Hello,
First the purpose of a fuse is to protect the wiring not the component.
That said, a 50A fuse will undoubtedly in almost all cases protect all
wiring if a circuit is shorted to ground (the fault is near instantaneous).
But it can never protect the wiring of a circuit that has wiring rated for
20 amps, if the failure is a slow cooker in the 20A circuit drawing say 30 A
or so caused by who knows what. Maybe a loose or corroded ground or loose
or intermittent hot circuit connection. That is until the insulation melts
through and the hot lead conductors ground them self and cause the 50A fuse
to blow. But by that time the damage has already done. Now on the bright
side, the melted wiring will be of great help in diagnosing just where the
problem circuit is located.
Molon Labe
_bill
-----Original Message-----
From: josef-eckert@t-online.de
Sent: Thursday, December 17, 2015 1:42 PM
To: Roger Grace ; Healeys, Forum
Subject: [Healeys] New Classic Technologies Fuse Box
Roger,
When I have a direct short cut it doesn´t matter if its fused with a 5 Amp
fuse or a 35 Amp fuse. Both melt in milliseconds before the wiring gets even
warm, certainly not melts.
But if you feel more safe adding additionaI fuses I do not mind. I only
would spend my time and money in other things which I see of more benefits.
Josef Eckert
-----Original-Nachricht-----
Betreff: Re: [Healeys] New Classic Technologies Fuse Box
Datum: 2015-12-17T18:08:40+0100
Von: "Roger Grace" <roggrace@telus.net>
An: "josef-eckert@t-online.de" <josef-eckert@t-online.de>, "Oudesluys"
<coudesluijs@chello.nl>, "Healeys, Forum" <healeys@autox.team.net>
Josef,
The process of using branch circuits with multiple fuses (or breakers in
industry) is called protective discrimination.
If done properly, the lower rated fuse will rupture before the higher rated
one above it in the chain.
Just like in your house - a fault in your garage that trips that breaker
does not trip the main incoming breaker.
This avoids the problem of a faulty minor circuit taking out the whole
electrical system (car in this case).
In addition, what is often overlooked, is the fault current rating of the
conductors.
For example, if a small current circuit e.g. radio with say 20 AWG wire
(adequate for current rating) was only protected by a single upstream high
rated fuse, in the event of a short, there could be the risk of the wire
and its insulation melting before the fuse ruptured with catastrophic
consequences.
This is likely the most common cause of disastrous smoke shows.
Having said this, our cars' electrics is reliable and faults are few.
So, in summary if you are making changes to the wiring, more circuits with
properly rated fuses (for load) and conductors (for fault current) are the
best protection.
rg
-----Original Message-----
From: josef-eckert@t-online.de
Sent: Wednesday, December 16, 2015 10:32 PM
To: Oudesluys ; Healeys, Forum
Subject: [Healeys] New Classic Technologies Fuse Box
Kees,
Sorry, but you wrote switches are old and have worn a fair bit.
That may be right, but when you have a look to the internals of an original
Austin-Healey ignition switch or light switch, the contact design and
switching abilities are far superior to anycar box relay you get in today´s
market. So they are more than capable to cope with the high currents. Its
different with i.e. MG B switches used in the 70s.
You also wrote:
Also having only two large fuses causes a lot of damage when something goes
wrong and there is a short.
I see you are not much in electrics. It doesn´t matter if you have 2 or 30
fuses in your car. When there is a short and the line is fused, via one of
the 2 or 30 fuses, the fuse blows and no damage is caused. So when you fuse
each line seperately there is no improvement. Critical are those connections
which are not fused at all. There I see an improvement with additional
fuses. But there are only two or three additional fuses needed, when you
want to savegard this.
The original electrical system of my original Healeys are more reliable as
any of my modern cars. To my opinion many fuses do not help, the cause even
more trouble.
Josef Eckert
Germany
-----Original-Nachricht-----
Betreff: Re: [Healeys] New Classic Technologies Fuse Box
Datum: 2015-12-16T22:24:53+0100
Von: "Oudesluys" <coudesluijs@chello.nl>
An: "healeys@autox.team.net" <healeys@autox.team.net>
A good idea to save old technology. The switches are old and have worn a
fair bit. They have a higher resistance than when new so they develop
more heat and get damaged that way as they carry the full brunt of the
circuit they are in. Using relays means that only a very low current is
going through the switches without developing a lot of heat. Also having
only two large fuses causes a lot of damage when something goes wrong
and there is a short. Burnt wires, ego or perhaps the car. Anyway a lot
of money and time is needed to rewire.
The more modern approach with a proper fuse/relay box will take a fair
amount of time and some money to install, but it puts your mind at ease.
Kees Oudesluijs
Op 16-12-2015 om 20:07 schreef Linwood Rose:> Every now and again those of
us involved in the restoration of our vintage cars come upon new products
that exceed expectations. That has just happened to me and I wanted to share
some news about my finding. I have absolutely no financial interest. Those
of us who have 60s era cars are used to the ubiquitous two fuse Lucas fuse
box, and how limiting it is. A fellow named Marc Goldblatt, A mechanical
engineer and owner of Classic Technologies, has developed a very compact
Fusebox consisting of seven relays, 15 fuses and 34 wiring positions
perfectly suited for our cars and at a very reasonable price.>>> Mark is
actually working on the restoration of his own Big Healey right now. In
addition to the fuse box Marc provides a fantastic wiring schematic and
directions and he will also help with the development of a custom wiring
harness. Alternatively, great directions are provided for adaptation of the
box to an original harness already in place in the car.>>> I have just
installed one of Marc's boxes in my current project, a 1964 Jaguar Mark 2
and I am a very happy and satisfied customer. I only wish that he had his
fuse box on the market when I restored my Healey. Anyway, check out his
site, I think you will like what you see.
http://www.classic-technologies.com/>> Lin> 1959 AH AN5 Bugeye> 1960 AH 3000
BT7> 1964 Jaguar MK2> 1969 MB 280SL>
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