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MG TD TF 1500 - Fuses for TF

Hi All,

My 1954 TF does not have any fuses in the fuse holder. I cannot tell where the 35 amp fuse and 50 amp fuse go. Also, I understand there is a difference between the British glass fuses and the glass fuses produced here in the U.S. Can anyone enlighten me please? Thanks, George
GH Higginson

George there is absolutely a difference. UK fuses are rated for blow and American ones are rated for circuit. So, a 35 amp UK fuse blows at 35 amps, whereas a 35 amp US fuse will blow at about 55 amps (before which your harness will likely start smoking!).

Either use Lucas fuses (preferable) which you can get from most of our usual suppliers, or use a conversion table to choose a reasonable substitute American fuses.

Here's a good article on the subject:

http://www.drooartz.com/index.php?page=29
Kevin McLemore

There are some misconceptions about British fuses. Originally they had a double specification on them - i.e. 17amp/35 amp The fuse will hold forever at 17 amps and blow instantaneously at 35 amps. This is basically the same for American fuses, except for slightly different ratings - American fuses have a single rating for a standard fuse 15 amps will hold forever at 15 amps and blow instantaneously at 30 amps. Our fuses have a single rating ie 15 amps. All of these ratings are the standard both for British and American. American also have a slow blow fuse, totally different from the above. I have looked at the ratings for the slow blow fuses many years ago, but don't remember how those are rated - they are used in applications where there are large, short duration spikes of high current. For the MGs, either a 17/35 amp (or more recent rating of 35 amps) British rated fuse or an American 15 amp fuse. Cheers - Dave
DW DuBois

Hmm... that's strange, Dave. Bussman (fuse mfg) converts a 15 amp US fuse to a 25 amp British fuse. Not to disagree, but out of curiosity, how did you calculate differently?
Kevin McLemore

See below.

DW DuBois

The fuse rating is kind of a soft number. The current needed to blow a fuse is not a single value; it's a function of time and overcurrent. For more info on this than you probably want, see http://www.nonlintec.com/sprite/electrical/.
S Maas

I ordered the fuses from Moss to be on the safe side. The only thing I do not know is which fuse goes in which slot. The manuals show 2 fuses, but do not say which goes where. Does the 50 amp go in A1 - A2 or A3 - A4?
Of course the 35 amp goes in the other slot. Thanks again for all of the help. George
GH Higginson

If I remember correctly, the 50 amp goes in the slot for the horns. Cheers - Dave
DW DuBois

Forgot to add the 50 amp fuse goes in the slot that has a single brown wire at one end and 2 brown/green wires on the other end. Cheers - Dave
DW DuBois

This thread was discussed between 22/06/2015 and 24/06/2015

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