30mA protection question?

[Foxmeister]

Have a board change to do in a property with all cavity/gyproc walls. Was considering the 50mm depth rule for the ring circuit and wondered if the 30mA protection would be required here.

After looking in the BRB and double checking reg 522.6.6 & 522.6.7, i noticed 522.6.8 which more or less states that unless the installation is in a location supervised by skilled persons, you must always protect the circuit with 30mA RCD irregardless of the cable mounting depth, kinda contradicting.

Ive always been taught that if you cant prove the cable is mechanically protected or the depth of cables is more than 50mm, you should always install the RCD/RCBO to protect which i normally did, but thought that this occasion would be ok for standard RCD.

As most jobs dont warrant checking walls and cable depths etc does everybody just automatically use RCBO's or 30mA RCD's when connecting rings etc?

 

[Andy™]

not much difference between an MCB & RCD and an RCBO...., only that you shouldnt have everything on one RCD

 

[a1spark]

I think you read that regulation wrongly.......If the cable is more than 50mm buried, then RCD is not required for this Reg [additional protection}....1st line tells you that .

If your working on the ring circuit you will need 30mA protection for the socket outlets though wont you OP ?

 

[Andy™]

but be careful since if its more than 50mm one side, it may not be on the other side

 

[Foxmeister]

I think you read that regulation wrongly.......If the cable is more than 50mm buried, then RCD is not required for this Reg [additional protection}....1st line tells you that .

Which regulation are you referring to here???

If your working on the ring circuit you will need 30mA protection for the socket outlets though wont you OP ?

Im not altering anything, would be changing the cu and obviously terminating circuit again. As stated would normally connect to 30mA for ring but thought that wouldnt be required if cables were outwith the depth zones?

 

[Andy™]

30mA required for all sockets... so unless you plan on changing every socket to an RCD socket, then it needs an RCD at the board

 

[a1spark]

Which regulation are you referring to here???Same one as you quoted 522.6.6

522.6.8 refers to walls containing, or constructed of metal parts...different reg.

Im not altering anything, would be changing the cu and obviously terminating circuit again. As stated would normally connect to 30mA for ring but thought that wouldnt be required if cables were outwith the depth zones?

AS I said all sockets less than 20A need RCD protection 411.3.3

 

[kme]

+1

 

[sparkytim]

As said there is more then one reason for installing 30 m A RCD protection.

Even sockets wired in surface trunking require RCD protetion UNLESS under control of skilled or instructed person, or designated for specific appliance.

 

[ianmacd]

As said there is more then one reason for installing 30 m A RCD protection.Even sockets wired in surface trunking require RCD protetion UNLESS under control of skilled or instructed person, of designated for specific appliance.

And thats not the case with a Domestic Dwelling anyway so all sockets require RCD's there.

 

[Andy™]

i could argue that my house is under control of skilled or instructed persons, and not fit an RCD

 

[professional]

And thats not the case with a Domestic Dwelling anyway so all sockets require RCD's there.

You are at liberty to use designated socket outlets WITHOUT the use of rcd protection in a domestic premises. It is up to the DESIGNER to assess the risk involved with such a course of action.

If you DO NOT possess DESIGN KNOWLEDGE AND EXPERIENCE as required by BS7671 to be deemed competent (i.e. the included definition of a competent person), then your sensible course of action is to follow guidelines provided for use in conjunction with BS7671.

 

[ianmacd]

[quote name='Andy

 

[ianmacd]

You are at liberty to use designated socket outlets WITHOUT the use of rcd protection in a domestic premises. It is up to the DESIGNER to assess the risk involved with such a course of action. If you DO NOT possess DESIGN KNOWLEDGE AND EXPERIENCE as required by BS7671 to be deemed competent (i.e. the included definition of a competent person), then your sensible course of action is to follow guidelines provided for use in conjunction with BS7671.

Not for general use.