Installing 12v Accessory Panel

Submitted: Saturday, Oct 07, 2023 at 18:25
ThreadID: 146360 Views:2308 Replies:5 FollowUps:5
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I want to install a 12v accessory panel in my caravan. I have included a picture of the wiring in my van which has three free terminals. What I’m really unsure of is where to connect the two earth wires. I’ll install a switch to isolate the panel as well. Any ideas of the best way to do this?

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Reply By: IvanTheTerrible - Saturday, Oct 07, 2023 at 20:26

Saturday, Oct 07, 2023 at 20:26
That is a fuse panel. There is no earth in that fuse panel. Doesn't look standard either
AnswerID: 644572

Reply By: RMD - Saturday, Oct 07, 2023 at 20:32

Saturday, Oct 07, 2023 at 20:32
Sporto
Do you know what the two orange wires connect to in that box and elsewhere? ie, the other ends of them.
Seeing they are similar gauge to the Red FEED wire, they may be earth wiring. Hard to tell, but if 12v is present at the red and a multimeter test to the orange wires. might reveal they are negative side of the battery. It is strange the orange ones seem to have a fuse between them.
Can you test them to confirm their polarity?
The devices/system running off the current fuse panel appear to have/likely to have, their negative connections at or near the units they feed. You may know that already!
For general accessories, the additional outlets will be handy but really not suited to running a fridge, IF that is what you intend.
Pull that yellow fuse out and see if one OR both sides of that fuse link is negative side of battery.
AnswerID: 644574

Follow Up By: IvanTheTerrible - Saturday, Oct 07, 2023 at 21:43

Saturday, Oct 07, 2023 at 21:43
"Pull that yellow fuse out and see if one OR both sides of that fuse link is negative side of battery."
There is a high probability the he will see the earth through whatever that fuse is powering. YOU CANT USE THAT EARTH!
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FollowupID: 924714

Reply By: IvanTheTerrible - Saturday, Oct 07, 2023 at 21:47

Saturday, Oct 07, 2023 at 21:47
As a professional I'm 100% positive that there are no negative wires in the picture.
AnswerID: 644575

Follow Up By: Member - silkwood - Sunday, Oct 08, 2023 at 11:33

Sunday, Oct 08, 2023 at 11:33
Despite having red wiring going to the upper contact (probably used the wrong colour?) that fuse box generally has the earth at the top (the centre upper contact). I've had a couple like that, where it does not use a bus bar style connection.

Could that be the issue?

Cheers,

Mark
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FollowupID: 924716

Follow Up By: Kazza055 - Sunday, Oct 08, 2023 at 12:22

Sunday, Oct 08, 2023 at 12:22
No silkworm, it is the same as in my van and there is no earth in that fuse block. I was going to add a circuit but could not get an earth. I assume they are joined in the the wall cavity behind the block.

I think Jaycar sell that fuse block.
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FollowupID: 924720

Follow Up By: Allan B (Sunshine Coast) - Sunday, Oct 08, 2023 at 13:10

Sunday, Oct 08, 2023 at 13:10
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Silkwood… No. It is not the issue. That upper central stud connection is the positive feed to the fuse block correctly coloured red.
Cheers
Allan

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FollowupID: 924721

Reply By: Allan B (Sunshine Coast) - Saturday, Oct 07, 2023 at 23:39

Saturday, Oct 07, 2023 at 23:39
.
That extra fuse in the box is rated 20A (yellow body) and is a circuit unconnected to the main 12v system wiring. It is likely to be a separate feed from the tow vehicle to a 3-way fridge. In any case, it surely is not a negative circuit and therefore has no part in the search to connect the negative for the new accessory panel.

Sporto, you need to locate where the negatives associated with those visible positives are. Most likely they are all terminated to a bus or stud close to the van battery. (I assume the van does have a battery) As the visible positives are mostly red I would assume that the associated negatives will be black or maybe white. You will just have to search for them. Connect your accessory panel negatives to that same point.
Cheers
Allan

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AnswerID: 644576

Reply By: Sporto - Sunday, Oct 08, 2023 at 16:48

Sunday, Oct 08, 2023 at 16:48
Thanks everyone for the responses, it would appear that there isn’t a negative here. The orange cable is as someone suggested a fuse for the cable to the fridge.

There’s another cable that I can use for the panel which has a positive and a negative. I’m pretty sure it’s attached to the above fuse panel, so I shouldn’t need to add another fuse. I’ll check this and remove the fuse as I install the panel.
AnswerID: 644583

Follow Up By: Allan B (Sunshine Coast) - Sunday, Oct 08, 2023 at 17:13

Sunday, Oct 08, 2023 at 17:13
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Sporto, that's good news. As all the negatives in your van are commoned together, it is OK to pick up a negative source from any one of them…. provided that the cable you choose is capable of carrying the additional current load, which would be pretty small in your case.
However, the cable that you are running to your new panel should be large enough to suit the existing fuse.
Cheers
Allan

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