Type c RCBO

[mick21]

Hi all
I have recently obtained some type c RCBOs, can anyone tell me if these would be ok to use in a domestic consumer unit, they are wylex and MK. Not sure if they would fit.
Thanks in advance.

 

[ezzzekiel]

yes they will fit fine and operate the same way apart from the higher operation time for inrush current

 

[johnboy6083]

dont forget that to achieve correct disconnection times, the Zs value has to be less than a type B.

 

[IQ Electrical]

Interesting point here!

City & Guilds 2391-10 question:

List the possible methods of overcoming an exceeded maximum Zs on a circuit currently protected by a BS 60898 'B' 32 MCB

 

[mick21]

Thanks for the advice chaps

dont forget that to achieve correct disconnection times, the Zs value has to be less than a type B.

 

[malcolmsanford]

Interesting point here!

City & Guilds 2391-10 question:

List the possible methods of overcoming an exceeded maximum Zs on a circuit currently protected by a BS 60898 'B' 32 MCB

Increase the size of the CPC would be one and the other would be fit RCD/RCBO ......................so the zs if RCD/RCBO would be a 1667 as it would have to be a 30mA ......................correct sir?

 

[telectrix]

max. Zs for type C is half of a type B

 

[johnboy6083]

ive made a schoolboy error! max Zs for RCBO is 1667ohms!

 

[telectrix]

Increase the size of the CPC would be one and the other would be fit RCD/RCBO ......................so the zs if RCD/RCBO would be a 1667 as it would have to be a 30mA ......................correct sir?

or reduce the rating of the breaker ( if load will allow).

 

[malcolmsanford]

ive made a schoolboy error! max Zs for RCBO is 1667ohms!

Spot on johnboy the relationship with the B,C or D would be used for inrush currents on the RCBO and therefore the over current part.

As the RCD side of the RCBO is for fault protection then the Zs would be 1667.

 

[johnboy6083]

or, supplementary bonding?

 

[IQ Electrical]

Exactly Malcolm and johnboy6083 1667 Ohms !

 

[malcolmsanford]

or reduce the rating of the breaker ( if load will allow).

Not on the 2391-10 questionTtel your 3 marks would be

Increase CPC size
Supplementry bonding
RCD/RCBO

 

[IQ Electrical]

Yes, supplementary bonding, increased CSA of CPC, RCD protection incorporated, reduce In of the MCB or reduce the type eg. 'D' to 'B' if the load characteristics allow. (not applicable in this situation as the question relates to a 'B' type.)

 

[High Tower]

Interesting point here!

City & Guilds 2391-10 question:

List the possible methods of overcoming an exceeded maximum Zs on a circuit currently protected by a BS 60898 'B' 32 MCB

Increase the CSA of the CPC