Old Distribution Board and Present Certification

There is nothing wrong with any of your list. MCBs may seem to be nice but in an industrial environment, BS88s are often better and just as convenient. The only snag with fuses is that they are not ganged, so the loss of a single fuse may damage certain loads (typically motors) due to phase loss. However, correctly set motor overloads should cope with this in most instances. Fuses are perfectly in line with BS7671, certificates should be no problem.

Thanks Dave, so I think you are saying that just because it is old does not mean it cant be certified to 18th Edition.

However other circuits are fed from here, in our case a local 3ph socket, for 18th I suppose this has to be RCD protected. My confusion is that if we do not change the board and only replace the cable to the motors then how can certification be achieved?

How old is the DB? Asbestos in the fuse carriers?

Who said a new DB is  required before it can be "certified".

What is your particular involvement, for example, are you an electrical contractor or, say advising one? 

We are designing a control panel that controls motors on this site, the control panel will be fed from this DB board.

The team responsible for installation of "fixed wiring" said the DB board would require replacement if they were to run a cable to our new panel in order to certify properly,


We only require a single 3ph cable to be fed from the DB board, seems to me the to change a DB board for a single cable is unrealistic, but if thats the rules.......

The basic rule of additions is that only the new work has to comply with the current regs, but that the new work mustn't be "lessened" by the old work. So for example adding a new socket to an existing non-RCD circuit wouldn't comply. Conversely, replacing a DB doesn't mean all the downstream circuits must suddenly comply with BS 7671:2018 (644.1.2)

Thanks.  So this is one new circuit . If ADS at the Origin and at this DB are adequate, the DB itself appears servicable , no damage, good IP rating and it will handle any new, additional demand of the new circuit, then no problem. If for any reason you were wanting an RCD on the new circuit, it can go in a separate outboard enclosure , for example.

Your Certificate will just be for the new cabling, new circuit, making it clear the DB and other final circuits are existing and nothing to do with you. Your Certificate will have just one circuit recorded in the schedules. You will make a comment on the existing Installation; has it been periodically inspected? Does it look a bit unloved ? Generally making it clear that your Certificate is not absolving the existing installation of all its sins. Limiting your liability is the name of the game. The last one in will always get the initial blame for  stuff time expiring if you have not been tight with your detailing on the Certificate .

I think what you need from the Installer is simply  the reason why they  think the DB is not suitable for an  addition.

I think it simply a matter of having no RCD on the socket, but as you all suggest here that does NOT mean you cant certify your own cabling works.


I suppose as you suggest we could also use a separate enclosure for RCD to tidy it up.

If it's only one socket-outlet supplied by the circuit, and RCD is not required for other purposes to protect the cable itself, then surely one of those EN 60309 socket outlet assemblies with built-in RCD enclosure would do the trick? They also come in the EN 60309-4 (with isolator) variety.