I haven't been keeping up with this discussion, so I don't know what's been
said.
However, I don't think anyone has been picking on Lucas fuses. In fact, the
problem is with US fuses. Lucas fuses show the current at which they're going to
blow. US fuses show the current at which they *won't* blow. A lucas 35 amp fuse
is
marked 17 amps continuous. Therefore the equivalent US fuse would be 17 amps.
I've examined Lucas fuses and know this to be so. Even tested a few out of
curiosity. And I know the specs on American fuses (Littelfuse) because - tada!
I've been an Industrial Control system and Power Electronics designer for 25
years. I have this discussion about US fuses at work every time we design a new
product.
The US standards are different and I must admit, not as clears as the UK.
TriStagReg@aol.com wrote:
> Okay Guys,
> Now you guys are gonna tell me that Lucas totally ignored standard
> electrical practice when they designed a 35 amp fuse??? In particular,
> British Standards in effect by law at the time, plus IEC and NEC standards
> that have been in place since the 1950's? Come on guys, this ain't rocket
> science. If a 35 amp fuse does not open at 35 amps at the rated voltage,
> plus design tolerance, I'm gonna own that company's assets when it burns up
> my device.
>
> For all you tech weenies out there, this and all British fuses were
> required by UK law to conform to British Standard BS 4265:1968 (originally
> enacted in 1960) subsequently replaced by BS 4265:1977 ( IEC 127:1974), and
> replaced again by harmonized standard BS EN 60127-1:1991. These standards
> define the tests that a company is bound by law to perform and record to
> verify the fuse performs as designed, that is to open the circuit at the
> design rating and labeled rating.
>
> I might buy this pile of malarkey if:
> 1. I was not an Electrical & Controls engineer for the last 25 years;
> 2. A majority of my business was not standards application;
> 3. I saw some documentation from Lucas that says: "This 35 amp fuse will
> not blow at 35 amps" which in itself presents a liability problem, and Lucas
> would have been put into receivership years ago.
>
> There are different types of fuses. Immediate or quick acting, and
> delayed acting sometimes called slow blow or timed acting. A fuse or circuit
> breaker must also be designed with a set of tolerances, guaranteed to open
> when at the labeled design rating plus the required tolerance, usually 5%.
> If a fuse or circuit breaker does not open at the stated rating, things burn
> up. The purpose of a fuse or circuit breaker is to protect the wiring and/or
> the device, depending on where the fuse is placed in the circuit. Improper
> selection of the correct fuse for the application is where things go wrong.
>
> Now I might buy that Triumph, Jaguar, MG did not properly select the fuses
> for each circuit in their cars, evidenced by the amount of melted wires I see
> in those cars. But then again, every wire I have seen melted has had a fuse
> that was either bypassed by wiring to a non-fused circuit somehow by addition
> of an accessory, or fused with a larger or incorrect type fuse than the
> circuit or wire was rated or designed for.
>
> Any Questions?
>
> Regards,
> Glenn Merrell
> Triumph Stag Register USA VP
> mailto:TriStagReg@aol.com
> <A HREF="http://members.aol.com/tristagreg/";>Triumph Stag Register Web Page</
> A>
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--
George Richardson
The Wyvern - '57 Triumph TR3, TS15559L - http://www.merlingroupinc.com/tr3.htm
The Hippogrif - '71 Triumph Stag MKI, LE8176E - soon to get a site of it's own
Kitty - '83 Jaguar XJ6 Vanden Plas - Daily Driver (when running)
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