IET announces new amendment to BS 7671 (IET Wiring Regulations)

The first mention of Additional Protection [AP] in BS7671 is 410.1 [ scope of Chpt 41].....I think..

The first mention of AP with reference to RCD  is 411.1... I think...

415.1.1 is very specific of what is expected of an RCD for AP.

That is all straightforward.

Then 531.1.1 : Devices for protection against electric shock by ADS shall be suitable for isolation in accordance with chpt 46 and 537.

There is the table for 537 as a "guide" for suitability for switching/ isolating etc. In the RCD bit it lists BS60947-2/61008/61009 as okay for isolation. Ah you think! But a removable BS1361 fuse , a switched fused connection unit, a plug and socket are also all suitable for isolation as listed in same table.

Again you have to ask "when is an RCD not an RCD?"  Or even , "when is a plug and socket not a plug and socket?"

Perhaps they can be both RCD and plug and socket or RCD and fused connection unit.


Something is only isolated [properly] when there is some means to prevent it being energised again inadvertently, such as locking off , removing the fuse or unplugging [ though strictly the last two may need further steps if the mischievous are about ].

If it is not an RCD do not call it an RCD, as it is generally expected an RCD is a protective device and BS7671 says they are for additional protection, if the correct rating.




NB this was composed before the post by Mr Kenyon

The first mention of Additional Protection [AP] in BS7671 is 410.1 [ scope of Chpt 41].....I think..

The first mention of AP with reference to RCD  is 411.1... I think...

415.1.1 is very specific of what is expected of an RCD for AP.

That is all straightforward.

Then 531.1.1 : Devices for protection against electric shock by ADS shall be suitable for isolation in accordance with chpt 46 and 537.

There is the table for 537 as a "guide" for suitability for switching/ isolating etc. In the RCD bit it lists BS60947-2/61008/61009 as okay for isolation. Ah you think! But a removable BS1361 fuse , a switched fused connection unit, a plug and socket are also all suitable for isolation as listed in same table.

Again you have to ask "when is an RCD not an RCD?"  Or even , "when is a plug and socket not a plug and socket?"

Perhaps they can be both RCD and plug and socket or RCD and fused connection unit.


Something is only isolated [properly] when there is some means to prevent it being energised again inadvertently, such as locking off , removing the fuse or unplugging [ though strictly the last two may need further steps if the mischievous are about ].

If it is not an RCD do not call it an RCD, as it is generally expected an RCD is a protective device and BS7671 says they are for additional protection, if the correct rating.




NB this was composed before the post by Mr Kenyon