Fuse Box Question....

[Whizz]

Thanks Brock, that makes far more sense. This uses the relays as they are supposed to be used, i.e. being controlled by a low current switch. Sorry to be pedantic Diesel but my job for the last 20+ years has been checking and approving electrical/electronic installation designs made by Grad Engineers for common sense (one of the least common commodities in the world it would appear) and workability, and the original drawing simply didn't look right. Brock has supplied the missing information for switching of the relays.

[Diesel]

.... Sorry to be pedantic Diesel but my job for the last 20+ years has been checking and approving electrical/electronic installation designs made by Grad Engineers for common sense ...

No probs Whizz - thanks for the input - this is why you are a great part of the brains trust around here.     

Now that Brock has hit 60.... yada yada yada....                                   

CHeers, Diesel

[Brock]

Engineers for common sense

Isnt that a tautology, ie  diametrically opposed ideas ?????

[Whizz]

That isn't Tautology which is defined as " (a) The saying of the same thing twice in different words, or (b) A phrase or expression in which the same thing is said twice in different words." However I was referring to the common sense levels of the designs not the Grads, and your prejudice is showing 

[tj189]

I like the idea where Brock has the lights also switched through the main headlight (I thought this was a legal requirement?), however this appears to not allow for redundancy with lighting.  Should the fuse for the driving lights fail then both sets are lost. (I understand that similarly the same could occur if the switched circuit fuse blew), however using the fuse block allows for one set of lights to be lost and still have the other set available?

In essence I would set mine similarly to how Brock has suggested but run the two sets of driving lights to separate fuses on the secondary fuse block and still have Diesel's separate switch for each set of driving light (thought this was a legal requirement as well?)

[saaz]

The way I have mine set up is a common main power wire up to the front, protected by a fuse, then a fuse box that feeds power into each of the various circuits. The idea, as TJ says, it to have only one circuit go if that is the problem, rather than the main fuse taking everything out.  Similar to how Honda set things up originally.  My headlights can only come on with the ignition, and the driving lights only if the headlights are on high beam but this is optional through a switch.

I also have built in the ability to not have all those circuits on while the ignition is on. Main reason is so I can start the bike without stressing the HID headlights, but also so I can keep the ignition on without the bike running and use the autocom for the UHF and mobile without flattening the battery and having to take out the earplugs etc.  This would have been handy one time in the dark to call ahead using the mobile through the Zumo to get a keysafe code from a caravan park without having the noise of the bike running and trying to tell the number to another rider to use on their phone then try and find a pen etc etc!.  Also handy if you want to stop and contact someone via the UHF or mobile.

I also have the original headlight circuit in place so can put in H4 bulbs if necessary.

I am hoping that this built in redundancy is not necessary as I have not had a headlight or HID fuse go that caused a problem, but I am just allowing for contingencies based on past experience.

[saaz]

While we are on interesting wiring ideas, and some professional elec types are watching, is there any technical difference or practical downside to using a switch controlling a relay to interrupt the ground feed as opposed to the switching power feed?  I wired my most recent effort up to switch the ground on and off to the relay powering up the main power fuse box for the HID lights. My main reason was that is is probably less likely to cause problems with potential shorting out possibilities to have the ground wire switched than feed a live power feed through the switch.  The less live wires routed around the bike the lesser the risk.

[Brock]

As one of those professional types, (RAAF trained Avionics Tech) I will answer those questions.

Mechanically there is little difference between switching power, and switching earths. 

With the aim of removing power wires, cant be done. You have to have a live feed to the item you are powering. You can place a fuse block close to your equipment, with a long single run to the battery and short leads to the load.

Switching power, applies power to the item from the switch to the load, allowing current to flow through the load and to earth. Turn off no power, and no flow.

Switching earth, allows the power at the load to supply current through to earth. Sounds the same doesnt it, but its not. The power is always there looking for a return path to ground. should the return (earth side) wear through, it could allow a good, or a poor (high resistance) path to ground, possibly causing heat, fire or drained battery, if its a hot item like a UHF wired directly to the battery. A stray earth (as it is called) will cause an item to be on wether you want it or not.

A worn through power wire will cause a short and blow the fuse.

It gets hard to explain this stuff, as I have been doing it for 40 yrs, and to me its inbuilt knowledge that can be hard to dig out.

[saaz]

I makes sense to me.

 The switched ground I am using is not a main power, but the switching power used to trigger the relay.  There is already a fuse protecting the switching powered circuit  (ie original Honda wiring).  In my laymans logic, the power will try and find a return path to ground at the switch or later down the circuit at the relay if using switched power.  By taking the power just to the relay, it will try and find ground there only.  All depends on the circuit I suppose.  I can always rewire it the other way around if that is better.

I found out it worked as I tried to reuse a 40A relay that was on the bike with the police wiring. First time I turned it on the main 30A fuse went as did the tailight fuse.  Ditched that relay and works fine.  At least I have a few new fuses on the bike!

[Brock]

Earth switching for a relay is acceptable when going for a particular outcome. For example, the side stand switch mod to isolate the HID headlights when starting on the 1300 ( havent worked out one for the 1100, no one asked for it)

[saaz]

That is probably the closest to what I am trying to achieve with the manual switch.  Think of it as a sidestand down situation, except when the sidestand is not down.

Earth switching for a relay is acceptable when going for a particular outcome. For example, the side stand switch mod to isolate the HID headlights when starting on the 1300 ( havent worked out one for the 1100, no one asked for it)

[Brock]

Think of it as a sidestand down situation, except when the sidestand is not down.

 

I see you are really a gorgeous blonde then..   

[Yorkie]

Almost all cars built in the last 10 or so years are switching the earth, I don't believe it is good practice as in the event of an accident a shorted earth cable can draw huge current through other devices and cause them to burn out,

[winston66]

 
Winston66
I believe that Brock has it right.
My limited experience with automotive wiring tells me that in many  automotive applications  a switching  ie. (activating)device of some sort   be it either a relay or switch of some sort can be placed in the netural or otherwise earth return side of the circuit.That is between the device which has a positive feed to it and the its respective earthing point
It seems to me that this convention is done by the automotive people mainly to .
1  Sometimes simplify some of the complexity of some of the various circuits that they are trying to controll.Ie. the reversing motors that raise and or lower the car windows these motors  can have seperately wound directional field windings which controll the rotational direction of the motor. Simarly some multi speed windscreen wiper motors have different earthing wires which are switched independatly in order to alter the motor speed .
2  Possibly to economise on the cost of the installation, I am not quite shure how though.
3  An attemt at confusing the average person who is generally taught that for electrical safety (ie. normal house hold 240 volt wiring and appliences , That the switch or isolating devices must be placed in the positive or as otherwise what is known as the active feed to the device or appliance.
 Another thought that I have about fuses in automative situations is that their main purpose is to protect the wiring harness in the event of a catistrophic shorting out of the main current carrying wires to an un intended earthng point thus causing overheating and a possible destruction of the associated wiring. So therefore I generally do not try too hard to match the fuse to closley to the intended load and consequent current draw through the respective power feed, so in the main I will for instance put in a 10 amp fuse when I am working on an anticipated 5 amp draw. However as Brock says it is imperative that the fuse is placed as close to the start of the respective power feed as possible .
 You know that it is all smoke and mirrors and it realy is majic stuff.
Cheers to all.
Winston 66 Northampton

 

[Brock]

I dont know of any cars these days that switch earths, gut I know that the Datsun 1600 did, gave me a headache at the time trying to get a mates driving light to work till I figured that out...

[Whizz]

Whilst from a theoretical viewpoint the placement of the switch can be on either the live side or the neutral side of the device and it will work just fine, from a design viewpoint it is not correct to wire the switch on the neutral side. This is because if you switch off the device by breaking the neutral return, the device is still live and can be prone to seeking earth returns through any number of other devices. This does happen and parallel earthing can be a real bugger to find and fix. Switching the neutral side can be dangerous because of the possibility of short circuits causing systems to come on unexpectedly and can be disastrous in the case of an accident. In short, yes it is possible, but most definitely not recommended

[saaz]

   Well, I was trying to keep it real simple for you

Think of it as a sidestand down situation, except when the sidestand is not down.

 

I see you are really a gorgeous blonde then..   

[Whizz]

Yorkie, I'm not sure where you get the idea about cars switching the earth returns, I've not seen any that do unless, as Brock says, it's for a specific purpose.

Ever seen the result of someone removing the wrong battery terminal first, then welding the spanner to the frame in a huge shower of sparks? Because I have and it wasn't pretty!

[saaz]

I suppose the other side of this is that the live wire if switched will be live at the switch, so also always seeking ground as well.  So not much difference to being always live at the relay switch side  or at a switch.  For situations other than turning relays on or off, I can see that ground switching might not be the best idea.

Whilst from a theoretical viewpoint the placement of the switch can be on either the live side or the neutral side of the device and it will work just fine, from a design viewpoint it is not correct to wire the switch on the neutral side. This is because if you switch off the device by breaking the neutral return, the device is still live and can be prone to seeking earth returns through any number of other devices. This does happen and parallel earthing can be a real bugger to find and fix. Switching the neutral side can be dangerous because of the possibility of short circuits causing systems to come on unexpectedly and can be disastrous in the case of an accident. In short, yes it is possible, but most definitely not recommended

[winston66]

 

Winston66
Brock,
Think of the ecu in a car  and for instance the coolant temperature detector in the block , a one wire device,this acts as a variable load in the respective earth circuit and is connected directly to the respective switching (monitoring)circuit in the ecu in order to controll the programme for the duty cycle of the fuel injectors when the coolant is cold and alters as the motor warms up ie the old fasioned choke controll for a cold motor start.
 Also I believe tha many cars run an active loop around all of the courtesy lights and these are then switched on either individualy or otherwise as a group by being grounded by the actuation of the respective door switch earthing out when a door is opened.
Cheers to all
Winston66 Northampton
 

[STeveo]

(Ever seen the result of someone removing the wrong battery terminal first, then welding the spanner to the frame in a huge shower of sparks? Because I have and it wasn't pretty!
[/quote]

As an apprentice I dropped a 1/4 drive socket bar into the electrical panel of a DC3 an although only 28volts, the amperage across the bar heated it to the point of melting the end off it. I learned some new words that day from the sparkys. 

 

[Yorkie]

As Brock says, try wiring up driving lights on any Jap or Korean vehicle and the conventional way doesn't work because they are neg earth. I believe Australian manufacturers are going this way also, no idea why although Winston may have a point with what he says.

[STeveo]

Been negative earth for a bloody long time. Every vehicle I've ever owned or worked on has been neg earth, only old pommie stuff has the other way round, jap bikes have all been neg earth.

 

[Brock]

Im pretty sure that today every thing is -ve Earth, (+ve earth went out a long long time ago), and that most of the switching in cars is done with the positive line. Only a few things light courtesy glovebox and boot lights are earth switched.

[Tipsy]

  py

Earth = what I walk on
           grow veges in\
           sometimes get covered in

Positive = Out riding with friends on our wonderful machines
               Having a few stubbies at Home listening to music
               Having a few drinks & BBQ with the Ostoc crowd

Negative = NOT HAVING ANY OF THE POSITVES

Tipsy

I could or not (relay) to this