Best Options for old 3ph instalation?

[Lectrician]

It makes no difference being three phase or single phase or split phase with a shock line to earth. In all cases it's 230 volt.

Are you sure about that? Isn't the RCD's CB transformer/sensor measuring the imbalance between phase and neutral currents? In which case would it not trip on a phase-phase shock as well as phase to earth, as the phase current would not be returning via the neutral in either case?

All phases and neutral all go through the same current transformer so as long as that is the case the shock phase to phase or phase to neutral will not trip a RCD. Where the neutrals or phases are split as with a RCBO then any connection between either phase or neutral be it the same or different phase with either phase or neutral which is not going through the same RCBO will trip it. So yes if you fit three RCD's one for each phase then phase to phase connection would trip the RCD device, but then no point having a three phase supply as one could not use it as a three phase supply.

I think he meant single pole RCBOs on different circuits. Or RCDs on different phases. A P to P fault would then trip the RCD.

 

[ericmark]

It does seem I am outdated BS EN 60439-3 has been replaced by BS EN 61439-3:2012. I will guess this covers the new fire resistance requirements.

I found this:-

BS EN 60439-3
Low-voltage switchgear and controlgear assemblies. Particular requirements for low-voltage switchgear and controlgear assemblies intended to be installed in places where unskilled persons have access to their use. Distribution boards

Publication Date: 28 June 1991
Amendment Date: A2 2001
Replaces: BS 5486-12:1989, BS 5486-13:1989

BS EN 60439-3 gives supplementary requirements for enclosed distribution boards (DBU) which are stationary, type tested assemblies (TTA) for indoor use, containing protective devices and intended for use either in domestic (household) applications or in other places where unskilled persons have access for their use.

Control and/or signalling devices may also be included. They are for use on a.c., with a nominal voltage to earth not exceeding 300 V. The outgoing circuits contain short-circuit protective devices, each having a rated current not exceeding 125 A with a total incoming load current not exceeding 250 A.

Although no longer current it seems BS EN 60439-3 is cited in building regulations and there has been some talk about if EICR should highlight the use of an unit when although not permitted under amendment 3 soon it is still the standard quoted in the building regulations. Sorry I had missed this, I had just not considered it when first answering the post.

 

[davelx]

It makes no difference being three phase or single phase or split phase with a shock line to earth. In all cases it's 230 volt.

Are you sure about that? Isn't the RCD's CB transformer/sensor measuring the imbalance between phase and neutral currents? In which case would it not trip on a phase-phase shock as well as phase to earth, as the phase current would not be returning via the neutral in either case?

All phases and neutral all go through the same current transformer so as long as that is the case the shock phase to phase or phase to neutral will not trip a RCD. Where the neutrals or phases are split as with a RCBO then any connection between either phase or neutral be it the same or different phase with either phase or neutral which is not going through the same RCBO will trip it. So yes if you fit three RCD's one for each phase then phase to phase connection would trip the RCD device, but then no point having a three phase supply as one could not use it as a three phase supply.

I think he meant single pole RCBOs on different circuits. Or RCDs on different phases. A P to P fault would then trip the RCD.

Yes - as might be found in a domestic installation with CUs on different phases (per JohnW2), rather than 3ph RCDs in a commercial 3PH DB.

 

[PBC_1966]

Well the ETCI Wiring Rules (ET101) still requires a warning notice if 400V exists between accessories (which used to be common in installations designed and constructed to the IEE Wiring Regulations.

Thanks. And presumably also still required for 400V within a single enclosure, such as a switch bank? With or without some stipulation about "normally expected" there?

Are there still - or do you know if there existed in the past - similar rules to the IEE Regs. about sockets on different phases or poles in the same room?

Put a notice on the sockets in the old way. i.e. Yellow dot, Blue dot, Red dot and the number of the MCB feeding it. If modern then Brown, Black and Gray dots.

I've seen a couple of places where they went rather overboard and painted the entire face of the sockets red, yellow and blue.