I posted the following on the same subject to the MG list:
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I am all for adding relays to our car. I have had extensive electrical
upgrading on my Healey and am waiting my next at the shop to get the same
things done for the BGT. Turning on the ignition activates a 75A relay
which switches power directly from the battery terminal on the solenoid to
an eight position fuse block.
You only need one relay for both high and low beams. Most relays have two
sets of contacts. One normally closed, and one normally open. The low beams
go through the normally closed contacts. When you want the high beams you
activate the relay and the normally open contacts close and the normally
closed contacts open. That way the most used low beams are activated
passively and the relay is only used for high beams.. In the unlikely event
of a relay failure, you always have the low beams.
BTW, The 75A realy is fused, and the light relay is activated by the light
switch with the current for the headlights coming directly from the battery
through a fuse on the block. The block uses blade fuses.
The block and relays came for www.ties4less.com. No interest other than a
satisfied customer.
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As for fusing, modern cars use a fusible link that opens when there is a
short. I prefer a circuit breaker which fits into the fuse block, just as a
bladed fuse does.
Jack
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