Installing an Auxiliary Fuse Block

by John Trifari

Originally published in the Austin-Healey Magazine, February 1995

The Healey electrical system leaves much to be desired, starting with a limited number of fuses. Tapping off these fuses for a clock and a voltmeter stressed the ability of the screw terminals to handle any additional wires, so when I chose to add a few more accessories, I had to re-evaluate my fuse requirements and just how I was going to best protect the car’s electrical system.

My first thought was an ambitious one. I actually contemplated pulling the fuse bloc, replacing it with a bloc with more fuses and rewiring things. After taking a reality break and contemplating the limited space around the bloc, I decided that this would not be a smart idea, at least until the Healey’s engine comes out for rebuilding, so I settled on an auxiliary fuse bloc instead.

The 4-circuit fuse bloc described here is from JC Whitney (part #13VY6O4ON) and lists for $5.49.It will handle up to 30 amps per circuit and uses conventional fuses. Blocs with more circuits are available. The 4-circuit bloc is mounted vertically on the small panel below the ID plate on the passenger side of the engine compartment, where it is easily accessible. The panel is used to blank off the hole for the steering column of a right-hand-drive car, and can be easily removed in order to mount the fuse bloc.

As shown in Figure 1, I interconnected the fuses on one side using short loops of wire with ring connectors soldered to each end. Power to the fuse bloc itself comes from regulator terminal A1 via a short length of wire with an in-line fuse. Connecting the power-in line at this point allows circuit loading to register on my ammeter. At the moment I am using only three of the four fuse terminals: One powers an under-dash map light; the second runs the windings of a relay I use as a switch for the fog laps I've installed. (Power for the relay contacts comes off the low-beam side of the dip switch so that the fog lamps go off when the high beams go on. The third fuse powers a standard 12-volt cigarette lighter socket I've mounted on the side wall on the driver's side. I use this for a trouble light and to power my cellular phone. My CB and radio run off the switched side of the ignition, and cannot be inadvertently left on. All accessories running off the supplemental fuse bloc by-pass the ignition, however, so remember to turn off anything connected through those fuses, and to be careful working around that area — those fuses are hot.

Figure 1: Fuse bloc is screwed onto panel used to blank off right-hand drive steering column. Fuses are interconnected by short loops of wire with ring connectors, and to nearby regulator terminal A1. In-line fuse protects regulator. Only three of the four circuits are in use.

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