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Twin Rear Fog Light Modification
Yesterday I started a thread decrying the manufacturers of Citroen Berlingos for not wiring in two rear foglights on the Mk2 Berlingo Multispace. It appears that some variants do have two lights that work, others have just the one (O/S in the UK).

Mr Haynes, the font of all knowledge, shows only one light unit wired for rear fogs in his rather excellent (not) repair journal.... on this occasion he is quite right in what he says

I decided to dig a bit deeper today and removed N/S and O/S light clusters to gain access to the wiring and bulb holders. On the O/S a brown wire is present at no.1 wiring pin on the cluster but no wire present on the N/S.

The bulb holder is complete and ready to accept a bulb and there is a connection on the cluster so I have run a cable into the vacant position in the loom-connector and used a minature spade connector to connect to the cluster.

There is already wiring present running from side to side on my vehicle by virtue of having had a tow-bar wired in. It is a simple matter of clipping the new cable to run along the course of the existing wiring and feed up to the O/S where there is already a connection point in the harness where cabling for the towbar wiring is fed off.

The new cable needs soldering or Scotchlocking in to the wire from no1 connection and then insulating with tape or similar. New bulb in holder (21w Single Contact), switch on rear fogs (Now plural) and voila. Examining the exisiting wires before hand they look more than adequate to take the extra current draw. I may uprate the fuse to 15 Amp but no probs with old one yet.

Doing this work has also done may a favour and averted possible future problems as I found and insulated a chaffed wire from where the towbar fitter had made a bit of a balls up job...
Berlingo Multispace 2.0HDI '54 reg Mediterranean Blue
[-] The following 1 user says Thank You to andy-womble for this post:
  • Fido
Nice write up,I can see me doing this in the not too distant.
Will check first just to make sure I've just got the one fog,but guess I'll
Wait to fit my battery first Smile
One point on your excellent write up.:-

A fuse is intended to be the weakest link in an electrical circuit. It is designed to blow before a fault in the circuit it protects causes a current to flow high enough to raise the temperature of the wiring to a dangerous level with the inherent risk of fire. There is no such solution as upgrading a fuse to one of higher capacity or amperage.



If still not convinced
Thank you for teaching granny to suck eggs, I must correct you and state that when a circuit is drawing extra current then surely by virtue of the formula Power in Watts = Nominal Voltage of Circuit multiplied by Current or amperage drawn from the circuit which transposes to give Current in Amperes drawn by circuit = Powere in Watts divided by Nominal voltage. In this case we are doubling the current drawn by using two bulbs so the Amperage rating of the fuse should also be increased. I did check the sizing of cables for adequacy as well....
Berlingo Multispace 2.0HDI '54 reg Mediterranean Blue
So you are saying that if your lighting circuit main fuse at home blew because you installed more lights you would use a higher rated fuse ?
15 amp fuse is more than enough as long as all that it's supplying is the 2 fog lamps....
I think from memory it watts /volts = amps
2x21 watt bulbs=42. 42watts /12 volts = 3.5 amps......
Please feel free to correct me if that's wrong,it's been a while since I dabbled in such work
Mains electrics is totally different and does not have the range of fuse sizes but having checked the size, ie cross-sectional area of the wiring against known information of the current carrying capacity of the cable for motor vehicle applications and finding that it is more than adequate for the purpose of supplying current to two 21 watt bulbs instead of the original one bulb that was fitted, I was then faced with the dilemma that the circuit was fitted with a fuse that was of an inadequate size to suit the uprated application and needed one of a suitable rating to accomodate the extra current flowing through that circuit hence the math as above....

Thanks for that Fido, I was thinking on the side of caution and going by the fuse capacity of say the brake light circuit which has similar sized bulbs and looking at what size fuse had been fitted there but then I forgot that there are now 3 lights on that circuit including the high level brake light.
Berlingo Multispace 2.0HDI '54 reg Mediterranean Blue
In absolutely no way is mains electricity totally different from non mains electricity as employed in automotive applications, only the form in which it is generally transmitted. viz Alternating Current or Direct Current. My comment at 9.24 was wholly concerned with so called " Uprating " a fuse and in that context I refer again to the rather long entry on the subject of fuses -
The electricity may only be different with respect to it's being rectified 12-14v DC in a vehicle and 230/40AC in a house.

The method of distribution of the electricity, however, is very different. A house has one or more protected ring main circuits. Nowadays you no longer find fuses around the
consumer unit (Fuse box) as all circuits are protected by Miniature Circuit Breaker and/or Residual Current Devices. The only fuses are in appliances' 13amp plugs and in some cable outlets.
A vehicle has a series of 'spurs' all individually fused.
It is possible to increase the rated fuse value quite safely in a vehicle assuming that the existing cable in the circuit is capable of handling the increased current without becoming hot or even warm. ( ie resistive)
That's the primary reason for using relays to drive auxiliary accessories such as extra horns and spotlights using supplementary high current cable, usually connected to the battery via a high current fuse to cater for the extra loading.
While the risk of actual fire is minimal, although in extreme cases it may occur, the high current horn or spotlight being connected directly to existing cable and with no relay will certainly not operate as designed due to the voltage drop induced in the existing cable. High current is regarded generally as being more than a nominal 15 amperes
So if you have introduced a new item into your vehicle's system and you are satisfied that everything is connected correctly then start the engine and connect your voltmeter to the terminals of the new item. The recorded voltage should remain the same whether the item is switched on or switched off.
Anything up to say 0.2 v drop may be acceptable but if you're getting a drop of a volt or more then something is wrong.
The Older I get the Better I Was!  Cool
Succinctly put Old' Jeffers
"assuming the cable is capable " is the speculative question and any conductor carrying electrical current will increase in temperature but I am splitting hairs

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