Wiring Regs. - 17th Edition - rumour confirmed?

[Andy Wade]

I notice that the NICEIC have recently updated their note about the major changes between the 16th and 17th editions:

(file created 1st November).

Rumours regarding changes to regulation 522.6.6 of the public draft edition appear to be confirmed - to quote:

"The requirements relating to cables concealed in a wall or partition have been altered so that protection by a 30mA RCD is an additional requirement for ?unprotected? cables (e.g. twin and earth cables installed in a chase less than 50mm deep); it must be emphasised that such cables must still be installed in ?safe? zones."

[Andy Hall]

So do you read the implication of this as being 30mA RCD protection for all circuits regardless of where the cables are run? i.e. even in the 150mm safe zones? This implies whole house RCDs or RCBOs.

[Andy Wade]

In effect, yes. What it appears to mean is that if you want to run a non-RCD-protected circuit then the cables must either

- be one of the prescribed types which incorporate an earthed armour, screen or covering, or

- be run in earthed metal conduit, or

- be buried deeper than 50 mm in a wall, or

- be wholly surface-wired.

Or multiple RCDs, or some combination of RCDs and RCBOs.

[Andy Hall]

I haven't seen anything for interior use that fits this bill. Surely not SWA?

implies a lot of labour

which can't be done in a modern domestic property.

which won't be aesthetically acceptable

I think that I might go and buy some Honeywell shares (as in MK) .......

[dom]

I think we're about to see a big ramp-down in the price of RCBO's (as there's nothing particularly expensive materials wise or rocket science about the technology in them) and for the manufacturers to launch CU's pre-populated with RCBO's at a much reduced bundle price.

[Andy Hall]

Consumer units will need to be redesigned though - e,g, the busbar arrangements, I would have thought ,because of the extra connections.

[Andy Wade]

That's one option. The full list is:

- BS 5467 - SWA (XLPE/PVC)

- BS 6346 - SWA (PVC/PVC)

- BS 6724 - SWA (XLPE/LSF)

- BS 7846 - SWA (XLPE/OHLS)

- BS 8346 - e.g. 'Earthshield' [1]

- BS EN 60702-1 - MICC

[1] See I think that I might go and buy some Honeywell shares (as in MK) ....... Might not be a bad idea...

[Owain]

Don't the French use double-pole MCBs or RCBOs in their consumer units?

So handy for isolating le s*n*f*o ...

Owain

[Andy Hall]

not mechanical protection but rather that it is assumed that someone driving in a nail will reach the CPC outer screen first and will then hit a phase conductor, thus tripping the MCB?

[Frank Erskine]

Sod that. Good job I used my old 4mm cooker radial circuit as a non-RCD-protected circuit for the fridge-freezer. It shouldn't need rewiring for a decade or two...

[John Rumm]

Once solution here would seem to be to treat all installs as we currently would a TT one. That way one can still have "non protected" (i.e. 100mA or higher trips thresholds and time delays) on circuits where appropriate.

[Andy Wade]

How would that help? 100 mA and/or time-delayed RCDs will not meet the

30 mA / 40 ms requirement [in 415.1] for additional protection.

[Andy Wade]

And here's the ECA's contribution:

[John Rumm]

Missed that bit... obviously it wouldn't

30mA trip seems excessive if the only intention is to protect the wiring itself and against indirect contact risks (or whatever the new phrase is) - especially on lighting circuits.

[Robin]

where please?

[fred]

I'm sure Pirelli has carried out tests but I wonder what the chances are of the foil vaporising in an annulus around such a nail before a 32A breaker trips?

When Mr W first raised this issue I assumed that everyone would just move over to non-split CUs with everything on the trip or add an RCD to the previously non-RCD side in retrofit, this would be far less than the cost of specialist cabling and IMO it is cost that will drive this market.

[Andy Burns]

Dunno, but surely the intention of the 17th Ed. is that there is no worry about an MCB having to trip because an RCD (or RCBO) will do instead?

[Andy Burns]

definition of ...

"A person who possesses sufficient technical knowledge and experience for the nature of the electrical work undertaken and is able at all times to prevent danger, and where appropriate, injury to themselves and others."

At _ALL_ times?

[fred]

IIUC the Pirelli is designated as a protected cable and so does not require to be on an RCD protected circuit.

[John Rumm]

Which looking at the bright side, is actually a definition of competence that most would recognise, an does not (yet) include requirements to belong to any particular trade organisation.