Here's a similar thread on the classic Mini forum.
http://www.theminiforum.co.uk/forums/topic/223427-glass-to-blade-fuses/

Their experts raise the same points:
• Never simply replace a blown fuse, but establish and rectify what caused it to blow;
• Be aware of the difference between today's fuse rating standards, where they're marked with their "continuous Amps" rating, and older British car fuses, which are marked with their instant "blow" ratings;
• NEVER go down the trial-and-error route of fitting a fuse that's rated to instantly blow close to the continuous Amperage! At the end of the Mini thread, there's a very good explanation of why this seemingly sensible practice is actually dangerous. It's all about how another feature of fuses -- something called the "slow blow" characteristics, which give the impression everything is good over many months, while under the fuse box cover or dashboard, things are heating up ;
• If you're thinking of (or already have) modified your Landy's fuses to blade type fuses, speak with your Insurers, as this constitutes a major "modification" and, unless done by a qualified auto electrician, will almost certainly invalidate your Insurance;
• Get yourself a fire extinguisher .

As an aside, I'm currently fitting a flashing beacon to my Ninety, as it is also used as a "recovery vehicle". The beacon draws around 5A. So what gauge wire should I use: one rated at 5A, maybe? Or, after reading about continuous and blow Amperage in fuses, you might think 10A or 16A wire? Well, don't forget that all wire has a resistance that doesn't just relate to the cross-section of the core, we must also consider the length of the wire. Hmm, this stuff quickly gets complicated. My cable run will be about 3.5 meters, so the answer is that I'm going to ask ask a qualified auto electrician. Better safe than sorry. Fire extinguishers are expensive!

Rick
 
Richard Seddon said:
Here's a question: WHY would anyone go to the tremendous trouble and cost of replacing the factory-fitted main fuse box, just so they can use spade fuses in place of traditional glass fuses?

Would I be correct in thinking that people are getting a lot of blown fuses? And that the faffing about involved in sending away for older-type one inch glass fuses, plus the relative ease with which inserting spade fuses makes all that cost and effort of doing the replacement worthwhile?

If these are your reasons, then you've got far bigger problems than seeking advice of getting and fitting a new fuse box. You MUST investigate why those fuses are blowing! Never, never ever, replace a blown fuse and think "job done"; you may have an intermittent electrical short that could lead to a fire in your 30+ something years old Landy. Indeed, I think I'm correct in saying that electrical fires are relatively common in old Land Rovers.

Ok, I've not had to change a single fuse in my 1987 Ninety for as far back as I can remember. In fact, not since I discovered the difference between "continuous" and "blow" fuse ratings, which led to me fitting the correct Amperage fuses and writing my first post on here.

Not one single blown fuse in many years.

So, how come I rediscovered this thread? Well, it popped up when I saw that a certain company had an "offer" on for 1" glass fuses, and I needed to remind myself (Google) what Amp rating fuses I might want to put into my spare bulbs and fuses box. I could only dimly recall that the ratings were NOT "what it says on the tin" (or fuse box cover), so to speak.

If you don't believe me, try searching Rimmer Bros website for a 35A 1" glass fuse. It says, "Fuse - 35 amp 17 amp Continuous - Glass type ... GFS3035 - Genuine MG Rover". Ok, it might have been more clearly written, but it is important you're aware of this, particularly if you're looking at blade vs glass fuse ratings. Fitting too small an Amperage fuse -- one that is designed to "blow" at an Amperage close to your "continuous" Amps -- this will cause that blade fuse to heat up, and while it might not blow for several months, that ain't a good thing. Things might be glowing behind your fuse box cover.

Apparently it all goes back to how the UK motor industry rated fuses, versus other countries, back in the day. In modern (international market) cars you fit the Amps rating it says on the fuse box, which is the continuous Amps rating. That's because the actual fuses are marked with their continuous Amps rating. Whereas on old Lucas/BMC vehicles, the manufacturer also tells you the continuous Amps rating, but the fuses themselves are marked with their so-called "instant blow" rating. Apples and Oranges, from the days when people were expected to be more knowledgeable. (Before the days of "dumbing down".) Put simply, they've changed the standards.

Remember, the purpose of any fuse is to "protect the wiring". So you must fit a fuse that is capable of handling the continuous Amps, but will melt before the wires do -- the so-called instant blow rating. And that gives us a problem, because you can't simply replace a 35A glass fuse with its equivalent 35A blade fuse. As I've said, the glass 35A fuse is designed to carry only 17A continuously, whereas the blade fuse is designed to carry 35A continuously, and I've no idea at what Amps it will actually blow, other than that your wiring is likely to start smoking before the fuse blows.

Consequently, not only do I question why you'd swap out the manufacturer's perfectly good original equipment glass fuse box, but also why you're entertaining all this cost and work, instead of diagnosing what's called "the problem behind the problem"?

Finally, don't forget that fitting a different fuse box is what your insurance company calls a "modification". If your beloved Landy has the misfortune of going up in smoke, then your insurance assessor will probably go straight to your shiny new fuse box. S/he'll ask whether it was fitted (or certified) by a qualified auto electrician and, as you probably didn't notify the "modification" to your insurers, you're unlikely to get a pay out.

Disclaimer: this post is based upon my personal understanding, but I am not a qualified auto electrician, therefore, it is for discussion purposes only, and you are responsible for undertaking your own research by consulting a qualified auto electrician who is familiar with classic car fuses. No responsibility is accepted for errors or omissions. The purpose of this post is to raise your awareness of the difference between "continuous" and "instant blow" Amps in automotive fuses, so you can have a sensible conversation with your classic car fuse supplier.

Good-luck,
Rick
Click to expand...

I agree with some of what you have wrote there, certainly about the different ratings of fuses, that’s without mentioning fuse speed.

I do have a few “issues” with some bits though. Auto electrics don’t need “certification”, but if you think they do, can you link to the regs/governing body?

There is a huge advantage to replacing glass fuses with blades, ease of replacement. Most places sell blade fuses, and these are easy to get hold of. Glass fuses are less common and harder to get hold of. I agree with you about wiring and fuse ratings not being directly “linked”. I have seen some posts on here and though “don’t do that, it’s a fire waiting to happen”. That is where a basic understanding of what an individual is doing, is needed for the job to be done safely. A simple google search for any of the wiring suppliers, Altec Automotive, Polevolt, VWP etc, all show “current ratings” for wires, and as such the correct fuse can be selected. After all the fuse is only there to protect the cable.

As for a fuse box change being a modification, is it really? Is a galvanised chassis a “modification”? I know some insurers don’t see them as such, but each to their own.
 
Richard Seddon said:
Here's a similar thread on the classic Mini forum.
http://www.theminiforum.co.uk/forums/topic/223427-glass-to-blade-fuses/

Their experts raise the same points:
• Never simply replace a blown fuse, but establish and rectify what caused it to blow;
• Be aware of the difference between today's fuse rating standards, where they're marked with their "continuous Amps" rating, and older British car fuses, which are marked with their instant "blow" ratings;
• NEVER go down the trial-and-error route of fitting a fuse that's rated to instantly blow close to the continuous Amperage! At the end of the Mini thread, there's a very good explanation of why this seemingly sensible practice is actually dangerous;
• If you're thinking of (or already have) modified your Landy's fuses to blade type fuses, speak with your Insurers, as this constitutes a major "modification" and, unless done by a qualified auto electrician, will almost certainly invalidate your Insurance;
• Get yourself a fire extinguisher .

As an aside, I'm currently fitting a flashing beacon to my Ninety, as it is also used as a "recovery vehicle". The beacon draws around 5A. So what gauge wire should I use: one rated at 5A, maybe? Or, after reading about continuous and blow Amperage in fuses, you might think 10A or 16A wire? Well, don't forget that all wire has a resistance that doesn't just relate to the cross-section of the core, we must also consider the length of the wire. Hmm, this stuff quickly gets complicated. My cable run will be about 3.5 meters, so the answer is that I'm going to ask ask a qualified auto electrician. Better safe than sorry. Fire extinguishers are expensive!

Rick
Click to expand...

Now your making a mountain out of a molehill. If you have something that draws 5A, you should add something called “diversity factor”, basically you would add 10%. So now you have 5.5A, over a 3.5Mtr run, at 14V, this will equate to less than mAs (if you don’t understand what I’m talking about, then best not to do anything more). So now you can add a few more mA and your up to 5.6A. So get a cable that is rated to over 7.5A, remembering that the fuse protects the cable and not what it’s connected to, and connect the beacon to the 7.5A fuse.
 
mick 1986 said:
I agree with some of what you have wrote there, certainly about the different ratings of fuses, that’s without mentioning fuse speed.

I do have a few “issues” with some bits though. Auto electrics don’t need “certification”, but if you think they do, can you link to the regs/governing body?

There is a huge advantage to replacing glass fuses with blades, ease of replacement. Most places sell blade fuses, and these are easy to get hold of. Glass fuses are less common and harder to get hold of. I agree with you about wiring and fuse ratings not being directly “linked”. I have seen some posts on here and though “don’t do that, it’s a fire waiting to happen”. That is where a basic understanding of what an individual is doing, is needed for the job to be done safely. A simple google search for any of the wiring suppliers, Altec Automotive, Polevolt, VWP etc, all show “current ratings” for wires, and as such the correct fuse can be selected. After all the fuse is only there to protect the cable.

As for a fuse box change being a modification, is it really? Is a galvanised chassis a “modification”? I know some insurers don’t see them as such, but each to their own.
Click to expand...

Mostly agreed, Mick,
But the crucial question is, why do you care about "ease of replacement" and whether "blade fuses ... are easy to get hold of"? Surely replacement of a blown fuse should be such an infrequent occurrence that any inconvenience is as nothing compared with major rewiring.

As for what Insurance companies classify as a notifiable "modification". Things such as changing the vehicle's colour; applying vehicle graphics; fitting a different size staring wheel; upgrading to a later design of engine; changing your wheel diameter; ... Indeed, quite literally, any modification you make to your Landy from how it originally left the factory is a notifiable "modification" for insurance purposes. Surprisingly, this includes fitting of genuine Land Rover options which might well have been fitted from new: e.g. side steps or safety improvements. The rule is "if it wasn't on the vehicle the day it left the factory, then it's a modification that must be notified". Believe you me, my dad was in motor vehicle repair for 50 years. If an insurance company can worm their way out of paying out, they will.

Regarding "certification" of auto electricians, perhaps I should have said "qualified". They must have a City & Guilds or HND or something? Although, in the Netherlands, they'd definitely have to be Certified in order to operate legally.

All the best,
Rick
 
mick 1986 said:
Now your making a mountain out of a molehill. If you have something that draws 5A, you should add something called “diversity factor”, basically you would add 10%. So now you have 5.5A, over a 3.5Mtr run, at 14V, this will equate to less than mAs (if you don’t understand what I’m talking about, then best not to do anything more). So now you can add a few more mA and your up to 5.6A. So get a cable that is rated to over 7.5A, remembering that the fuse protects the cable and not what it’s connected to, and connect the beacon to the 7.5A fuse.
Click to expand...

No, I'm not "making a mountain out of a mole hill", Mick. I'm simply saying that not everything in electronics is plain and simple. Your average Joe (someone like me) has no idea about "diversity factors" -- is that something to do with cables of colour or male vs female connectors ? YES, "if you don’t understand what I’m talking about, then best not to do anything more" is exactly what I'm saying . I don't, so I'll ask someone who does.

R
 
Richard Seddon said:
Mostly agreed, Mick,
But the crucial question is, why do you care about "ease of replacement" and whether "blade fuses ... are easy to get hold of"? Surely replacement of a blown fuse should be such an infrequent occurrence that any inconvenience is as nothing compared with major rewiring.

As for what Insurance companies classify as a notifiable "modification". Things such as changing the vehicle's colour; applying vehicle graphics; fitting a different size staring wheel; upgrading to a later design of engine; changing your wheel diameter; ... Indeed, quite literally, any modification you make to your Landy from how it originally left the factory is a notifiable "modification" for insurance purposes. Surprisingly, this includes fitting of genuine Land Rover options which might well have been fitted from new: e.g. side steps or safety improvements. The rule is "if it wasn't on the vehicle the day it left the factory, then it's a modification that must be notified". Believe you me, my dad was in motor vehicle repair for 50 years. If an insurance company can worm their way out of paying out, they will.

Regarding "certification" of auto electricians, perhaps I should have said "qualified". They must have a City & Guilds or HND or something? Although, in the Netherlands, they'd definitely have to be Certified in order to operate legally.

All the best,
Rick
Click to expand...

I think you will be surprised at what real qualifications most people in the motor trade have. I know it’s getting better at the minute, but I don’t think everyone has a cert for everything they are doing.

I’m not arguing about what is and isn’t a modification, as ANYTHING that is different from how it left the factory is actually a mod, it’s what YOUR insurance CLASS as a modification. Most decent insurers know these vehicles are heavily modified, and as such don’t really charge extortionate amounts for them.

Things happen and fuses do blow. Yes it should be a very infrequent occurrence, but sometimes people get things wrong and lives touch earths/returns. This will blow the fuse. A fault state could occur and cause a fuse to blow (an internal short in a light as an example).

I’m leaving it at that as I’m flogging a dead horse.
 
Richard Seddon said:
No, I'm not "making a mountain out of a mole hill", Mick. I'm simply saying that not everything in electronics is plain and simple. Your average Joe (someone like me) has no idea about "diversity factors" -- is that something to do with cables of colour or male vs female connectors ? YES, "if you don’t understand what I’m talking about, then best not to do anything more" is exactly what I'm saying . I don't, so I'll ask someone who does.

R
Click to expand...

Nothing in electronics is simple to someone who knows nothing about electrics.

I’m not trying to have a pop at you, but you came to this thread and said that it wasn’t a good idea to go changing a fuse box from glass to blades, quoting fuse reaction times/blowing characteristics, and then on the next page state that “your average joe and don’t know, so you will ask”. Which is it? Do you know what your talking about, or not?
 
No disrespect to the electronics experts on this forum. But here's a great example of the kind of thing that a rookie like me might think is a clever way to save money in wiring in a blade fuse without the expense of purchasing a properly designed fuse holder.

A good idea gone wrong.jpg

[Source: warning from mjlorton on YouTube]

Two female spade connectors were plugged into the male connectors of a spade fuse... Notice that the wiring loom looks fine, it's the fuse that massively overheated. Oops!

I think it nicely exemplifies why vehicle electrics might look simple, yet even the simple stuff can have hidden dangers.

Rick
 
Richard Seddon said:
No disrespect to the electronics experts on this forum. But here's a great example of the kind of thing that a rookie like me might think is a clever way to save money in wiring in a blade fuse without the expense of purchasing a properly designed fuse holder.

View attachment 171625
[Source: warning from mjlorton on YouTube]

Two female spade connectors were plugged into the male connectors of a spade fuse... Notice that the wiring loom looks fine, it's the fuse that massively overheated. Oops!

I think it nicely exemplifies why vehicle electrics might look simple, yet even the simple stuff can have hidden dangers.

Rick
Click to expand...

Low voltage DC is simple, that’s why there are no regulations for it.

Using female spade connectors isn’t the cause of the problem.

The wire may well be fine, if it’s rated to carry the current of the fuse. The copper conductor would need to be inspected very carefully after that.

Take a look at the link I posted about fuse characteristics and see why the fuse melted. It looks like a green 30A fuse, so can run at 33A for over 100 hours, at up to 100deg or so. The plastic was probably of a cheap ****e quality and melted before the design current/heat of the fuse was reached.
 
You'll notice that the heat appears to have been generated where the female spade connectors touch the male connectors of the spade fuse, rather than within the fuse itself. I'd guess that the contact points were making a poor connection -- creating electronic resistance -- but it does nicely illustrate what can go wrong.

Presumably, this is also a warning about the potential risks of buying unverified parts off for fleaBay, rather than a reputable UK supplier? It also suggests that it's a good idea to wire up and test the circuit -- resistance testing with a multimeter -- before fitting inside a vehicle. Any advice on this, Mick?

Yes, the references you sent are very useful. Thank you for digging them out.

What would be really useful would be a table giving the Amps info from the reverse of the 90-110 Fuse box cover, correlated to the Amps ratings printed on the glass and equivalent spade fuses. E.g. if the fuse box says 7.5A, then I believe that the correct glass fuse is marked 15A and the correct spade fuse would be marked 7.5A ? But, although I'm pretty sure on the glass fuses, there may be other factors I'm not aware of for blade fuses. Is this something you could write for us, Mike?

As for reputable specialist UK fuse suppliers, who sell in small quantities. Any suggestions, please? Or is it more of a case of choosing a reputable manufacturer, then looking at who sells them (you did mention manufacturers publish the data on fast blow, slow blow, and continuous current). I guess we laymen could look it up, but you know better what you're looking for.

Any help very much appreciated,
Rick
 
Richard Seddon said:
You'll notice that the heat appears to have been generated where the female spade connectors touch the male connectors of the spade fuse, rather than within the fuse itself. I'd guess that the contact points were making a poor connection -- creating electronic resistance -- but it does nicely illustrate what can go wrong.

Presumably, this is also a warning about the potential risks of buying unverified parts off for fleaBay, rather than a reputable UK supplier? It also suggests that it's a good idea to wire up and test the circuit -- resistance testing with a multimeter -- before fitting inside a vehicle. Any advice on this, Mick?

Yes, the references you sent are very useful. Thank you for digging them out.

What would be really useful would be a table giving the Amps info from the reverse of the 90-110 Fuse box cover, correlated to the Amps ratings printed on the glass and equivalent spade fuses. E.g. if the fuse box says 7.5A, then I believe that the correct glass fuse is marked 15A and the correct spade fuse would be marked 7.5A ? But, although I'm pretty sure on the glass fuses, there may be other factors I'm not aware of for blade fuses. Is this something you could write for us, Mike?

As for reputable specialist UK fuse suppliers, who sell in small quantities. Any suggestions, please? Or is it more of a case of choosing a reputable manufacturer, then looking at who sells them (you did mention manufacturers publish the data on fast blow, slow blow, and continuous current). I guess we laymen could look it up, but you know better what you're looking for.

Any help very much appreciated,
Rick
Click to expand...

The heat buildup could have been from anything really, dirty cable, dirty spade connector, poor crimp, dirty fuse contact, or simply running the fuse right at its peak for a sustained period. I do think the photo, and reasons behind the fault, have a place in the forum, but maybe not in the context I took your posts.

For fuse suppliers, I find RS Components is a reputable supplier. The RS pro brand is good quality and not very expensive.

As for writing up fuse specs, that’s not something I have time to do with my current job and rebuild of my 110. If I find I have more time in the next few months, then I may give it a go and see how it’s taken.

Testing circuits is very good practice, and mandatory for anything to do with AC fixed wiring. The problem comes when the tester doesn’t quite understand the results of the test being performed. This is why electricians get so “tetchy” when “unskilled” people start messing with circuits. I would advise everyone to test a 12V circuit before it’s powered up, but knowing how the circuit works and understanding the test results are what will determine if a circuit is classed as good or not.

I’m happy to help anyone with any electrical/wiring issues on any vehicle, but I don’t know everything about every aspect of electrics.
 
Richard Seddon said:
You'll notice that the heat appears to have been generated where the female spade connectors touch the male connectors of the spade fuse, rather than within the fuse itself. I'd guess that the contact points were making a poor connection -- creating electronic resistance -- but it does nicely illustrate what can go wrong.

Presumably, this is also a warning about the potential risks of buying unverified parts off for fleaBay, rather than a reputable UK supplier? It also suggests that it's a good idea to wire up and test the circuit -- resistance testing with a multimeter -- before fitting inside a vehicle. Any advice on this, Mick?

Yes, the references you sent are very useful. Thank you for digging them out.

What would be really useful would be a table giving the Amps info from the reverse of the 90-110 Fuse box cover, correlated to the Amps ratings printed on the glass and equivalent spade fuses. E.g. if the fuse box says 7.5A, then I believe that the correct glass fuse is marked 15A and the correct spade fuse would be marked 7.5A ? But, although I'm pretty sure on the glass fuses, there may be other factors I'm not aware of for blade fuses. Is this something you could write for us, Mike?

As for reputable specialist UK fuse suppliers, who sell in small quantities. Any suggestions, please? Or is it more of a case of choosing a reputable manufacturer, then looking at who sells them (you did mention manufacturers publish the data on fast blow, slow blow, and continuous current). I guess we laymen could look it up, but you know better what you're looking for.

Any help very much appreciated,
Rick
Click to expand...

A bit like the oxidized contacts on a 30 odd year old glass fuse box.
 
Wow that escalated quickly.

Older Land Rover electrics are bloody simple. All you need is a multimeter.

Orange beacon for recovery? Are you a licensed and trained recovery driver?
 
flat said:
I better bin my red one then. Might need to be licensed to do that though....
Click to expand...
I would. It’s a well known fact that red fire extinguishers make the fire worse because red is a hot colour, blue is a cold colour however and therefore is more effective at fighting fires. Fact. But yes, you do need a blue extinguisher operators license to use one.
 
You must log in or register to reply here.

Similar threads

Alpinewoodsman
90/110 fuse box replacement.
Replies
5
Views
2K
Litch
L
SR4x4
For Sale Land Rover 19 inch Alloys - PCD 5/120 - £80
Replies
0
Views
963
SR4x4
SR4x4
B
P38A P38 2.5 dse engine noise?
8 9 10
Replies
184
Views
16K
Datatek
Datatek
dag019
Hypothetical project feasibility
Replies
17
Views
2K
FlyingPete
FlyingPete
MikeFl4
P38A ABS faults and codes
Replies
17
Views
3K
MikeFl4
MikeFl4