recently carried out fixed wire testing in comms data rooms remove cover off boards and find the following 16mm tails suppling db which was 125amp dorman smith disconecter switch pigy backed off the same tails 16mm then supplied another db with exactly the same 125a switch in then would you believe coming off a 32a breaker it supplys another db 125a switch standing there bewildered i tell the in house sparks you cANT DO THAT THEY SAY WHY BECAUSE the 3 boards are only pulling 11amps between them and they are in control of the data rooms so no one else can plug in any extra kit hit me with it lol
being very kind to them i carry out individual testing which is all ok but i give it a code 3 to which there not happy
M
malcolmsanford
To be honest I can't see what really is the problem either.
The switch disconnect is exactly that, regardless of it being 125amps or not it is just a switch not a protection device.
What is the protection device that is covering the 16mm tails to the first board?
There is also nothing stopping you piggy backing a switch like this, IMO it is bad practice but 2 X 16mm cables is 32mm as close as, and a 125amp switch I would imagine can take both cable comfortably.
Though not exactly a great design, as long as the original protection device In is suitable for the 1st set of 16mm tails there would seem to be nothing unsafe about it
The switch disconnect is exactly that, regardless of it being 125amps or not it is just a switch not a protection device.
What is the protection device that is covering the 16mm tails to the first board?
There is also nothing stopping you piggy backing a switch like this, IMO it is bad practice but 2 X 16mm cables is 32mm as close as, and a 125amp switch I would imagine can take both cable comfortably.
Though not exactly a great design, as long as the original protection device In is suitable for the 1st set of 16mm tails there would seem to be nothing unsafe about it
i agree malcom it posses no immediate danger but just dosnt look or sound right would you of not coded it at all when asked my explanation was it dosent conform to bs 7671 would you agree with me or not
M
malcolmsanford
Well OK FE, what part of the regs does in not conform to in your opinion?
Unless I found
a) that the Protection at the origin was undersized for the 16mm tails, for example you had a 160amp MCCB protecting the installation then yes I woulds have coded it.
b) If there were visible signs at the switch disconneter that the cables were under strain, that there were signs of heat damage, that you could easily pull the conductors out, in this case I would have coded it.
The bottom line is if the original tails are protected by a suitable size PD, it is irrelevant how many DB boards that are piggy backed off of it.
As said it's not the greatest design, I personally would have use a bus chamber for something like this, but everything costs money and I guess that may have been a factor.
Unless I found
a) that the Protection at the origin was undersized for the 16mm tails, for example you had a 160amp MCCB protecting the installation then yes I woulds have coded it.
b) If there were visible signs at the switch disconneter that the cables were under strain, that there were signs of heat damage, that you could easily pull the conductors out, in this case I would have coded it.
The bottom line is if the original tails are protected by a suitable size PD, it is irrelevant how many DB boards that are piggy backed off of it.
As said it's not the greatest design, I personally would have use a bus chamber for something like this, but everything costs money and I guess that may have been a factor.
ok lads thanks for your advice will take it on board tel not been on too much recently are you back on you feet now
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