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MG Midget and Sprite Technical - Fuse on IOW Frog

Car: IOW Frog with 1275 engine, 45 amp alternator, 100/90w headlights and inherited very non-standard, messy wiring.

Hi,
I'm just replacing the solenoid and am upgrading some of the wiring from the alternator, and thought that a large fuse in the thick brown wire from the solenoid to the loom/fuse boxes would be a sensible upgrade. Has anyone done this and what size fuse would be sensible at this point?

regards,
Nick

J.N. Williams

Hello Nick.
I take it the brown wire you're talking about is the supply wire to the fuse boxes. (I don't have a Frog wiring diagram handy).

For what it's worth I suggest it might be a better investment to install fuses for individual loads i.e. Lights, elec fan if you have one and whatever else you have that isn't fused. If you have the patience it's worth fusing the Left and Right Hi and Lo beams individually so that if you lose one you don't necessarily lose the rest. Also by the way it's definitely worthwhile fitting relays for the headlights. I have one for Hi beam and another for Lo. This means the current passing through the dipswitch is minimal - without the relays the entire lighting current is carried by the little spring contacts in the dipswitch and with your uprated lights the dipswitch will appreciate the easier life.

I'd suggest it's better to fuse the loads individually rather than using a fuse in the wire you mentioned because if - say - a light supply shorts to earth and takes out the fuse in that wire you lose a lot more than just a light and, as importantly, you don't know where the problem is. If a fuse specific to a particular function fails you have a pretty good inkling where to look for the trouble.

Hope this all makes sense and helps you. Good luck!

Cheers.

RS Hughes

This thread was discussed between 18/03/2015 and 19/03/2015

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