Fuse on Earth Side |
Post Reply | Page 12> |
Author | |
rbt1548
Senior Member Joined: 19 Nov 2014 Location: Glasgow Status: Offline Points: 1241 |
Post Options
Thanks(0)
Posted: 10 Feb 2017 at 18:37 |
I'd imagine this is a fairly simple question for all you electronically minded people out there to answer, so here goes.
It's for my BSA Lightning Clubman not my Guzzi so please bear with me. I have uprated the electrics to 12v and I am going to go NEG- earth, rather than the Pos+ earth which is standard on the older BSA bikes. I decided also that I wanted the ancillaries, lights, horn, stoplight etc. to come on after the ignition was switched on rather than the way it was originally wired where they could be operated straight from the battery, this prevents somebody playing about with switches when parked up leaving you with a flat battery. Deciding to do all this, I thought I would get a wiring loom made up professionally incorporating all the changes that I wanted, the wiring loom that was made is top notch, a well made item that I am pleased with, with separate mini looms for ignition etc. The only thing I'm not sure of is the fuse has been put on the earth side, (between the battery and earth), rather than where it normally is on the live feed side. Question.... will it make any difference and should I remove it and wire it in to the live feed side ? All opinions welcomed. Thanks!
|
|
1975 Honda CB750 K5
1958 Wife It wisnae me, a big boy done it and ran away! "I was so much older then; I'm younger than that now!" |
|
red leader one
Senior Member Joined: 07 Oct 2014 Location: Cullercoats Status: Offline Points: 4466 |
Post Options
Thanks(0)
|
iceni
Senior Member Joined: 16 Sep 2014 Location: Colchester Status: Offline Points: 2480 |
Post Options
Thanks(0)
|
There's no such thing as a simple electrics problem - at least not for me! I've recently swapped my Douglas for a BSA Gold Flash, which arrived with several problems, one of which is that the ammeter shows no charge.
Removed dynamo, tested all ok, comm, field coils and brushes. Dynamo runs as a motor in the correct direction, but doesn't charge. RLO's link is a good source- it's what I've been referring to throughout my saga! I'd put the fuse on the live side, but what the hell do I know ⚡️ |
|
Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17637 |
Post Options
Thanks(0)
|
So long as there are no stray connections between the battery negative terminal and the frame, the fuse will work just as well there as anywhere else.
The danger would come if somehow something bridged between the neg. terminal and frame and something else happened which ought to blow the fuse, as the fuse wouldn't blow in that situation. But as the chance of that is almost negligible, I wouldn't worry about it.
|
|
Brian.
Better 5 minutes late in this world than years early in the next. |
|
motopete
Senior Member Joined: 18 Aug 2015 Location: Notts Status: Offline Points: 532 |
Post Options
Thanks(0)
|
Wot he said
I might be inclined to add a label near the battery indicating the -ve side is fused. PS. Electronics is my game
|
|
iceni
Senior Member Joined: 16 Sep 2014 Location: Colchester Status: Offline Points: 2480 |
Post Options
Thanks(0)
|
You learn something new every day. Thankyou
|
|
Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17637 |
Post Options
Thanks(0)
|
Don't think of doing this at higher voltages though.
Came across an installation where the fuses were in the neutral side, which meant if you touched live and an earth, or shorted same, no fuse would blow. At 12 volts it wouldn't do any harm.
|
|
Brian.
Better 5 minutes late in this world than years early in the next. |
|
rbt1548
Senior Member Joined: 19 Nov 2014 Location: Glasgow Status: Offline Points: 1241 |
Post Options
Thanks(0)
|
Thanks to everyone, wasn't sure if there would be a difference, and in my opinion I would rather ask than horse on and make a pigs ear of it!
Motopete , I already have a sticker on the oil tank at the battery saying negative earth, so another one won't be a problem, BUT what will the rivet counters say? Brian, just to clarify, I am making my negative the earth so the fuse will be there,(as it is per new wiring loom). I had on other older bikes, run separate earths from the headlight, tail light etc to a central earth point on the frame because of notoriously dodgy electrics on older bikes, for example trying to get a good earth in the headlight when it's trying to earth to the frame through greasy steering head bearings! Would it still be ok to run an earth wire from individual items, say the tail light? I will be running a good earth wire from the engine to the frame as well so not just relying on a, hopefully, good connection between engine and frame by a attaching bolt.
|
|
1975 Honda CB750 K5
1958 Wife It wisnae me, a big boy done it and ran away! "I was so much older then; I'm younger than that now!" |
|
Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5572 |
Post Options
Thanks(0)
|
You can put in extra earths, it's a good idea.Particularly circumnavigating the steering head bearings
|
|
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
|
Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17637 |
Post Options
Thanks(0)
|
Put in as many earth connections as you want, but only one from the battery to an earthing point with the fuse inline.
|
|
Brian.
Better 5 minutes late in this world than years early in the next. |
|
rbt1548
Senior Member Joined: 19 Nov 2014 Location: Glasgow Status: Offline Points: 1241 |
Post Options
Thanks(0)
|
Thanks Brian, will do. I take it that's because if I did put another earth wire from battery to an earthing point the wire would be heavier than the fuse and it would still complete a circuit but the fuse wouldn't blow? Thanks again everyone for your help, I think this electrical numpty is getting there slowly............. a fuse is there to keep the smoke in the wiring!
|
|
1975 Honda CB750 K5
1958 Wife It wisnae me, a big boy done it and ran away! "I was so much older then; I'm younger than that now!" |
|
Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17637 |
Post Options
Thanks(0)
|
Yes, another earth wire from the battery would render the fuse obsolete.
|
|
Brian.
Better 5 minutes late in this world than years early in the next. |
|
iansoady
Senior Member Joined: 23 Jul 2017 Location: Redditch Status: Offline Points: 2402 |
Post Options
Thanks(0)
|
I always put a fuse on the earth side after once managing to bridge between the live and the frame and melting half the harness of my Matchless G80. But I always also put one in the live side. Both as close to the battery as I can.
|
|
Ian
1952 Norton ES2 1986 Honda XBR500 1958-ish Greeves/Triumph in progress |
|
Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17637 |
Post Options
Thanks(0)
|
What type of fuse? With electric start you will have something like 200 amps flowing, which needs a very hefty fuse. not applicable on a Matchless of course.
Also remember every fuse comes with potential poor connections later.
|
|
Brian.
Better 5 minutes late in this world than years early in the next. |
|
iansoady
Senior Member Joined: 23 Jul 2017 Location: Redditch Status: Offline Points: 2402 |
Post Options
Thanks(0)
|
Yes, with electric start it's more difficult unless you have a separate cable from the battery to earth as well as the heavy one for the starter.
As the question related to an A65 my answer was similarly oriented. I just use water resistant inline fuses as available from Vehicle Wiring Products and others. |
|
Ian
1952 Norton ES2 1986 Honda XBR500 1958-ish Greeves/Triumph in progress |
|
Post Reply | Page 12> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |