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Tim Murphy
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From the article "Automotive Electrical Fuses -- British Vs American "

"British and American standards for rating electrical fuses are different. Both provide an "Amp Rating" for very similar looking fuses, but the two ratings mean very different things. ! As an example, the 35 Amp fuse called out for many 1950’s/ 60’s/ 70’s vintage Britcars (Lotus Elan & Europa for sure) is roughly equivalent to a US-spec BUSS AGC 17 Amp fuse. Install a US 35 Amp fuse into your LBC fuse box and the wiring harness will melt down before the fuse blows."


Yesterday driving back from the grocery store about a half mile from my house smoke started pouring out of my center consul by the radio.  Upon inspection  I determined that the wire for the cigar lighter (as its labled on the wiring diagram) had shorted out to the body.  Starting at the fuse box until its end in the consul the purple wire for the circuit had completely melted its insulation and burned through the blue tape used to wrap the wire harness.  What other damage it caused I was too mad  to investigate.

And yes, I did have an American buss 35 amp fuse in the fuse block. Damm.

noomg
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Tim,

I would be interested to know what you found after you cooled off and how you resolved the problem. Pretty much the same thing happened to me. I installed a new battery and when I connected it I got smoke from behind the console. The wiring harness behind radio was melted. The wiring to the cigar lighter was totally fried which looks to be point of origin.

Tim Murphy
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AFAIK, it only melted the wire to the cigar lighter. It hasn't affected any of the other electrical circuits that I know of. So I just disconnected the cigar lighter wire at the fuse box and haven't replaced any wiring harnesses or single wires. Take care.

Tim Murphy
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35 amp fuses are specified in the Owners Handbook on page 28. Really negligent of the Jensen company not to correct that for the American market. In any case, that is why a 35 amp fuse will mistakenly get installed.

noomg
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Tim,

I'd say you're exactly right about the fuses. While doing a damage assessment of the wiring harness I noted that the #3 fuse had blown, I was surprised at the amount of damage since the fuse blew. After reading your post I realized what happened. At some time in the past the original #3 fuse had been replaced with a AGC 30 amp fuse, things must have gotten awfully hot before that fuse finally blew.

When I finally get things sorted out I'll replace all fuses with 15 amp fuses.

Esprit2
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The British/ Lucas fuses are rated for the current that will cause them to blow immediately.
The USA / BUSS fuses are rated for the current they can carry continuously.
There's approximately a 2:1 ratio between them.

A UK/ Lucas 35 amp fuse is roughly equivalent to a 17 amp USA / Buss fuse.
A USA / Buss 30 amp fuse is roughly a 60 amp UK/ Lucas fuse.
A USA / Buss 35 amp fuse is about a UK M6 bolt... ;-)

British . . . . ~ American
Lucas . . . . . . BUSS (AGC)
50 amp . . . ~ 25 amp
35 amp . . . ~ 17 amp
30 amp . . . ~ 15 amp
25 amp . . . ~ 12 amp
20 amp . . . ~ 10 amp
15 amp . . . ~ 8 amp
10 amp . . . ~ 5 amp
5 amp . . . . ~ _____
2 amp . . . . ~ 1 amp

Regards,
Tim Engel

Esprit2
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Tim Murphy wrote:
35 amp fuses are specified in the Owners Handbook on page 28. Really negligent of the Jensen company not to correct that for the American market. In any case, that is why a 35 amp fuse will mistakenly get installed.It wasn't just Jensen. All the Britcar manufacturers used British Standards in their manuals.

Regards,
Tim Engel



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