RV supply cables – choices of current capacity and length

by | Jul 15, 2020 | Articles, CME, Electrical (general), Health & Safety, SRW

by Collyn Rivers

RV Supply Cables

This article shows the sizes and lengths of electric supply cables for RVs legally required in Australia and New Zealand.

RV supply cables – the basic requirements

Prior to 2008, some restrictions on RV supply cables ensured they were acceptable for other usages then under revision. Without those restrictions, supply cables would have been legal (and safe) for some uses, but not others. The revised requirements thus removed that risk. Furthermore, they resulted in a greater choice of approved lengths.

The new RV supply cables requirements are set out in Table 5.1 of AS/NZS 3001:2008 (as Amended in 2012). These requirements are still valid (July 2020).

The most relevant part is set out below. The lengths and sizes shown relate to typical supply cables for all RV and general use. There are, however, restrictions if used for loads such as large electric motors etc.

Cable ratingConductor areaLength
10 amp1.0 mm²25 m
10 amp2.5 mm²60 m
10 amp4.0 mm²100 m
15/16 amp1.5 mm²25 m
15/16 amp2.5 mm²40 m
15/16 amp4.0 mm²65 m
RV supply cables (and general use). This is Table 5.1 of AS/NZS 3001:2008 as Amended in 2012. Extract reproduction by courtesy of Standards Australia.

Thou shalt not join cables together

There is an overall purpose behind specifying lengths and conductor sizes of supply cables. It is to ensure circuit breakers operate within that vital 0.4 seconds. To save a human’s life against electrocution, that short time is critical. Co-joining cables slow down the circuit breaker’s operation.  That’s why joining supply cables end-to-end is so dangerous. It is also seriously illegal.

Supply cables must thus be one of the approved types and of one unbroken length.

10-15 amp adaptors

The restriction on co-joining cables applies also to 15-10 amp adaptor leads. These (illegally) enable 15 amps to be drawn through cable too thin to do so. Here again, doing so slows tripping of the associated circuit breaker. It may not trip in time to save a life. The Ampfibian 10-15 amp adaptor (described below) is legal. It restricts current flow from a 15 amp source, to 10 amps.

Never use a double adaptor to enable another travel trailer to share the socket outlet. This has always been dangerous. It is now illegal. If someone plugs your cable into a double adaptor, attempt removal amicably. If that fails, insist the park manager removes it for you.

The above requirements are not hard. Your supply cable must comply with the standard. You must use only one cable to connect your vehicle to the supply. If it is too short, obtain a longer one, or move the travel trailer closer. The only otherwise alternative is to forgo using that site’s power.

None of the above is negotiable. The requirements are clear and legally mandatory. Personal and forum ‘opinion’ is irrelevant.

How protective devices work

Supply cable rules take into account so-called Residual Current Device (RCD) and circuit breaker protection. An RCD compares the current flowing in both active and neutral leads. If imbalanced it is likely to be via a human to earth. The RCD should detect this and cut the current flow accordingly.

Circuit breakers monitor for excess current flow. They cut the current if an excess is detected. They primarily protect supply cables and appliances. Their effect is similar to fuses – but are more reliable.

10/15 amp issues

Early travel trailers used appliances that drew more current than now. That required travel trailer parks to have 15 amp socket outlets. You may, however, need to use a travel trailer where there are only 10 amp outlets. A 15 amp plug will not fit. It has a larger earth pin. Some people file down that pin to fit. Or make an illegal 10-15 amp cable. There cannot however be a weak link in a chain of safety. That includes not pulling 15 amps through plugs, cables and connectors designed to carry 10 amps. It’s like a 15-tonne winch with a 10-tonne cable.

You can, however, legally use a 10 amp supply cable for travel trailers if all related bits are also changed to 10 amps. That includes the inlet socket, RCDs and circuit breakers. Doing so thus prevents over 10 amps being drawn. Clipsal now has a 10 amp socket inlet that directly replaces the 15 amp unit.

The Amp-fibian

The Amp-fibian is a legal alternative. It is a short cable with a 10 amp inlet plug. It also has an inbuilt 10 amp circuit breaker and RCD. Plus a 15 amp outlet socket. It restricts supply to 10 amps but as most electrical appliances now draw less energy this not likely to be a problem.

RV Supply Cables. AMP-FIBIAN Products

The Amp-fibian 15-10 amp adaptor. A standard 15 amp supply cable is plugged into the receptacle (left) that is then sealed by a waterproof cover.

If seeking to power an RV at home, you can use that adaptor – or have a licensed electrician install a 15 amp power outlet socket.

The RV supply cables requirements apply now also to their general use.)

RV Supply cables – tagging

Occupational Health, Safety and Welfare Regulations include provisions for protecting staff. These include regularly inspecting and testing electrical equipment and supply cable. This latter activity is known as ‘tagging’. It generally enforced by travel trailer parks and RV rally organisers.

That it is needed was typically shown by a travel trailer club meeting in 2014. There, of 212 supply cables tested, 84 (40%) failed to pass. Five had broken earth wires within the plug or socket. Twenty-four had neutral and active conductors incorrectly connected – a total give-away of having illegally made one’s own cable. (The standard re-testing is AS/NZS 3760).

[caravan park] owners and managers, and rally organisers, are responsible for employee safety. There is also a general duty of care for those staying or visiting.

None of the above legally requires users’ cables to be tagged. Some travel trailer parks, however, enforce it. There is currently no legal requirement for them to do so. That may, however, be conditional for insurance cover. A travel trailer park can, however, enforce this as a condition of entry.

For cable taggers – check local Yellow Pages (or Google).

Outdated standards

Long-retired electricians may not be aware that fundamental safety approaches have totally changed. This, particularly, is true of earthing. Source documents are: AS/NZS 3000:2018, and the RV-related AS/NZS 3001.2008 (Amended in 2012).

Legal Disclosure

The above is sourced from Standards Australia’s documents (noted above)) I have an extensive practical and theoretical background in high voltage electrical equipment and systems. I am not, however, a qualified electrical engineer, nor a licensed electrician.

Further information

Further details about supply cables for travel trailers etc, is in Caravan & Motorhome Electrics, Caravan & Motorhome Book, and the Camper Trailer Book. My books on solar are Solar That Really Works (for cabins and RVs) and Solar Success (for home and property systems).

Collyn Rivers is a semi-retired automobile research engineer.  He is the author of seven books, five of which are about making RVs and solar work optimally.

Caravan and Motorhome Electrics

The essential handbook for anyone with an RV of any kind.  Everything you need to know to make the electrics in your rig work for you.

Cover of Caravan and Motorhome Books by Collyn Rivers

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of Caravan & Motorhome Electrics.  Just ask.
ISBN: 978-0-6483190-8-5

Solar Success

Whether you’re building a new home or adding solar to an existing structure, this is the one book you can’t afford to be without.

eBook versions

Paperback version

Any bookshop, whether online or bricks and mortar, can order copies of Solar Success.  Just ask.
ISBN: 978-0-6487945-4-7

Why Caravans Roll Over
and how to prevent it

Explains in detail every aspect of tow vehicle and travel trailer stability. This is what you need to know to be safe on or off the road.

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of Why Caravans Roll Over.  Just ask.
ISBN: 978-0-6483190-6-1

Solar That Really Works!

Solar that Really Works! covers the design, installation and use of solar in cabins, camper trailers, travel trailers, fifth wheelers, campervans and motor homes.

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of Solar That Really Works!  Just ask.
ISBN: 978-0-6483190-3-0

The Caravan & Motorhome Book

The Caravan & Motorhome Book covers every conceivable aspect of campervan and motorhome usage. If you own a camper van or motor home, you'll want this book.

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of The Caravan & Motorhome Book. Just ask.
ISBN: 978-0-6483190-5-4.

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Caravan and Motorhome Electrics

The essential handbook for anyone with an RV of any kind.  Everything you need to know to make the electrics in your rig work for you.

Cover of Caravan and Motorhome Books by Collyn Rivers

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of Caravan & Motorhome Electrics.  Just ask.
ISBN: 978-0-6483190-8-5

Solar Success

Whether you’re building a new home or adding solar to an existing structure, this is the one book you can’t afford to be without.

eBook versions

Paperback version

Any bookshop, whether online or bricks and mortar, can order copies of Solar Success.  Just ask.
ISBN: 978-0-6487945-4-7

The Caravan & Motorhome Book

The Caravan & Motorhome Book covers every conceivable aspect of campervan and motorhome usage. If you own a camper van or motor home, you'll want this book.

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of The Caravan & Motorhome Book. Just ask.
ISBN: 978-0-6483190-5-4.

Solar That Really Works!

Solar that Really Works! covers the design, installation and use of solar in cabins, camper trailers, travel trailers, fifth wheelers, campervans and motor homes.

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of Solar That Really Works!  Just ask.
ISBN: 978-0-6483190-3-0

Why Caravans Roll Over
and how to prevent it

Explains in detail every aspect of tow vehicle and travel trailer stability. This is what you need to know to be safe on or off the road.

eBook versions

Paperback version

The book retailers set their own prices which can vary substantially. We'll aim to keep a selection of the better prices above.

Any bookshop, whether online or bricks and mortar, can order copies of Why Caravans Roll Over.  Just ask.
ISBN: 978-0-6483190-6-1