The 'E' Type Forum

I am just about to start re-wiring my 1967 V8 , and it came as something of a shock to find that the car comes with only 2 fuses , 35 and 50 amp . No wonder the map light switch has melted! I had thought that the E, with only 7 used fuses , was somewhat mean on this score , but this is very surprising. Can anyone with electrical experience suggest a method of providing more fused circuits without having to alter too much the new loom which I am about to order

You think that is bad - try finding the fuses on a Lotus Elan!

Not sure you should bother Christopher - providing the circuits are protected by those two fuses it does keep things safe, simple and original. Adding extras may only lead to problems later on when it comes to diagnosis. On the other hand it is a fibreglass body which means if it starts to burn it will go completely. Hence there are fewer and fewer Elan's about!

One thought is to fit in line circuit breakers e.g. http://tinyurl.com/3h7t2ed to protect specific circuits.

David : my fault - it is not a Dart but a Mark 2 - now a very rare car as there were only a handful of broad bumpered manual and overdrive cars ( the 250 slim bumpered cars were more common in manual)

Hi Christopher,

When I restored my MK11 which included a new wiring harness, I came across the same problem and wasn't happy with lack of fused circuits in the standard setup, so I just added in-line fuses to the circuits I deemed required separate fuses calculating the loads and fitting an appropriately rated fuse. That was 20 years ago and I have had no electrical issues during this period :)

So does that beg the question of why bother with extra fuses if you have not had a problem in 20 years?

Sorry David, don't agree......less fuses may be simpler, but not safer. Firstly, a minor cicuit which may only draw a small current, let us say 0.5Amp or similar, may develop a fault condition that takes it up to a, let us say 15-20Amp condition, but not a dead short, and overheat to a potential fire situation.....I think Christopher alluded to one such (map-reading lamp melting.....?) The poit is, of course, that the 35Amp fuse he has will not "see" this condition, and snooze on without doing anything...
Secondly, and whilst it may not seem immediately relevant, most classic Pommie (oops.....! Sorry....British...) motorcycles of the 50's and 60's had only one large fuse between the battery and the rest of the wiring. Simplicity....? Yes. But a shorting fault anywhere on the machine meant that you had, instantly, no lights, no ignition (means no engine). When you are cranked over on a tight bend at 60mph on a dark wet night, and this happens, I can assure you this lends a completely new aspect to life in general.....Something about all your eggs in one basket comes to mind. In my motorcycle restorations, I sub-divide into 4 or 5 fused circuits, e.g. lights/ignition/indicators & stoplamps/horn, thus keeping the vital functions separate.....(Why the horn, I hear someone ask, well, because it takes more current than any other device on the motorcycle, and those made by Lucas in the 60's were prone to developing short faults, with age....)As for diagnosis, David, I clearly label the new set-up, whether car or mororcycle, easy as.
Christopher's problem is a bit different, in that the wiring on his Daimler V8 is a lot more complex than a 60's motorcycle, and to bring back all the circuits to a common fusebox/area means massive modifications to an otherwise perfectly good new loom, so in-line fuses appropriately labelled are the only solution, as JEP41 suggests. The in-line breakers are nice, but a bit over the top, and at 15 quid each, well..........
The other aspect of this subject I should like to touch on is the fuse type used on the E-Type. I am replacing all of the silly little glass tube type with a modern 2-spade type. These have a much better contact area, and are colour-coded for easier replacement on the dark wet night I spoke of earlier. One must consider that the fuse-boxes on the E-Type are up to 50 years old, and the corrosion on the contact area of the ends of the glass fuses can be considerable. This raises the resistance of the junction, which raises the heating, which raises the resistance, and on we go.....On removal of the fuse units from my Series 1 2+2, I noted a melted hole where the end of the fuse used to be, on 2, yes 2, of the blocks. I took a photograph of the units, to underpin my case on the Forum, but being somewhat down on IT and PC skills, don't know how to attach it. Perhaps if I send it to Christopher, he might be kind enough to add it later...........
On a general note, the restoration moves on....I removed the diff/suspension/brake unit yesterday, and the wiper mechanism the day before. The former was a lot easier than the latter.....!
Regards to all,
Norman

Hi David, again.....
Just sitting here reviewing my (probably somewhat tautological/pleonastic....) response to the above subject, realized that I hadn't really addressed the, quote "So does that beg the question of why bother with fuses if you have not had a problem in 20 years?" unquote, question you posed. Mmmm....action, inaction, consequences......have you read Pascal's Wager......?
Best regards,
Norman

Can't agree with your reasoning Norman, sorry. If Jaguar reckoned, despite working with the Prince of Darkness, the car only needed two fuses why on earth would you want to complicate matters by changing the loom to incorporate more?

Let us for a moment consider the E-Type electrical system which has no less than eight fuses. More secure? Not really as all the fuses are either 35 amp or 50 amp which are the same ratings as the two on the V8. The only benefit of the extra six fuses is it splits the circuits so failure of one still allows other ancillaries to operate - a sort of limp home mode - although the logic behind the grouping is somewhat suspect. Failure of any fuse in an E-Type is probably going to strand you depending on conditions (dark, raining, heavy traffic etc).

At the end of the day the two fuses protect the V8 just as well as the eight fuses on the E-Type.

A fuse is a deliberate weak link in a circuit to protect the cable.
How can this be achieved if the fuse has a higher current carrying capacity than the cable it is supposed to protect?
If it is not necessary to fuse all circuits with the appropriate rated fuse why do houses have a consumer unit full of them when one or two large ones would do?
Who would like to fly in an aircraft which had the engine ignition and instrument power supplies, for example, on the same fuse as the loo lights?
Maybe it's a matter of the consequencies of failure. If your house or your plane catches fire that's a big deal but if your car goes up in flames so what?

Well, I'm glad I raised this subject, because I think it is an important one in terms of upgrades which contribute to safety. Norman's posts raise two important points : 1. is a lack of redundancy where there are only 2 fused circuits , leading to the possibility of effective total electrical failure at night . 2. is just as important from a safety viewpoint : a circuit which can produce a total short leading to fire with only, say 15 amps running through it, is largely unprotected by a 50 amp fuse , which is probably what led to the melting of my map light switch and ( which I did not mention in my original post) the burning out of the wires leading to it . The interesting thing is that, as Norman posits, neither of the fuses had blown .

By the way, I do not subscrbe to the "Prince of Darkness " jibes which have become so fashionable. In my 1.5 million miles of motoring over 50 years , I never had any Lucas failures except in one very specific set of circumstances : my 3 Triumph 2.5 PIs in the late 60s and early 70s all suffered from the debacle of the converted wiper motor being required to produce, continuously, 106 lbs/sq.in fuel pressure, and they were not equal to it. The problem usually manifested itself with full load misfires, and poor cold starting in winter . In all other ways, my first 1/2 million miles motoring were all on Lucas electrics, which were exemplary . Bosch, however........

Referring to Peter's posts, in my time in aviation , my only actual as opposed to simulated emergency was in fact an electrical fire, and it is, as he suggests, not something I can recommend , although in fact no harm resulted apart from a great deal of alarm resulting from the fire engines , complete with men in those silver suits, pursuing us down the runway !

Going back to the original subject, I shall try tomorrow to reproduce Norman's photo of a melted fuse box

Hi David,
Regret cannot possibly agree.....However I consider Christopher and E-bygum's comments cover pretty well anything I could say in addition. Is there any truth to the rumour that Arthur Whittaker was offered a bulk discount on half a million 35A fuses, and half a million 50A, in the late50's/early 60's, thus determining the level of protection for years to come........? Just joking....really liked the comment on the plane loo lights.
More modern practice reflects my opinion on this, my wife drives a 2007 ********, and I note it has no less than 12 fuses (plus 4 spare slots...!). They range from 5A to 40A, and are neatly labelled......and accessible...
Best regards to all,
Norman.

Is the 50 amp fuse in the V8 protecting anything other than the the horns? Presumably all other circuits are on the one 35 amp fuse.

E-Type:


Are we now seriously suggesting re-rating or adding additional in line fuses on our E-Type's 'just in case'? There is probably more risk of fire from owners fitting modern high output alternators without upgrading the associated wiring.

Hi All......Just to add some comments......a few years ago I had lots of smoke & near flames from under the dash of my Audi 80 which had fuses for everything......the fault was the common earth point where many of the circuits were terminated to a body earth stud...the nut was loose therby causing a high resistance & heat which caused all the earth wires to melt & burn......no fuses blew as there was no short.......Just to make the point that a fuse will only protect a circuit from a surge or short....& will not protect from high resistance (burning) which many of our older cars can easily suffer from......make sure that all connections are sound especially at the fuses where the fuse holders can become weak & not make contact with the fuses very well.......give a good spray of WD40 or similar over the rear of the instruments & fuse panel & all electrical connectione to drive out moisture & prevent corrosion/high resistance circuits.......Steve

Hi all again,
Definitely my last words on the subject.....!! mgcjag (Steve) reinforces a point I made along the way regarding fuse-holders, with age they can become one of the danger points in any "protected" circuit. If Christopher manages to post the photo I sent, you will see what I mean. As for David's question as to whether we are suggesting additional line fuses for the E-Type, I don't recall anyone suggesting that (least of all me.....!) Re-rating them to give an additional margin of safety....? Yes, and I shall, on mine. I shall now refer to David's table of circuits and their related fuses. Headlamps....on original equipment, about 55 or 60 Watt on main beam (dip slightly less....) So we have 2 of them, call it 120 watt, by our good old friend the W=VI formula, we have 10 Amps....in my book, I would protect that with a 15Amp fuse, 20 Amp if I was in a really pessimistic frame of mind. But 35Amp....?
As I recall, this post started with Christopher's query and concern (well-founded in my view.....for what it's worth....) on his V8, not a dissertation on the E-Type's set-up. However, I do think that valuable comment comes out of our digressions from time to time....!
A propos David's comments on the dangers of fitting uprated output alternators, I would agree in part, ie, that unless one has greatly increased the electrical loading on the standard E-Type, it is (a) quite unnecessary, and (b) would never reach its uprated wattage or amperage unless jump-started with a flat battery and all the additional stuff switched on immediately..........
Good-night all (Oz-time.....!) and
Best regards as always,
Norman.

Increasing the power generating capacity of an electrical supply will in no way increase the risk of fire in the circuits connected to it.
Fire is caused by heat, heat is caused by current, current depends on load.
If the load draws a current which is greater than the current carrying capacity of the cable then the cable will heat up until the insulation burns or the conductor melts. Nothing to do with the supply.
On the other hand one could fit a fuse with a rating less than the rating of the cable. In which case the increased current drawn by the load heats the fuse conductor to it's melting point before heating up the cable. Et voila no fire.
Where is the sense in connecting a 10A load to a supply using (say) 15A cable and a 35A fuse? Which would blow first the cable or the fuse?

The link to Norman's melted fuseholder is

http://i840.photobucket.com/albums/zz32 ... C00253.jpg

Dealing with Pete's most recent post, whilst his proposition literally is correct in relation to drawn current, it overlooks the fact that alternator output does not just depend on load , but on battery voltage. Thus after a prolonged cold start , a 90 amp alternator may well put 90 amps through the charging circuit even though there is no electrical load other than fuel pump and ignition. if that is going through wires designed for 30 amps, as with the E , sooner or later those wires will overheat, particular if at any stage there is a regulator malfunction

Hi all,
Firstly, thanks to Christopher for attaching those burned-out fuse-holder pics on the Forum, not only did I note 2 of those on the Series 1 I am restoring, but a degree of thermal stress was pretty evident on some of the other fuse clip holders, they were obviously on the edge of failure. In my view, nothing to do with their original design/functionality, just age and corrosion, and increased resistance/heating/potential fire source. It may be difficult for some to realize that the fuse system itself, given poor design and age, may become one of a vehicle's worst fire hazards.
I cannot depart from this subject without an, albeit friendly technical correction, to Christopher's comment that, quote,"alternator output does not depend on load, but on battery voltage", unquote.....In fact, they are one and the same thing.......As the battery voltage drops, after a prolonged cold cranking, or in extremis to flat, the battery acquires a very low resistance, as "seen" at the alternator output terminals, and essentially, it then becomes a very high "load" which the poor device attempts to meet......at least until the battery voltage starts to return to normal (12V) thus increasing the resistance, and of consequence reducing the "load". If there are other circuits in parallel with this primary noble effort, we shall have to go a bit beyond the simplicity of Ohm's Law, and get into the mire of Kirchoff's Laws, assuming that the alternator and the AVC can maintain an ideal of somewhere around 14.3 - 14.7V at its overworked output terminals. So yes indeed, if most of your charging circuit has cabling rated at 30Amps or whatever, it's of little point to attempt to put 90Amps through it. Moral of the story, if you have an uprated alternator (which you probably don't need....) don't do a re-start with a totally flat battery.......
Quod erat demonstrandum,
Best regards to all, 11:00pm over here, had a long day......
Norman

But since the car will not start with even a very low battery, let alone a totally flat one, there will never be 90A, or even close, in a car that started itself, no matter how long the cranking took on a cold morning.

IF you jump-started with a completely dead battery...

WITHOUT waiting a minute with the leads on to wake the battery a touch..

AND immediately disconnected the jump leads once the engine started..

AND expected to drive off at highish revs for max rated alternator output..

AND had every motor, fan, lamp and appliance at full demand.....

MAYBE you'd get your mega-alternator's max output briefly, until the battery took on some charge.

Does anyone actually have a 90A alternator fitted? If so, don't do all the above silly things together. One or two silly things is enough for anyone with a broken-down car that needs external assistance...

Otherwise, as the poster says:

"Keep calm and carry on!" :-)

PeterCrespin wrote: Does anyone actually have a 90A alternator fitted?

Yes, the Americans are quite fond of fitting them. And the battery voltage does not need to be all that low to create a full charge order from the regulator . My quite new battery will drop, post cranking in winter , to about 10.5 - 11 volts without any hesitation - I know this because as a matter of curiosity I measured it last winter . That is quite sufficient a drop to create a full charge demand, and as you know, you do not need high revs to create that output with an alternator, unlike a dynamo. My quite standard alternator produces at least 30 amps at about 800 engine rpm

Hi there Christopher/Peter/all watching.....
Every time I say "this is my last word on the subject" Alas, I submit to temptation, see my post of Sunday August 07... To Peter, yes all the conditions you describe are generally those I described in the last paragraph of my comment of 07 Aug...flat (or nearly so..) battery, jump-start, and immediately try to load up the system with everything on board, including headlights/900W stereo/ heated seats/whatever (on an E-Type...?) Scottish levity prevails.....It won't start on a flat/very low battery...? Of course it will, as we are both ex-motorcyclists, we are well aware that there are people out there that will push/bump-start the thing with assistance from the nearest slope or willing neighbours....The coil doesn't need much to fire up the motor, and off we go into alternator high output, possibly beyond the wiring capability.........
And incidentally, Christopher is quite correct insofar as his comments apply to high output at low rpm, of even the original alternators. This was their primary advantage vs. self-exciting field dynamos, whose Pre-Jurassic characteristics I enjoyed for so many years (!!) on early British motorcycles.....
And enough, hopefully, on the subject, was heading off to become a general debate on current affairs (pun intended .....), but no worse than battery charging (is it not just re-volting.....) groan groan... and not really addressing the original V8 issue, but perhaps it will assist in some spin-off along the way....Always enjoyable..... Just come in from a blast around the block on my rebuilt Triumph T100S, good feeling for a 67-year-old, not quite up to my Series "C" Vincent Shadow though......
Goodnight all from West Oz, keep up the good work....
Norman