35A fuse source?

Does anyone know a source of 35A glass fuses in the UK in the correct length?
I can find any number of 30mm long ones, but these don’t fit the XK fusebox properly. I’d guess the originals should be 1" long. There are plenty of idiots selling fuses labelled as 1"/30mm - I suppose 17% inaccuracy is acceptable… Even the classic Jaguar parts suppliers will happily sell you a fuse that doesn’t fit your fusebox.

The closest I can find is Vehicle Wiring Products’ offering of 25mm fuses in 15, 20 or 30A continuous rating. They don’t give the blow rating, but as the originals should be 17.5A continuous or 35 blow, I’m inclined to try the 15A continuous. There shouldn’t really be more than 15A continuous anywhere in the standard lighting etc. circuits, I’d have thought, especially as the lights, horn and cooling fan are all on modern relays with built-in 30A blade fuses.

Did you try looking at SNG Barratt jaguar Parts - they list the Jaguar part number C39572 as the fuse for your XK140 - hope this helps - Tex.

Some good Lucas fuse info here. … Where to get the correct glass fuses - The 'E' Type Forum and thanks to Bob Lucas fuse (ratings) in XK 140 | Jaguar XK 140 FHC Part & Assembly Information also check out bike fuses 25mm


I found quite a number of original (“torpedo” shaped with the correct length) Lucas 35 Amp fuses on eBay UK in the past.

Sometimes even still in a box of 5 (Fifties) or in a paper bag (Sixties).

Might take a few weeks.

Bob K.

Thanks for the tips, all. I’ll have a trawl of ebay to see what I can find. I have boxes of old ones here that I need to sort through.
Barratt’s only have 30mm fuses unfortunately. The suppliers tend not to give dimensions, just the fuse rating, which is not helpful. I don’t know why the sizes have changed, but a 30mm fuse will not fit correctly in a SF4 fusebox. I’m using the original fusebox with cadmium plated steel screw terminals, not brass as the repro ones have. The fuses in an SF4 sit between the screwed terminals, at a slight angle as one spring clip is taller than the other. The 30mm fuses do not engage properly in the flared sides of the spring clip as the screw terminal is in the way. A 1" fuse (25mm) fits very neatly and is held firmly in place. The SF6 fusebox, with just the two fuses for the ignition circuits, has the screwed terminals alongside the fuse holders so there is no problem. I’m sure I’ll be able to locate some correct ones, but if not I have rebuilt fuses before with the correct fusewire soldered to the end caps, so as long as I can get some apart without the glass breaking that is always an option. I’ll report back on the Vehicle Wiring Products ones when they are delivered.

I’ve often wondered if that could be done. I have a few old dead Lucas fuses.
Where do you get the right wire?

I have a small supply inherited from my Dad, who built his own receivers and other devices having spent WWII in the Radio Security Service working with Bletchley Park. But it’s easy enough to get over here from electronics suppliers - a quick look online should throw up several options. I’d assume the same in the US.
The tricky bit was always getting the end caps off the glass tube without breaking it. Sometimes they’re quite loose, other times brittle.

25mm fuses here also sesrch Durite…they do 25mm as do Bike shops/suppliers https://www.vehiclewiringproducts.co.uk/p-673-glass-cartridge-fuse-25mm

have you tried here.

To make your own fuses, look for the product called, appropriately enough, “fuse wire.” Of course a typical spool of that stuff will supply 50 lifetimes of fuses even for a Lucas-equipped electrical system. slight_smile:

The term “multi-ampere fuse wire” can come up with some combo packs that don’t have as vast a quantity of wire, so might be a good hobbyist choice.


Yep, thanks Steve - see post #1!

Robert, I did look at the GSP company, I have an account for plugs etc. with them as they’re very good. As with Vehicle Wiring Products, the only 25mm of higher rating is listed as ‘30A blow’, which isn’t very precise - I presume that means 15A continuous, not sure. Every seller now seems to only have 35A in 30mm which is too long. I don’t imagine 5A here or there makes much difference so the 30A are on order.

Wow, even Amazon has fuse wire.

I’m interested in your description of ‘torpedo’ shaped fuses - do you mean the ceramic type with the pointed ends? Maybe that’s a 120 thing - the 140 fusebox (SF4 and SF6, although the SF6 has open ends so is perhaps not affected) has to have flat ended fuses to fit between the terminals, hence the issue with the modern replacements. I know nothing about 120s - maybe the fusebox is different.

Voltage regulator fuse box from my '38 SS saloon with Lucas pointed end fuses.

I presume this is what is meant by torpedo shaped.

I believe in some fuse boxes they would fit in a pair of terminals with holes, like a festoon light bulb.

Yes, completely different from the 140 of the fifties. I don’t think I’ve ever seen fuses like those in a UK car - my '37 Riley has that type of fusebox but I haven’t got around to looking inside it yet! Too busy making new wings and new seat pans.
A ceramic version of those ‘canoe’ shape fuses is still pretty common, but no glass tubes.


Somewhere in the Fifties was the changeover from the “conical” to the “straight end” type of fuses, so you may encounter both in our Jaguars. Note that Lucas still showed the “conical” end type in their 400E catalogue of 1960, but I guess the change-over was earlier than that…

The Control Box of the XK 120 was Lucas RF.95/2 which had two fuses “on board”. This was fuse Lucas 188218 which formally is a 1¼" long “Conical or Cartridge” type of fuse (see above chart). There is space for this longer fuse in the RF95/2 Box (but the 1" long fuse fits as well).

The Fuse Box of the XK 120 was Lucas SF-4 and Jaguar refers to the same fuse Lucas 188218 to be used here as well . But in fact the SF-4 is “on the edge” with regard to the available space for the longer “torpedo” fuse type and in fact the 1" long type fits better. The picture below shows my SF-4 with the longer fuses and it’s a tight fit.

Note that the XK 140 SPC still refers to the same Lucas fuse numbers like 188218 for the 35A version, meaning theoretically this could still be the longer “conical” version.

So apparently Lucas did change to the 1" long version with straight ends at a certain moment, but I couldn’t find a “formal introduction date”. We also note that Lucas didn’t change the code numbers for the fuses and there never were “supersession” numbers for these fuses published.

Bob K.

From the SS left headlight dipping mechanism.

There was even a spare fuse holder.

There are five holes for spare fuses in my regulator above over on the left.

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There is another issue to consider as well. The Ampere rating of the 50s and 60s is not the same as the measurement of today.
There was an article about this in the XK Gazette some 5-10 yrs ago. I copied the article but can’t find it now.
The old 50amp is equivalent to about 30 now if I remember correctly.
Perhaps there is info on this on this forum…

Hmm, that’s interesting Bob. Here’s a photo of my original SF4 with a 30mm modern fuse in place.

It doesn’t quite fit between the connector blocks, and is not properly engaged in the spring clips at the higher end. If the ends were pointed it wouldn’t fit at all. I suspect the part number is purely a rolling reference number rather than a specific part.
The fuse ratings were always two numbers - a value for continuous current and a ‘blow’ value. Usually the blow was around double the continuous.

edit - oops, I hadn’t realized how dusty it has got…

Hi Peder…i posted this info in a link above… 50amp is always 50amp…however fuse ratings differ asin this chart
So the basic Lucas info:-
Lucas 50 amp - continuous 25 amp
Lucas 35 amp - continuous 17 amp
Lucas 25 amp - continuous 12 amp
Lucas 20 amp - continuous 10 amp
Lucas 15 amp - continuous 8 amp
Lucas 10 amp - continuous 5 amp
Lucas 2 amp - continuous 1 amp