Within BS7671 there is a lot of information in the use of RCBOs and was wondering if in certain applications like industrial sockets BS90437 and lighting Circuits whether these would pose a nuisance tripping action.Just wondering what the general consensus

BS60439-3

That's the old standard for DBs isn't it? (replaced by BS EN 61439-3 about 10 years ago?)

As for RCBOs BS 7671 has no blanket requirement - 30mA RCDs are only demanded for additional protection on lighting circuits in domestic/household situations. Normally no requirement for hard-wired equipment, just sockets (<=32A) used by ordinary persons and for portable equipment outdoors. Soft sheathed cables concealed in walls normally aren't a feature of industrial situations.

Most single appliances suitable for being powered by a plug have relatively low earth leakage (protective conductor) currents - otherwise you'd have other constraints, such as having to provide high integrity c.p.c.s. It can be an issue in some situations though - e.g. server racks containing dozens of mains powered items but the whole thing still on a plug & socket for maintenance purposes. In such cases there is an option to use a risk assessment to avoid the need for 30mA RCD additional protection.

Sometimes high starting currents have been know to false trip RCDs - usually the answer to that is to use an RCCB with a higher carrying current rating (e.g. a 40A/30mA RCCB plus say a 16A MCB, rather than a 16A/30mA RCBO).

   - Andy.

Hi Andy,

Yeah, I've got my standards wrong it should of been BS60947-3 its the Industrial standards and not 90437 which I gave first time round. 

Hi Andy,

Yeah, I've got my standards wrong it should of been BS60947-3 its the Industrial standards and not 90437 which I gave first time round.