ( e.g insulated consumer units in domestic premises were ok upto said date or ongoing jobs started prior to the date could continue to be installed to the pre ammendment standard, hopefully ive understood that correctly).

My question now is regarding the job i will hopefully be undertaking and whether to provide RCD protection or not. Obviously we are still working to the 17th edition but is it worth thinking ahead and ensuring that my install is still compliant in the months to come?

 

[Lucien Nunes]

Situations where I would exempt a socket outlet from RCD protection are those where the disadvantages of fitting it overshadow the advantages. For example, in my own workshop I have sockets into which strange pieces of equipment, possibly faulty or experimental, are connected for test and evaluation. In this situation unexpected nuisance tripping is likely and might cause undesirable results or prevent the work being completed successfully. A qualified electrical engineer would be supervising, would use appropriate SSoWs, and the sockets are isolated when not in use.

Another situation is where sockets are part of installed systems, e.g. the large ELV DC supplies we install in pipe organs, that use a 13A socket for ease of replacement instead of being hardwired in. They are only accessible to technical maintenance crews often in a permit-to-work areas and will only ever be used for that installed PSU because there's nothing else going on up there. In this application, although the RCD offers little additional safety, a nuisance trip could result in an entire evening's programme being cancelled, as there might be no-one in attendance able to access and reset it in a reasonable time.

Without background knowledge of your site I would say there is merit in RCD protection and no extenuating circumstances that would exempt it. However, there might be specific reasons why the equipment is not compatible, e.g. if the welder is of a type that might generate enough leakage to cause nuisance trips, or if the saw has injection braking where loss of supply could create a greater hazard than RCD protection removes. Those are aspects that needed consideration before installation.

 

[Ian1981]

One of the exceptions of omitting rcd protection for sockets upto 20 amps is a suitably labelled socket for an item of equipment no risk assessment mentioned if choosing this method in bs7671.
One other omission is a documented risk assessment.

If opting for the labelled item of equipment option, why do a risk assessment for it?otherwise you would only have the one option open to you in the first place and not 2 options given in bs7671.