NZECP1:1993 allowed the use of RCD’s in caravans but not caravan parks, this was because a MEN link was still required in the caravan.
There was a further change of rules when AS/NZS3001:2001 became the cited standard for connectable installations. This required protection by RCD for sockets on supply pillars except for the IEC60309 (Blue Sockets). Still due to the MEN link in the caravan. RCD protection was required for all sub circuits of the caravan installation.
AS/NZS3001:2008 moved things along again requiring RCD’s for all Supply pillar sockets and deleted the requirement for any MEN link in connectable installations that have a plug and socket connection to the supply.
The evolution has been a slow and steady one and has followed along with the development of the electrical industry’s equipment.
The rules are changed to allow the use of new equipment that enhances safety.
I have taken the liberty of posting the text of ESR113 which is the grandfather clause that allows existing electrical installations to remain in service.
113 Existing and in-process works, installations, fittings, and appliances
(1) This regulation applies to works, installations, fittings, and appliances that, on 1 April 2010, were—
(a) installed, for sale, or in use in New Zealand; or
(b) under construction or being installed in New Zealand; or
(c) in transit to New Zealand; or
(d) the subject of an irrevocable purchasing order by a person in New Zealand.
(2) Despite anything to the contrary in these regulations, the works, installations, fittings, and appliances—
(a) may continue to be constructed, installed, sold, or used provided that—
(i) they are not electrically unsafe; and
(ii) they complied immediately before 1 April 2010 with the require- ments of the Electricity Regulations 1997; and
(iii) they continue to comply, as a minimum, with the requirements of the Electricity Regulations 1997 as in force immediately before their revocation by these regulations; and
(b) may, until 1 April 2012, be tested, certified, or inspected in accordance with—
(i) the Electricity Regulations 1997 as in force immediately before 1 April 2010; or
(ii) these regulations.
The key words in there are “Electrically Unsafe”
If every change to the electrical rules mandated compliance with the latest rules you would need to have an electrician on speeded dial and it would be prohibitively expensive.
There has only ever been one change to the Electrical rules that was retrospective in that it banned the use of something that was established in common usage. This was the rule that banned the use of scraping earths and effectively outlawed the old style reyrolle plugs and sockets.
Hedley Berge
Electrical Inspector