Welcome to our Site for MG, Triumph and Austin-Healey Car Information.


TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR6 - Fuse Amp

For some reason, I can't seem to find on the schematics fuse amp ratings. So here's a few questions:
1)From top to bottom positions in the fuse box, what are the original amp ratings of each fuse on a 1970/71 model.
2)I noticed that each model year, the schematics show slight changes in the electrical circuits. Does the fuse amp ratings change from year to year? If so, what are the original fuse amps for those specific years?
3) When I add a new fuse box for additional circuits, how do I figure out:
A) The correct fuse amp to use.
B) What gauge of wire to use for long and short runs

Hi Benji

According to Dan Master's book, the fuses he recommends are 10A for the red fuse, 15A for the Purple and 20A for the green. Those are the American ratings, which are different from the English fuse ratings.

To the best of my knowledge, the fuses which came standard are all 35A English (which means roughly a 17.5A continuous load or 35A short duration peak). I hope that's what they are, because that's what I have - and I have a load of spares to allow for my rather simplistic approach to electrical troubleshooting... The only place I know stocks the standard original style fuses is TRF - just be aware that they have a 12 pack of fuses which is a lot cheaper than buying the fuses individually (add "/12" to the end of the fuse part number).

New fuses (and wiring) should be rated for a bit more than the maximum load you plan to use - the wire ratings are below (from Dan Master's book):

18 gauge - 5A
16 gauge - 10A
14 gauge - 15A
12 gauge - 25A
10 gauge - 50A
8 gauge - 80A

The fuse has to be rated for the smallest wire rating, so if your 10 gauge wire feeds to three 18 gauge wires you still need a 5A fuse, or so I understand.

Can you tell I have been reading Dan Master's book recently? I highly recommend it before you get into any wiring...

Hope that is some use
A Hewitt

Is your reference to wire guage for American guage wire or British? They're different you know.
Doug Baker


Those are American - I don't know where you would get British sizes over here (measured in strands, right?), and I figured that if you know enough to find British wire sizes in America, then you know what load they can take! If, on the other hand, you get your wire from Home Depot, Pep Boys, WalMart or wherever (as I did) you will be looking at the gauge sizes I listed. For the sake of completeness, here are the ratings for British sizes...

9 strands - 5.75 amps
14 strands - 8.00 amps
28 strands - 17.50 amps
44 strands - 25.50 amps
65 strands - 35.00 amps
84 strands - 42.00 amps
120 strands - 60.00 amps

Thanks again are due to Dan Masters, of course.

A Hewitt


I have a couple of fuse and wire sizing charts in PDF files. I'll send them to you.

HP Henry Patterson


You should have the charts. If not let me know.

One of the charts shows the wire gauge you should use for a given run length. That should help you with part B of your question.

HP Henry Patterson

Henry and Alistair,
Thanks for those charts. That's info that I'll archive with the schematics.
Henry, Can you clarify how to read the wire sizing table?


If you're referring to the tables from the PDF file from RBE electronics then the most useful table for most of us is at the bottom of the page. It show's the proper wire gauge for a particular run in feet as long as you know what amperage the wire will carry. At the very bottom of the page there is an example on how to use the table.

As far as the other file, it may not be much use to most of us as it's suited more towards engneering. For example it has a fuse derating chart which shows how a fuse amperage rating will be actally lower when at 100 deg.C. Some of the other stuff may be usefull though. But again the best table is the one at the bottom of the RBE page.

Hope that helps. If not, send me an email.

HP Henry Patterson

This thread was discussed between 07/05/2008 and 20/05/2008

Triumph TR6 index

This thread is from the archives. Join the live Triumph TR6 BBS now