Toolbox: Power cords

As you are no doubt aware, electricity - both mains power 240V AC and vehicle 12V DC (24V DC in some trucks) - plays a major part in the RV lifestyle. Now, for the most part, extra-low voltage 12V DC usually suffers from loose connection and high resistance faults rather than any safety issues, but 240V AC is another matter altogether and a great deal of regulation, mostly from Australian Standards 3000 and 3001, covers all electrical installations.

In most RV 240V setups, there are essentially three components - the 15A power outlet that belongs to the caravan park or whoever, the 15A (usually) power lead and the RV itself. The caravan park outlet should be in a safe condition and is the responsibility of the caravan park.

Electrics in the RV should have been signed off by a licensed person in the first place and unless something is changed or has a fault, then there is not much that can go wrong here (although we would recommend having a licensed person check over a second-hand purchase, particularly in older rigs).
 
However, the bit in the middle, the power cord, is often vulnerable to physical damage and is also where most safety problems and accidents occur.

TECHNICAL REQUIREMENTS
Within the last 10 years there have been a number of changes in power cord requirements. Generally speaking all RVs require a 15A power cord. A 15A cord is easily distinguishable from the normal rating of 10A by looking at the plug. On the 15A plug, the earth pin is considerably wider than one on a 10A socket. Apart from anything else, this means a 15A cord cannot be used in a normal 10A socket.

We should point out that we are aware that hidden away in many a caravan and motorhome are very short extension cords that have a 10A plug on one end and a 15A socket on the other for occasions when a 15A socket is not available, like at home. Technically these are not legal but do get used for things like charging up the house battery or cooling the fridge prior to a trip. In any event, they should not be used for any current that exceeds 10A.

In case you do not have an ammeter handy, the latter can be from high energy devices like an electric kettle or air-conditioner. Remember the formula, Watts = Volts x Amps, so if you have 10A and 240V and the device (or devices put together) is more than 2400W, you're in trouble.

You can use 10A power cords but there are a few restrictions. The length cannot exceed 10m unless a 1.5sq mm conductor is used, and the inlet socket on the RV and the circuit breaker must be rated at 10A only.
For 15A power cords, Australian/NZ standard 3001 specifies that four lengths can be used as per the table below.

The reason for the increase in cross-sectional area is to do with the fact that increased length causes voltage drop, and low voltage will result in dimmed lights but more seriously, damage to items like fridge motors.

If you're contemplating a 40m cable, keep in mind that it can be both expensive and heavy to carry!

POLARITY
This subject is not often mentioned but is sometimes a problem with home-made electrical cords. It's caused by the active and neutral leads being reversed in either the plug or socket of a power lead. In years gone by the active lead was coloured red and the neutral lead black, and there was possibly less confusion than when a change was made to the universal standard and the active lead became brown and the neutral blue. In all cases the earth lead was either green or green and yellow.

The problem with reversed polarity occurs in (mostly older) RVs with only single-pole switching (ie, of the active lead) and the possibility that the neutral will be "live" despite being switched. In any RV with double-pole switching (as required by present regulations) - ie, both active and neutral leads are switched - this is not such a problem.

CARE AND MAINTENANCE
Given that power cords are subject to a fair bit of mechanical abuse, there are a few things to keep in mind. The first is that they should be inspected regularly. Both plug and socket should be checked for heat damage. Yes, that can occur and is evident by melted plastic. The outer sheath of the power cord should also be checked to ensure that the inner cores are not exposed at either the plug or socket. The simplest way to fix that is to remove the plug or socket and shorten the cores. Or, if it is a sealed plug/socket, get a new one fitted.

If the outer sheath has been damaged along the power cord, then electrical insulation tape can be used in the short term but a long-term solution is either a new cord or removal of the damaged part and a shorter cord.

One of the disadvantages of a visual-only inspection is that it does not show any weakness in the electrical insulation of the power cord. That can only be achieved by having the cord electrically tested, and these days, that process is known as "tagging and testing".

A qualified person can test a power cord quite quickly and then it's tagged to show the date of the test. Under occupational health and safety requirements, all commercial premises (including caravan parks) are required to have all their power cords tagged and tested but as far as we know there are no legal requirements on the RV owner.

However, given the use that RV cords get, that does not mean it is not a good idea.

AT THE CAMPSITE
When electrical cords are being used, there is often a temptation to coil any excess cord up neatly. This is not a recommended practice, mainly because heat can be generated in the cord when it's being used, and if tightly coiled up, then natural air cooling won't be particularly effective. A better idea is to lay the cord on the ground under the RV, out of the way of being tripped over.

Another no-no is to have power cords dangling from power outlet posts or trees in such a way that they can be tripped over or get tangled around someone's neck. You might laugh but we've seen it happen.

STORAGE
When packing up power cords, the easiest way is just to loop them up and throw them in the nearest storage bin or caravan boot. We'd like to suggest that a better way is to use something like a Flat Out or similar storage reel.

That way the power cord is neatly wound up, easily stored, won't get tangled in anything else and is reasonably protected against mechanical damage.

FINALLY
This might sound like a grim warning but electrical cords are responsible for more electrical fatalities than just about anything else. There is no substitute for taking care.