35A Fuses

[af3683]

Hello,

I bought some 35A fuses from Moss which they claimed over the phone are 17.5A continuous, although the fuse only says "35A". When I compared the size of the Moss fuses to a Lucas 35A fuse in my car, the Moss fuse was actually larger than the Lucas fuse. I understand from reading posts on this forum that American fuses are a bit larger than the British standard fuses. This makes me think that the Moss fuses may actually be American fuses and not British standard fuses which are 35A continuous at 17.5A. Does anyone have any thoughts about this? Thank you.

Art

 

[Andrew Mace]

Art, it's definitely worth investigating further! It's been decades since I've actually had to buy a "proper Lucas 35 amp / 17 amp continuous" fuse*, so I don't know what's sold as such nowadays. I'd almost be tempted to find a way to put a variable load on one and see where it blows! :wink: (But I'd do that with test equipment, NOT with your car's wiring harness!)

*Between my own parts cars and junk yard scrounging over the years, I've managed to collect more than a few good spare fuses!

 

[Member 10617]

Art:

I spoke with people at Moss during the summer about this.

Moss fuses are 35 amps and 17.5 continuous ("hold"). Moss goes by the Lucas method, which means that a Moss 35 amp fuse will blow at 35 amps. A fuse that uses the USA method and is rated at 35 amps is continuous at 35, so it will not blow until it is over that, which means it will do damage to your car.


The message I have gotten from many sources: do not use a USA rated 35 amp fuse in your British car.

The fuses I received from Moss are almost the same size as the original Lucas fuses, but not torpedo shaped but squared of at the ends. they work fine in my 58TR3.

 

[TR3driver]

Are there any other markings on the fuses from Moss? Can you measure length and diameter?

There are reproduction Lucas fuses available, that are marked only with the "blow" current. But it's also possible that there was a mixup at Moss. American fuses will almost always have the fuse code (AGC, SFE, MDL, etc) marked as well as the current rating.

 

[Geo Hahn]

Used to be (recently in fact) that the Lucas fuses from the big suppliers were real Lucas and the conductor was wire secured with a dab of solder at the end of each cap.

The most recent ones I got from TRF look more like plain Jane Buss fuses with the blade type conductor. My, but I'm fussy... but then those fuses sit in plain sight in a TR3.

There are American 14 amp fuses that look more the correct length (shorter) and they can be opened and a vintage Lucas label added by the truly anal (moi).

 

[TR3driver]

The fuses I received from Moss are almost the same size as the original Lucas fuses, but not torpedo shaped

Just for clarity, the original fuses were not torpedo shaped either. The torpedo shaped ones were Bosch, not Lucas.

 

[af3683]

Randall-

The only markings on the Moss fuses are "35A" which appears on the ends of both caps. They measure 1/4" in diameter and 1 1/4" long. If the Moss fuses are supposed to be reproductions of the Lucas fuses, I would think that they would be similar in size. The Moss fuses are probably a 1/4" longer than one of the Lucas 35A fuses in my car. I'm not convenienced that they are 35A and 17.5A continuous hold.

Art

 

[Geo Hahn]

Those sound about like what I got from TRF... perhaps this is the 'new' Lucas fuse. TRF never claimed they were a reproduction of anything just that they were the correct (British system) 35a fuse. Perhaps we're expecting a particular appearance when they are selling function.

Some of my old Lucas fuses do have round ends -- could that be what was meant by 'torpedo shaped'? They are the usual glass fuses (marked Lucas) not a ceramic like some Bosch.

 

[Member 10617]

Hi, Randall,

I am a bit confused (no pun intended). You say that the torpedo fuse was Bosch and not Lucas, but here is what is on my car (the little paper in the fuse, if it is too small to read here, says "35 Lucas"):

 

[Member 10617]

Here is a better photo of the fuses in question. On top is an original Lucas 35 amp fuse from my 58TR3, and on bottom is a 35amp fuse from Moss purchased a few months ago. You see the differences, but they seem to be the same size.

 

[TR3driver]

Well, live and learn as they say. I have a modest collection of original Lucas fuses and they all have conical ends (like your reproduction) except for the blob of solder. The Bosch-type fuse I was talking about can be seen here:
https://en.wikipedia.org/wiki/Fuse_%28automotive%29#Bosch_type
although I have also seen replacement Bosch fuses with a glass tube and the element inside the tube.

And the original Lucas fuses I have are only about 1-1/8" long, rather than 1-1/4".

Sorry for the negative clarity.

 

[af3683]

The 35A fuses that I got from Moss a few days ago have 35A printed on the ends of both caps. Those are the only markings. There is no paper insert. Clearly, Moss is now selling different 35A fuses and who knows if they are the 17 1/2 continuous hold slow blow type!

Art

 

[TR3driver]

Well, Moss is clearly aware of the distinction; and these clearly aren't ordinary American fuses. I'd say the odds are pretty good that they are suitable replacements for the originals.

But for verification, I'd suggest taking one and loading it to 20 or 25 amps for a few minutes. If it blows, it was the proper rating. If not, it's too high.

The other alternative of course is to just pick up some AGC-20 or SFE-20 fuses and use them. They might cost you a point at concours, but there is no question about what you've got, and they are readily available practically anywhere in the US.

 

[Geo Hahn]

...But for verification, I'd suggest taking one and loading it to 20 or 25 amps for a few minutes. If it blows, it was the proper rating...

Cool. I think I'll test all mine that way. :wink:

 

[ianrand]

Interesting topic. May I ask if any of the old timers can remember the approx year Lucas glass/paper fuses changed over from the soldered tip end to the formed cap end? For example: 1960 car had soldered tip fuses from the factory and as the OEM parts inventory was depleted 1961/62 cars started having formed end fuses from the factory.) Thanks! ianrand