wiring up 12s towbar socket

[redjeff1980]

Hi guys,

I've bought a pre wired 12 s socket and whilst reading through the fitting instructions I have noticed it contradicts itself. In the written section it states that 2 wires should be taken from the live battery terminal to a fuse, then connected to the 2 12v live sockets on the relay. However if that was how they wanted me to do it, they have only supplied 1 fuse and not enough cable.
So then the contradiction comes with the supplied diagram. The diagram shows only 1 wire from the positive battery terminal which goes to a fuse, but then splits into 2 wires which fit into the 2 12v live relay sockets. Again if this is how they wanted me to fit it, there are only 2 connections to the fuse...1 in and 1 out. Should there not be 3 connections? Maybe it is ok to use a scotch connector to split into 2?

On their website there is a suggestion that the 2nd 12v live on the relay is for a fridge over 30v, so do I even need this socket and just have the one live feed?

Much appreciate any advice.
We have a 2004 freelander and 2004 bailey pageant

 

[Jules_ht]

Is this PF Jones & the universal kit by any chance? I had exactly the same thing and rang and asked them.

Just wire the one lead into the leftmost of the two ports on the relay and it'll work fine (despite the note in the troubleshooting section of the installation notes that will blame it not working on the fact there is only one wire)!

'55 Saab 9-3 & 2005 Bailey Pageant, & I can confirm it does work fine.

 

[redjeff1980]

Jules your a star!
Your absolutely right it is the pj Jones kit, how funny is that that you had fitted the same kit. Well that's brilliant news that I can be assured it works, why they mentioned that other wire I don't know.
Do you find it charges the battery adequately enough? I was slightly concerned the battery wire was a bit thin

 

[Jaydug]

Do you find it charges the battery adequately enough? I was slightly concerned the battery wire was a bit thin

It's the fridge wire that you need to be concerned about. Have it too thin and your fridge performance when towing will be disappointing. Ideally you need two cables from the battery to the relays of at least 17amps.

 

[redjeff1980]

Thanks jaydug,

So this isn't as straight forward as it seems then as your saying 2 wires from the battery.

Can you understand from my question how this company would expect me to wire up this socket? I can't work out why the instructions contradicts itself?
Would you run 2 wires directly from the battery into 2 separate fuses and then into each 12v relay socket? If so why do you think they have only supplied 1 fuse and only enough wire length for 1 live?

Confusing or what!

 

[chrisbee1]

Thanks jaydug,

So this isn't as straight forward as it seems then as your saying 2 wires from the battery.

Can you understand from my question how this company would expect me to wire up this socket? I can't work out why the instructions contradicts itself?
Would you run 2 wires directly from the battery into 2 separate fuses and then into each 12v relay socket? If so why do you think they have only supplied 1 fuse and only enough wire length for 1 live?

Confusing or what!

I would.

 

[redjeff1980]

Ah ok well there's no harm in doing it as I'd be fitting 1 cable anyway.
Am I right in thinking each wire should be 17 amp with a 25amp in line fuse?

 

[WoodlandsCamper]

Ah ok well there's no harm in doing it as I'd be fitting 1 cable anyway.
Am I right in thinking each wire should be 17 amp with a 25amp in line fuse?

If both 17 amp wires go into the same 25 amp fuse, then OK, but you can't protect a single 17 amp cable with a single 25 amp fuse as under a fault condition the cable could catch fire before the fuse blew.

 

[redjeff1980]

Oh ok so what your saying is that the total ampage of the wire needs to be more than the ampage of the fuse? This is quite confusing then as the cable supplied with this kit is no more than 17 amp, but they have supplied a 25 amp in line fuse?

 

[WoodlandsCamper]

The whole idea of a fuse is to be the weakest point in the circuit under fault conditions. It is there as a safety device to protect any appliance in the circuit and all interconnections, therefore the fuse has to be the first item to rupture and therefore the lowest of all the current ratings.

Edit: That's why in your original posting you quote:
"In the written section it states that 2 wires should be taken from the live battery terminal to a fuse,"

ie 2x 17 amp wires (total 34 amp) safely carry a fault current of 25 amp which will blow the fuse first. The "written words" are correct.

 

[Dustydog]

http://www.towitall.co.uk/faq/1.aspx
I suggest you also do the above mod.I've done it for years and never had a problem . Remember, the earth return is as important as the love feed.

 

[Jaydug]

So this isn't as straight forward as it seems then as your saying 2 wires from the battery.!

I didn't use a kit. I bought the relays, the fuses and the sockets separately and I already had the reel of cable. I cut the two cables to length and enclosed them in heat shrink then connected them to the battery. I inserted the two fuses at a point where they would be convenient, but they need to be reasonably close to the battery. One picture shows the battery connection; the other the fuses.

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[redjeff1980]

Yes no problem doing modifications, it's just so confusing when they only send you certain parts.

There is only enough wire for 1 feed from the battery and the fuse is too high an ampage for that wire...just doesn't make sense

 

[WoodlandsCamper]

Remember, the earth return is as important as the love feed.

Now now DD, what an apt typo. hmy:

 

[redjeff1980]

#love feed# How unfortunate ha

Jaydug: now that looks a bit more substantial, much more like the sort of wiring I was expecting in this kit. So what ampage are your wires and fuses?

 

[Dustydog]

Remember, the earth return is as important as the love feed.

Now now DD, what an apt typo. hmy:

My Is and Os are too Close

 

[redjeff1980]

#love feed# How unfortunate ha

Jaydug: now that looks a bit more substantial, much more like the sort of wiring I was expecting in this kit. So what ampage are your wires and fuses?

 

[Jaydug]

#love feed# How unfortunate ha

So what ampage are your wires and fuses?

The two cables are rated at 17amps each and as far as I remember the fuses are 15amp.

 

[WoodlandsCamper]

The two cables are rated at 17amps each and as far as I remember the fuses are 25amp.

So the wires could burn out before the fuse blows? hmy:

 

[Jaydug]

I'll correct my previous typo... hmy: The two cables are rated at 17amps each and as far as I remember the fuses are 15amp

 

[Jules_ht]

I know what you mean about the thin wire supplied. I was expecting something really beefy like you get with stereo installs. But then I compared it to the wires in the post-relay section (i.e. into the back of the plug) and the van side of the wiring (via a convenient "observation point" created by the previous owner not keeping the cables taught enough whilst driving- now fixed) and decided it was beefier than them. I also considered the thickness of regular mains cable which is not that great when you strip the cores out (and 20A wire from maplin which only has a 2.3mm2 CSA).

I must confess though I did not read/notice the rating of the cable when I installed though.

Nb. the user manual for my van does say the fridge is rubbish on 12V (actually, what it says is that it's only up to the job of maintaining an already low temperature, reached by mains or gas, not for cooling the fridge).

 

[WoodlandsCamper]

I'll correct my previous typo... hmy: The two cables are rated at 17amps each and as far as I remember the fuses are 15amp

That sounds much safer.

 

[redjeff1980]

Well my dad has found out that the caravan fridge only uses 9.6 amps so that now does make sense why there is only 1 live. I doubt it would be necessary to add an extra live.

Jules: I have looked at the wire and there are no markings on it, so I will measure it later and find out. If it is less than 25 amp I'll let you know so you can fit a smaller rated fuse.

 

[Jaydug]

If you use a single cable it has to deliver for both fridge power and battery charging and also a bit of voltage drop because of the length of cable.