tt system with rcbo's

[beaver74]

in a t.t system i have all way thought you need a 100mA s type dp rcd covering the whole installation
been to a job today and it is a standard board dp isolator and filled with rcbo's which yes they will protect as for high earth loop but they are only single pole am i right in my thought's

 

[KFORDHUNTER]

My thoughts are that if every circuit is protected by a 30ma rcbo what is the need for a 100ma main rcd. I thought the 100mA rcd was to protect all "other" circuits when you could still have circuits on mcb only.

 

[beaver74]

My thoughts are that if every circuit is protected by a 30ma rcbo what is the need for a 100ma main rcd. I thought the 100mA rcd was to protect all "other" circuits when you could still have circuits on mcb only.

yes but i am thinking that rcbos in general are single pole as apossed to double pole main rcd

 

[professional]

in a t.t system i have all way thought you need a 100mA s type dp rcd covering the whole installation
been to a job today and it is a standard board dp isolator and filled with rcbo's which yes they will protect as for high earth loop but they are only single pole am i right in my thought's

This configuration of board is probably what the IET intended to be the norm with regard to 17th Ed compliance. Can`t see a problem with it myself.

 

[YTSOxford]

Its a very expensive way of doing it tho! U can get DP RCBOs but they take up 2 modules; I used a 30ma to protect swa running a supply out to a garage.

 

[professional]

I agree that a board full of rcbo`s is way too expensive for many jobs in the domestic sector - the dual rcd boards are far more viable. Cost aside, rcbo`s just take up too much room in the currently produced boards!

 

[BillR3]

Most manufacturers now make single module RCBO's, Merlin Gerin and Wylex being the ones that I use on a regular basis.

 

[mrloy99]

I was under the impression that rcbo's were all double pole.That is why you have to connect the neutral into them and why there is a curly blue
lead hanging out of them-all I have seen and used have also been one
module type.Incidently they can be bought for around 15 quid a pop.

 

[professional]

The neutral on most rcbo`s is for functional purposes but is NOT usually switched, hence the single pole designation.