17th edition Tt board

[lkayelectrical]

Ok first fuse board change to do with a Tt apply since 17th edition gas come out, (before any one comments have my 17th update in a few week)

What's the rules on it now? Can you just get away with a split load rcd boar with 2 x 30ma rcds in? Or do you still have to have a rcd main switch?

L

 

[Doc Hudson]

I thought the beginning section of the on site guide gave examples of typical fuse box layouts RCD arrangements for TT, TNS, TNCS? Don't have a copy at hand so cant remember sections or pages.

Doc H.

 

[SLIPSHOD & SLAPDASH]

Dont listen to Steptoe, fit 30ma Rcbo's on all your circuits in a insulated board (non metalic) and the jobs a good-on

 

[johninlondon1]

In the case of the CU being metal constructed, you will need a 100mA RCD to be installed between it and the origin of the supply. This will give discrimination between it and any 30mA rcd units downstream.

 

[NozSpark]

In the case of the CU being metal constructed, you will need a 100mA RCD to be installed between it and the origin of the supply. This will give discrimination between it and any 30mA rcd units downstream.

I'm afraid it won't,, it needs to be an 'S' type (time delayed) before you get proper discrimination

 

[steptoe]

Dont listen to Steptoe, fit 30ma Rcbo's on all your circuits in a insulated board (non metalic) and the jobs a good-on

it all depends on your interpetation of the regs,

personally I insist on DP disconnection of circuits in instances of fault,

hence the insistence on RCD or DP RCBOs, this also minimises the daisy chain effect, and could be arrived at by use of a 100mA front end before the RCBOs,

yes, on further investigating and looking into this,

I feel that the DP disconnection could be achieved via a front end RCD.

obviously not everyone is of the opinion that DP protection is required, so if you feel/read/interpet the regs that way then you may feel SP RCBOs are fine.