Topic

Hi All - Quick opinion. If you are working on the electrics of your car (MG) say the airbags, Do you disconnect the negative (earth) only, or also the positive? So bot terminals disconnected.

Hi, I have a device which allows disconnection of the earth lead by unscrewing a wheel which then isolates the battery, this I find suitable for nearly all jobs. I can completely remove the wheel to be doubly safe. Note, I also remove the parallel fuse link, which is normally left in circuit, so I can unscrew the wheel when parking anywhere "risky" so that if anyone tries to start the car, it blows the fuse. I think the unit is marketed as a "discarnector".

I rarely feel it necessary to remove both battery connections, but it is important to ensure any loose connector can't fall back and touch the battery. The device I have avoids this possibility.

It's normal practice to remove the negative terminal first.......the reason for this is: If you were to remove the positive terminal first, you run the risk of shorting the system if you accidentally touch a grounded part of the car with the tool you're using to undo the positive terminal.
The opposite applies the re-connection of battery terminals, the positive terminal should be connected first, then the negative......for the same reasons as above.