ploughing lamp

Posted by belldesign on 2011-10-24 16:06:00 

I'm fitting a ploughing lamp to the rear of my 885. Can I take the power directly from the rear light wiring loom, or will i need to wire it through a relay.

If it needs to go through a relay, I am also fitting two spotlights to the rear of the cab roof which will be wired through a relay, could I wire the ploughing lamp into this as well?

Thanks in advance for any advice.
Posted by: tractolover on 2011-10-24 16:40:00 
Well its better to use a relay for them and the total current rating of the three items must not go above the rating of one relay.Probably better to use two relays.You can use the tail lights wires to trigger them though, possibly one wire from each taillight for each relay.
Posted by: belldesign on 2011-10-24 17:13:00 
Thanks for that, looks like it's the way to go!!
Posted by: jimc1390 on 2011-10-24 21:45:00 
by triggering the rear work lamps with the rear lights would mean your work lamps would be on when travelling home on the road in the dark
Posted by: belldesign on 2011-10-24 23:05:00 
I aim to wire the work lamps through their own switch so presumably they could be controlled independantly of the rear lights, but isolated by the main switch on the dash. Does this sound like the way to do it?
Posted by: tractolover on 2011-10-24 23:07:00 
jimc1390 wrote:
by triggering the rear work lamps with the rear lights would mean your work lamps would be on when travelling home on the road in the dark
Yes very good thinking there, well spotted.If you connected straight into the tail light circuit, you would still have the same issue.Have to wire in switches to both the ploughing lamp and the spot lights.Wire them into the trigger circuit so the heavy current wont burn them out.
Posted by: Guest on 2011-10-24 23:13:00 
Rear work lamps, which includes a plough lamp, are required by Law to be independently switched as it is against the Highways Lighting Regulations to have them illuminated whilst travelling on the public highway. This also applies to front mounted work/driving/spot lights which are required to extinguish on headlamp dipped beam.
Posted by: Madders on 2011-10-25 00:33:00 
your selectamatic multi position headlamp switch has sides, dip, main, and a position for supplying power to the plough lamp toggle switch....no relay.....unless post 70 they went and got all technical???
Posted by: John_Allen on 2011-10-25 08:56:00 
As Madders says, the correct switch does allow for plough lamp, though my 780 has an MF switch (proper DB ones were difficult to get eight years ago!). My plough light is wired to the main beam circuit so that it is always off when the dipped beam (or sidelights only) is on. It has, of course, its own switch so that I can use main beam on the road and not have the plough light on!

I did think of wiring through the sidelights' circuit, but decided against that as I thought that, if the plough light was required, main beam would be too! It might have saved wire if I'd tapped into the sidelight, but I'd have had to upgrade the wire from the switch to the rear lights to cope with the added current. However, the main reason is that I'd forget the plough light was on and leave the sidelights on when parking up at night - and not notice as the garage light is quite bright!
Posted by: Guest on 2011-10-25 09:13:00 
The plough light, originally, was wired to the sidelight feed. The wiring, single live feed from the multi connector under the seat frame, through the tubing running along the rear of the axle, up through the mudguard inner skin stiffener, through the small hole with a grommet, into the plough lamp body hole, another small grommet, into one side of the switch and from switch to bulb holder. The earth was a short wire with a large ring soldered on which grounded by means of the lamp mounting bolt, the wire entered the lamp body through the same hole as the power feed, at this point power and earth were contained in a 2 core short cable, and connected to the bullet connection on the other side of the bulb holder. The plough lamp when switched on at the lamp switch comes on with the sidelights.
Posted by: belldesign on 2011-10-25 14:11:00 
I've just checked and my switch only has three positions and not four as Madders suggests.I am now thinking of using two relays as tractolover suggests, one for the two new rear work lamps and the other for the plough lamp. I'll probably trigger a relay from each tail light wire. The plough lamp does have its own toggle switch. I'll also probably add an inline fuse to each circuit. Does this sound ok? What size fuse do you think I need?
Posted by: John_Allen on 2011-10-25 17:46:00 
There shouldn't be a need for two relays if both sets of lamps are workign from the sidelight feed. Just put two wires to the lights' switches from the terminal of the relay.

A very quick search produced this relay:

http://www.halfords.com/webapp/wcs/stor ... 65688#dtab

However, a decent relay of 20A or more will do the job - the 55W lamps will require about 4.5A each, but always leave 25% "overcapacity" for safety.

If you do it this way, you can get away with a single fuse (20A or so). However, it would be better to have a smaller (say 7A) fuse on teh plough light and a 10A or slightly more for the pair of worklights.

If you get this sorted, you can come and sort out my Golf's electrics - the "Door open" warning light is on for some reason, which means the central locking won't lock from outside the car! It took half an hour to get the trim panel off the tailgate this afternoon and I can't see anything that I can test!! The VW forum reckon it's likely to be the boot lock's electronics and it will need a new switch (at £120 or so)! I'd leave it, but I'm told the warning light problem is an MOT failure!
Posted by: jimc1390 on 2011-10-25 20:00:00 
ha ha done that eng oil light on abs 1 and 2 on foden, it was test morning and no time to be messsing around
Posted by: tractolover on 2011-10-25 21:24:00 
John_Allen wrote:
There shouldn't be a need for two relays if both sets of lamps are workign from the sidelight feed.
The OP wants to fit 3 lights though, not 2.If the total amp rating is under the relays rating then one relay will certainly do.I am guessing that they all together will be over the rating.Thats why I suggested using two, but by all means check them all first.

its all a matter of taste with regard to where you connect into.You can certainly connect into the main beam also.Me, I like to make things as easy as I can.The reason I suggest connecting into the tail lights is because they are the closest to the rear plough and spot lights.Othewise longer wiring will be needed to connect up to the light switch.