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Posted By Topic: Caravan refit - flex and combined DB

GPower
Jan 10 2018 15:28

I have a client that asked me to come and replace some sockets in his imported (UK) caravan. He has supplied the sockets square HPM ones so I asked for an SDOC but he had none and said the last company didn't require one. The wiring was all in in un-protected but clipped flex (doesn't look HD but not sure how to tell, I would of thought additional insulation?) BlGBr colouring. I checked 3001 and it mentioned you can use flex but no mention of colouring. I looked at 3.9.7.4 of 3000 and the exceptions and was still unsure if it is OK to connect (maybe with sleeving). I looked at the DB as he had supplied an RCBO to change over and there is a combined ELV DC and 240v DB with little segregation and the remaining MCB's are double pole switching the N as well. He said that he had another company do the same a week ago to another van as I was off work and an inspector sign it off (from same company). In a waterproof well on the side was a non waterproof socket with a what looked like a white computer plug joining the flex which could be removed and re terminated. I said I would not connect as I was wanted to do some more research into this and he was happy to take it back to the other company so I walked. For the hour or two's work with the gear that he supplied I did not think it was worth the risk. What would your thoughts be on the above as far as compliance if there was another situation like this?
   

pluto
Jan 10 2018 18:11

There are some changes coming for certification overseas caravans built to IEC 60364-7-721.
(mainly from Furope) In fact many comply with very light remedial work being required.

An accouncement will be made soon via the usual trade information channels.
   

AlecK
Jan 11 2018 09:59

there are a lot of issues here; but the first thing to note is the requirements of ESRs for issue of a WoEF. It is NOT required that every aspect of an imported caravan / motorhome comply with rules for building a new one (AS/NZS 3000 + AS/NZS 3001). A normal WoEF is issued after checking the items listed in Appendix c of "3001", and that list allows for older NZ-built units to be issued WoEF without being forced to upgrade to latest requirements for new. This amounts to a practical application of ESR 113, where things that were OK when installed can remain in service. So there is no requirement to have the unit comply with the main body of "3001", it only has to comply with the matters listed in App C.

For an imported caravan, the unit first has to be assessed for compliance with Part 1 of "3000". These are the fundamental safety rules, not the detailed requirements of Part 2 which most of us are more familiar with. Unfortunately, the quality of these "Part 1 assessments" varies a lot, as shown by units that have been issued a WoEF in the past but which have significant issues. There's also the fact that this rule only came at beginning of 2012 (via ESRs amendment 2011), so units imported earlier never got any such checks. And there are those who think this assessment only happens once, when first imported; whereas what the ESRs call for is a Part 1 check EVERY time.

So for an Inspector to reject something, they have to find either a rule of Part 1 that has been broken; or a requirement of App C that has not been complied with. Just a feeling the "that's not how I would like it done" is NOT enough.

For the specific items mentioned:
SDoC for sockets. The requirement for SDoC applies when sockets are sold or supplied in NZ. There is NO requirement for an installer to sight, let alone have a copy of, an SDoC. The issue for installers is: are the sockets electrically safe? If so, you can certify your work. If you don't feel competent to make this assessment, you really shouldn't be a sparky because SDoCs only cover a tiny fraction of the fittings you will need to install & certify in your career.

In fact there's no specific requirement to change the UK style sockets to NZ type; but it certainly makes sense to do so for GPOs.

Use of flex.
Nothing in Part 1 prohibits use of flex as installation wiring. The requirement for such flex to be HD is in Part 2, so does not apply. Same for colour ID of cores. And since you're not installing the flex anyway - it's already there - it doesn't get covered by your ESC for changing the sockets. Use of sleeving would be good practice, but it is not a "domestic installation" so ESR 20 doesn't require black for N (and equally the "homeowner" exemption does not apply).

Of course cabling has to be protected against mechanical damage, but the details of that vary with circumstances. Cable along a wall / floor corner under a bunk needs less than cable across the underside of the floor.

RCD
The existing RCD will almost certainly be Type AC, and so needs to be changed to Type A. This is in App C, not Part 1.
It is generally also the main isolation switch for the caravan; so if a 16 A /30 mA RCBO is swapped in that covers the current limitation requirement as well as RCD protection of all final subcircuits.

MCBs
The 2-pole mcbs are perfectly OK, because the RCBO is also now serving as overcurrent protection for the subcircuit cabling, making the mcbs effectively just termination points. There nothing even in Part 2 or main body of "3001", let alone Part 1 + App C, that prohibits switching of subcircuit Ns; and in fact it can be a good thing for isolating earth faults so the RCD doesn't trip.

Segregation within switchboard
Again you need to be looking at Part 1 rather than Part 2; many of these combination LV / ELV switchboard / chargers are OK, but some aren't.

Many UK caravans have the white "plug & connector" joins, because the wiring loom is pre-made and then all the fittings and appliances are "plugged-in" at a later stage; all assembled by unskilled labour.
The points to consider include
- can the connections be undone without use of a tool, and does that give touch-access to live parts?
- are unsheathed cores of cables accessible (if so an enclosure may need to be fitted over the connection).

Something else to consider is that while a normal electrical installation excludes any appliances, for a connectable installation appliances are specifically included. Which makes the Inspector issuing WoEF responsible for things like water heaters, space heaters, fridges & microwaves whether plugged into sockets or "direct connected" by those wee white connectors.

While Part 1 takes some getting used to, Inspectors should be competent to work in that space. The only way to become familiar is to go though it carefully. On the other hand, never accept something just because someone else did. If you don't think something is right, find a rule to support your feeling. If you can't, maybe it's your feeling that needs to change.