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The perils of a coiled power supply cord

Arthur How

It has come to my attention that some caravanners are connecting a 230 volt power supply, via a lead, that is “coiled on a reel”, which is not completely “uncoiled” from the cable drum.

This is not good practice, as the cable, when supplying power to a caravan or any appliance, is carrying voltage & current, which will create a “magnetic field” around the cable conductors.

When a cord or cable, is coiled on a drum, the magnetic field is stronger and more intensely concentrated, which in turn, can cause a “transformer effect” and load up the cables which then run at a higher temperature, stressing the insulation of the 230 volt supply cable to the motorhome/caravan (or appliance).

Image and text: ©2024

Magnetic Field Around a Wire

Whenever current travels through a conductor, a magnetic field is generated.

A magnetic field is created anytime current runs through a conductor. A fact famously stumbled upon by Hans Christian Ørsted around 1820. MORE:

Image and text: ©2024

Completely unwind the cable from the cable drum when you plug it in to power to avoid this overloading, cable stress and it running at a higher temperature.


Arthur How is a Registered Electrical Inspector and does EWOF inspections in Foxton, Manawatu. 


don't do it

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