I'm adding an ignition switched 12 socket using a piggyback fuse. I've got a suitable fuse in the fusebox but not sure where to ground the black lead of the socket to.
Do I need to find a specific ground point or can I just splice into any existing ground wire? It's a 2003 sprinter with no fancy electronics as far as I'm aware (well all my previous bodging hasn't caused any issues yet!)
Is there usually a grounding point near the fusebox? Im using the one under the steering column if anyone knows sprinters.
Thanks
Any body point will do. There's normally an earth point close by.
I've done two piggy backs for camera's - ground to a nearby fixing screw. That easy. One that goes into any metal framework.
Just go to ground can you not find a ground terminal the radio normally has one close to the head unit .
Ok thanks I'll get the multimeter out and search for a suitable point tomorrow
You don't need a multi meter - just any trim screw into the car body - the ground lead usually has a 'C' spade on for this purpose - quite quickly found a fixing point to pop the C spade on. Steering column, fuse box fixing screws ?
Basically the whole metal frame and bodywork of the car* is Earth. If there isn't a screw already handy then drill a small hole in the bodywork (inside) and put a screw/bolt into that as an earth.
*If is is a glass fibre car such as Lotus or TVR then all the rules change which is why they always have crap electrics. You basically have to run the wire direct to the chassis.
can I just splice into any existing ground wire?
Splicing into another cable is best avoided and in most (all?) cases won't be needed for earthing
I would not piggyback for a 12v socket, someone will go and plug a little invertor or tyre pump into it and you'll damage the fuseboard or wiring loom. Has the piggyback holder got a rating itself...I've seen plenty of pictures of melted ones that have damaged the fuseboard itself.
Use a piggyback fuse, but just as a signal to switch a relay, and heavier wiring back to the battery. And remember, you can only decide on the fuse rating when you know the capacity of the cable, its not determined by the load.
Socket is just for a camera screen, it's got a 12v plug on the end and I think some electronics in the plug so dont want to chop that off. New socket is going to be hidden under the dash by and taped up with the plug on the camera so it won't come apart easily. Piggyback holder has 2 fuse slots for the original circuit and for the new one. I was just going to stick a 3 amp fuse in for the piggyback circuit. Might even have some 1.5a ones I can use
Sounds like you've thought it through, but I was going to say the same as above, the fuse it's piggybacked off might be protecting the wire coming into the fuse as well as the output. Reduce the rating of the original fuse by at least the same as you add on the piggyback so the new total is lower.
If it's inside the dash though could you not piggyback off the switched live for the radio? It's already protected by the fuse for the radio.
I ran new wires directly from the battery to run auxiliaries on both my vehicles. The Berlingo they just run from inline fuses connected straight to the battery +ve and then under the car to the boot compartment (if I plug a 12v fridge in the boot and leave it that's my own stupid fault). The MG they run similar through the bulkhead via a relay switched by the ignition to a 2nd fuse box under the dash which distributes to the 12v sockets, radio, etc.
Thats good. Regarding existing earth points, on my van some are 'signal' earths that are used for reference and should not be used, the heavier duty ones are power earths for stuff drawing current. Best not to put your earth on a signal earth. My van has about 5 earths in the cab, some of each type.
On that age of Sprinter, just attach the earth to steering column just below the fuse box.
I used to deal with plenty installations where earth wires had just been attached the lower fuse box mounting stud, with an additional M6 nut on top of the existing one.
