Fitting a USB socket to a positive ground T Type

Paul Ireland writes on fitting a USB socket to his TC and the importance of fusing it.

Paul Ireland finds that using modern computer stuff in his TC is extremely useful: stuff such as the satnav on mobile phones, a dash camera and the like make driving much easier than wrestling with large and folding OS maps. But then how do you keep them charged? The perennial question of everyone who uses such devices …

The obvious answer is to fit a USB socket to your T Type but of course there’s a problem in that these things are designed to be used in negative earthed cars, whereas most T Type owners have kept their car as positive earth. So the important thing is to keep the USB plug isolated from the chassis, but unfortunately it doesn’t stop there as Paul discovered.

A dual usb socket with plastic body

If you do use a plastic bodied USB socket, you still have the problem of isolating the end of the USB cable used to charge your device, with potentially disastrous results if the end touches part of the chassis.

Most descriptions of fitting a USB socket go into great lengths about insulating the USB socket from the chassis because of the differences in earthing, but none have included the potential problem with the USB cable itself.

Read Paul’s in-depth description of the problem and his solution to it in his article.