Historically, electrical regulators laid down what must
be used, where and how. Increasingly however the obligatory use of safety devices
such as circuit breakers (that limit excess current) and RCDs (residual current
devices that disconnect electrical supply in event of certain faults) enables
a shift from prescriptive requirement. Now, there is a global move to allowing
alternative approaches proven to be safe. This is reflected in the new joint Australian/New
Zealand Standard AS/NZS 3001:2001 - Electrical installations - relocatable premises
(including caravans and tents) and their site installations. This Standard also
covers campervans, motorhomes and annexes. The changes that affect motorhome users
mostly relate to supply cables, but there are many other requirements that installers
and repairers need urgently to study. Preparing this article required close and
ongoing consultation with Standards Australia and also an Energy
Safety Authority. The former required that any comment be published as
provided. I regret that some parts of this feature may not be fully clear to people
lacking a technical background in this area. It will however be understood by
licensed electricians and I have provided the necessary references to enable them
to locate the further information they will need. Because these regulations are
both recent and very comprehensive, members are likely to find that not all licensed
electricians are yet aware of the implications (and some I fear are not even aware
that the regulations have changed). In light of this I strongly recommend that
Members likely to need electrical work retain or copy this article and show it
to the electrical contractor concerned.
Australian caravan parks that provide mains electricity have,
for some years, been legally required to install safety-protected 15-amp outlets.
It is now permissible to use an outlet of another rating or configuration . for
specific anticipated types of relocatable premises 1 . In practice however caravan
parks will continue to provide service pillar mounted 15-amp outlet sockets, circuit
breakers, and residual current devices.
It is now permissible,
subject to the requirements and restrictions set out below, to use a 10-amp supply
cable up to 25 metres long. This is a welcome change as it also enables a vehicle
to be plugged into a 10-amp outlet socket. "The simplest way to connect a
motorhome or similar to a 10 amp outlet of any kind is to arrange for the appliance
inlet on the motorhome to be a 10 amp appliance inlet (rather than the usual 15
amp unit) and for the load limiting device on the motorhome to similarly be 10
amps" 2. The latter requirement (load limiting) is described below .
1 in this article sets out the maximum and minimum supply cable lengths, and the
minimum cable conductor sizes 3. The longer the cables, the heavier that conductor
must be, but it is both sensible and legal to use heavier cable for the shorter
lengths. It is also permittable to fit approved 10-amp plugs and sockets to '15-amp'
cable (such cables are already on sale). Existing (approved) 15-amp, 30-metre
leads may still be used. Only one cable may now be used: you must not interconnect
supply cables to extend reach. 4
Minimum Cross Sectional Area of Lead Conductors
Maximum Length of Lead (m)
Table 1. Maximum permissible supply cable lengths and
required (minimum) conductor sizes.
This is Table 5.1 in AS/NZS 3001:2001.
the Supply Current
The ability to use a 10-amp plugged cable is welcome,
but this change, if applied alone, would allow 15 amps being drawable via a cable
and/or plug designed for only 10 amps. To preclude this, the eminently sensible
requirement is that if the supply plug is rated at 10 amps, then there must be
automatic provision to prevent more than 10 amps being drawn. Replacing the vehicle's
existing 15-amp circuit breaker by a 10-amp device is one obvious and acceptable
It is now
legal to have the vehicle inlet also 10-amp rated provided the inlet socket rating
(ampere) meets the maximum demand (ampere current rating) of the vehicle. That
inlet must have not lower than IP24 protection (electricians know what this means)
5 . Currently the only approved 10-amp inlets appear to be surface-mounting IP56
rated, but no doubt conventional flush mounted units will become available.
workable and legal alternative is to do away with the inlet socket altogether
by having the supply cable (of any size or length that complies with (our) Table
1 permanently connected at the vehicle end and housed within the vehicle in an
enclosure of specified form when not in use 6 .
Amp Plug/Cable - Fifteen Amp Inlet
It is also now possible to retain
the 15-amp inlet and 15-amp supply capability but to use a special cable that
limits supply to 10 amps (see below) when it is required to make a power connection
where only a 10-amp outlet is available. The normal approved 15-amp cable is then
used at all other times.
The Energy Safety Directorate
(of the WA Department of Consumer and Employment Protection) advises that whilst
a flexible cord with a 15-ampere socket outlet and a 10-ampere plug top is not
If the cable is protected by an external 10-ampere
overload device with combined RCD and maximum demand does not exceed 10 ampere
then this arrangement would be acceptable.
In other words the
cable assembly automatically limits current to 10 amps and thus provides its own
protection. Where the full 15-amp circuit capacity is required an approved 15-amp
cable must be used. This 'self-limiting cable' is thus used only when circumstances
Standards Australia notes that: "such a device might
be available as a ready-built unit (including units designed for use as outlet
boxes on show and carnival sites and complying with AS/NZS 3002:2003".
It also advises that such a device might be constructed from proprietary components
by a licensed electrician "who will ensure that the rating of the components
and the enclosure are appropriate for the circumstances in which it will be used
and comply with electrical principles . . . [the electrician] will also decide
if consultation with the State electrical safety authority is appropriate."
In other words, the 10-amp cable has a special plug or socket that
incorporates a built-in 10-amp circuit breaker (and perhaps an RCD). These devices
are commercially available (from electrical wholesalers - but not hardware stores)
but they must be assembled as a cable by a licensed electrician. Their maximum
length must be 25 metres. No alternative enables a 10-amp supply cable or outlet
to supply a 15-amp circuit load. And nor it should - it cannot safely be otherwise!
Fortunately this unfulfillable 'need' will only normally arise in either of two
1. In homes with only 10-amp outlets. The only solutions
are to have a licensed electrician install a 15-amp circuit and supply outlet;
or to use the special 10-amp current-limiting cable described above.
At caravan parks that only have 10-amp outlets. You should move on, or forgo mains
power as it's odds on that obligatory safety devices are not installed either.
This leaves users at risk as these safety devices are now relied upon to provide
safety protection in otherwise potentially lethal fault conditions.
recent changes have removed some anomalies but have increased complexity. It is
now even more necessary to stress that caravans and motorhomes are more potentially
dangerous electrical environments than are houses. Further, there are many differences
in their wiring, circuit breakers, RCDs, switches and power points. You must have
work done by an electrician licensed by the State in which that work is being
done. It is still legal for a competent person to make up basic supply cables
for their own use only 9 , (but not the specialised self-limiting cable described
above). However, electricity authorities, the CMCA Safety Committee, and the author,
strongly recommend you have a licensed electrician do it for you - or at least
check your work for compliance and safety.
Whilst there is now a combined Australia/New
Zealand Standard, there are a few but profound differences between our electrical
practices. If using an RV made in one country but used in the other it is vital
to have a licensed electrician check the wiring for compliance. Most vehicles
will require one absolutely essential change. For New Zealand vehicles used in
Australia, there may be others. (Show the electrician the note re this at the
end of this article).
new regulations only partially address the connection of generators that are supplied
with 10-amp outlet sockets (that cannot be changed to 15 amps without invalidating
warranty). A 10-amp cable may now be used subject to the vehicle being limited
to 10 amps draw, or to use a 10/15 amp self-limiting cable as described above.
This is probably not a serious restriction. Most users requiring a 15-amp service
will have a 15-amp generator. If you don't, then change the inlet etc.
Australian 'Standards' are only 'Recommendations' until and
if adopted by State Regulators: " Australian Standards only become law if
a relevant body says so," note s Standards Australia . There is thus a lag
between a Standard being published and becoming law. This made it impracticable
to publish this article until all States had adopted the new rules because, until
then, the existing Standard applied - hence my sometimes-guarded responses to
recent enquirers. Some of the implications are only surfacing now and because
of their newness, scale and complexity not all electricians may yet be fully aware
of all of the implications.
author thanks Australian Standards, the Energy Safety Directorate of Western Australia,
and CMCA Member Ian Bond for assistance in preparing this feature. This article
reflects my own current understanding based on a close study of the relevant Standards,
and direct correspondence to and from Ian Bond and myself with the above authorities.
I must emphasise that whilst I have taken considerable care to ensure the accuracy
of this article and have an extensive background in research and electrical engineering,
I am neither a licensed electrician nor a professional electrical engineer. This
article is limited to an overview of what seems to be possible. I do not accept
any responsibility for its accuracy excepting that the relevant authorities have
provided the credited quotations with their knowledge that they would be published
herein. Those professionally concerned with this matter should study the AS/NZS
3001:2001, and AS/NZS 3000:2000 (plus recent Amendments). Any decision or work
relevant to this matter should be made and/or done by a licensed electrician.
NZ practice is for
Earth and Neutral to be bonded within the vehicle - as with normal domestic practice,
but not RV practice, in Australia. This link must be removed if the vehicle is
used in Australia otherwise reversed polarity will impose 240 volts on the chassis
etc of the vehicle. Australian RVs also use double-pole circuit breakers, RCD,
and switching throughout.
AS/NZS 30001:2001 Section 22.214.171.124.2
2. Direct communication from Standards
3. This is Table 5.1 in AS/NZS 3001:2001
4. Section 5.1.1 of
5. Section 3.2.1 (iv) of the above
6. Section 3.2.2 of the above
Direct communication from Energy Safety Directorate (WA) 22 December 2003.
Direct communication from Standards Australia
9. As (6) above, and also confirmed
by Standards Australia
Rivers W 8054 (copyright 2005)
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