Repositioning lights on trailer lighting board - wiring advice?

[Chris152]

I bought one of these recently to attach to the back of our little dinghy:
https://www.amazon.co.uk/gp/product/B002FVP7SC/ref=ppx_od_dt_b_asin_title_s01?ie=UTF8&psc=1

Reading the regs, the lights aren't close enough to the width of our trailer, so they need moving further from centre. I have a longer wooden board that I'll attach the lighting board to, move the lights further toward the edges of the plastic lighting board, and place the triangles and fog light onto the wooden board.

That leaves inadequate lighting for the number plate (the light for the plate comes from the tail lights, a clear lens toward the plate). So I bought two of these, which I'll connect above the plate.


Question - do I simply connect the red and the black wires to the red and black wires (the tail light bulb) here?


And at the other side, does the red of the number plate bulb connect to the 2x red cables, and the black connect to the brown?


I think the question is more about whether this will work in principle - will the number plate lights come on when the tail lights are on? I really don't get electrical circuits. But also I wanted to check the connections are as I've described.

Thanks, Chris

 

[LambCrafter]

Can’t help with the wiring - I would just test it in place and see if it works.

My concern is will the lights you have purchased for the number plate show a white light horizontally to the rear?.It looks like the lens is not shrouded to ensure the illumination would only (in your case) be directed downwards. Just my observation - I wouldn’t wish for you to non-compliant.

 

[Gordon Tarling]

Yes, your wiring assumptions appear to be correct.
I'll also second LambCrafter's concern that the lights you're planning to use will show too much white light to the rear - probably easy enough to fix with the application of a little black tape.

 

[Chris152]

Thanks both.
I hadn't noticed that the white light would show - these were the cheapest lights I could find, obviously not very good! The plan is to only drive in daylight anyway, but since my lad will be driving I don't want to set him up for any points on his license. OK, I think the tape idea should work, if not I'll buy better lights in due course. I'll post a photo once all's sorted.

 

[ChaiLatte]

When you move the light sideways, why can you not move the number plate sideways as well so it stays in the same relative position to the light and is illuminated in the same way?

Is there a regulation that says the number plate must be central? I had a quick look and cannot find anything. Tipper lorries do not have a central real number plate.

I had a further look and cannot find anything that says that if non-central, the plate needs to be biased towards the offside (it looks like the nearside light on the board you have bought has the number plate light provision).

 

[Chris152]

When you move the light sideways, why can you not move the number plate sideways as well so it stays in the same relative position to the light and is illuminated in the same way?

Is there a regulation that says the number plate must be central? I had a quick look and cannot find anything. Tipper lorries do not have a central real number plate.

I had a further look and cannot find anything that says that if non-central, the plate needs to be biased towards the offside (it looks like the nearside light on the board you have bought has the number plate light provision).

Both lights need to move away from centre toward the edges,* so if the plate moves to one side, only the light next to it will be lighting the plate - the light on the other side would now be too far away.

*The regulation says the lights have to be within 400 mm of the outer limits of the trailer.

 

[Tris]

If you've got Eurocarparts nearby pop in and get a couple of these, just the job https://www.eurocarparts.com/p/hella-fog-lamps-driving-lights-482770340

You are right about the wiring, just don't use scotchblocks on a trailer unless you enjoy tracing electrical faults

 

[Chris152]

If you've got Eurocarparts nearby pop in and get a couple of these, just the job https://www.eurocarparts.com/p/hella-fog-lamps-driving-lights-482770340

You are right about the wiring, just don't use scotchblocks on a trailer unless you enjoy tracing electrical faults

Yes, those look a lot better. And we have one in Cardiff, I think.

 

[artie]

An unrelated tip.

If you take the covers of your trailer board lights and smear grease on all the connections and bare wires it will last a very long time.

If you don't the cheapest of cheap chinesium wire will rust through in no time.

 

[Chris152]

I'm amazed, all lights working! We need to make sure it's all weather-proof, and tape over the number plate lights to stop the white light heading backwards, but that's for the morning. Trailer driving tuition tomorrow, soon be in the water.

Thanks all, really appreciate your advice.
C

 

[Sideways]

Check the speed of indicators flashing in case you have a super ancient flasher relay that relies on a bimetal strip and not one using electronics.
Those used to blink faster when you connected extra light bulbs in parallel with the ones in the vehicle.

Shows you how long it is since I wired a trailer socket

 

[Spectric]

Is there a regulation that says the number plate must be central? I had a quick look and cannot find anything. Tipper lorries do not have a central real number plate.

You will find that the only requirement is that the number plate must be clearly visible from behind and be illuminated at night so moving that would be a good idea to locate it next to the light.

 

[Chris152]

Check the speed of indicators flashing in case you have a super ancient flasher relay that relies on a bimetal strip and not one using electronics.
Those used to blink faster when you connected extra light bulbs in parallel with the ones in the vehicle.

Shows you how long it is since I wired a trailer socket

Working fine, in spite of my efforts

 

[Dabop]

Check the speed of indicators flashing in case you have a super ancient flasher relay that relies on a bimetal strip and not one using electronics.
Those used to blink faster when you connected extra light bulbs in parallel with the ones in the vehicle.

Shows you how long it is since I wired a trailer socket

Bimetal strip flashers (they are still being used in many new cars btw if they are using bulbs rather than LEDs) remained flashing at the same speed if you add extra bulbs- they flashed faster if the load DECREASES- ie if you have a 2x21w flasher, and a bulb 'blows' you now only have 1x 21w bulb actually working, and they flashed faster...

(this was actually a legal requirement when bulbs were the only light source btw- in that the indicator system had to show if a bulb was defective by changing the flash rate)

It is also why if you fit 'LED bulbs' to a car with a bimetal strip flashercan, you also have to fit 'load resistors', as the flashercan will see the reduced current of the LEDs as being a 'light out' and make them flash fast...

 

[Dabop]

BTW- there is a 'standard trailer wiring colours' code used in most countries...

Smaller trailers use the 5 core or 7 core trailer cables with a 6 pin or 7 pin plug (round or 'flat' rectangular for the most part, but the rounds can vary in size from location to location), larger trailers like some larger boat trailers, car trailers or caravans often use a 12 pin which has provision for battery charging (either for caravans and boat trailers with a winch- or if the trailer is heavy enough to require 'breakaway brakes' with need an onboard battery on the trailer to activate the electric brakes...)

6 way plug and socket

7 way small round plug and socket

7 way large round socket and plug

This adapter shows the difference in size between the 7 pin small round and the 7 pin large round...

Flat 7 pin socket and plug (the plug plugs into both the 7 way and the 12 way sockets)

Flat 12 way socket and plug for winch/aux batteries etc

It's actually a right pain- I run a small trailer hire company- and depending on the age and where the vehicle is from originally, there is a bewildering array of possible sockets fitted... and I have to carry an adapter like the one shown above for each and every type that might come in...

Luckily, most countries have standardised on the 'flat 7 pin' for all smaller trailers (which is what all mine have fitted as stock)

Many boat or caravan owners also have a set of 'Anderson plugs' like on the far right fitted for an electric winch or heavy battery charging (again, these come in several sizes depending on the amps being delivered- and there is no 'set size' required...)

These are what is fitted to my ute for example- a 12 way rectangular (so fits both the 7 way and 12 way trailer plugs), an Anderson for the winch on the boat trailer and battery charging on the caravan, and a RCA socket (gold plated- at least it is under all the mud lol) for the reversing cameras on the boat and caravan...

Normally the Anderson has also got its cover on, I took it off for that shot (you can see half of it above the 12 way socket with 7 pin trailer plugged in)