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 rating | Conductor area | Length |
|---|---|---|
| 10 amp | 1.0 mm² | 25 m |
| 10 amp | 2.5 mm² | 60 m |
| 10 amp | 4.0 mm² | 100 m |
| 15/16 amp | 1.5 mm² | 25 m |
| 15/16 amp | 2.5 mm² | 40 m |
| 15/16 amp | 4.0 mm² | 65 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 caravan 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 caravan 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 caravans used appliances that drew more current than now. That required caravan parks to have 15 amp socket outlets. You may, however, need to use a caravan 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 caravans 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.
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 caravan parks and RV rally organisers.
That it is needed was typically shown by a caravan 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 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 caravan parks, however, enforce it. There is currently no legal requirement for them to do so. That may, however, be conditional for insurance cover. A caravan 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 caravans 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).
