Wiring 12V Switches

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Hi all,

I'm in the process of building a battery box for my 12v leisure battery so we have a powerpoint for the LED lighting, phone chargers etc. I was thinking of adding 5 or 6 sockets using the image below as my inspiration

80852d1495035255-wiring-12v-switches-1.jpg


I'm going to run all of the swtiches via a mini blade fuse box which has a common live connection point.

However, I'm wondering what to do with the negative wires from the switches.

In the example i'm using as a reference, all of the negative connections from the switches have been daisy chained together with just one connection to the batteries negative terminal
80853d1495035420-wiring-12v-switches-2.jpg

Whilst this is very neat, is it safe to do?

I'm assuming that doing it this way will mean that the wire you use to connect the netagive connections up needs to be of a sufficient gauge to deal with the potential current from all of the sockets...?

Cheers

hyd
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I build 12 volt stuff all the time.

Daisy chaining is fine, so long as the total current is below the ampacity of the wire. Your weak points will be the terminals. They are prone to having the wire come out, and also the connectors don't like to stay together. Boats are wired pretty much like your box, and they have their share of those problems.

I am hoping you will not be leaving the wires stuck in the tab holes that way.

Since you are using your own device, it will be easy for you to keep an eye on it. When the switches or conductors or sockets get hot, change them out.

Connectors and crimpers from Harbor Freight suck. If you are using cheap connectors, solder them and use dual wall shrink tube.
 

mpoulton

Senior Member
Location
Phoenix, AZ, USA
The negative connections to the switches only handle the current from the tiny lights inside the switches - a few tens of milliamps. Daisy-chaining those wires is totally fine, and you can use pretty much any gauge you want. The negative connections to the receptacles, however, need to handle the full load current and if you daisy-chain those the wire will need to handle the sum of the ratings of all fuses supplying the receptacles.
 

RumRunner

Senior Member
Location
SCV Ca, USA
Occupation
Retired EE
Hi all,

I'm in the process of building a battery box for my 12v leisure battery so we have a powerpoint for the LED lighting, phone chargers etc. I was thinking of adding 5 or 6 sockets using the image below as my inspiration

80852d1495035255-wiring-12v-switches-1.jpg


I'm going to run all of the swtiches via a mini blade fuse box which has a common live connection point.

However, I'm wondering what to do with the negative wires from the switches.

In the example i'm using as a reference, all of the negative connections from the switches have been daisy chained together with just one connection to the batteries negative terminal
80853d1495035420-wiring-12v-switches-2.jpg

Whilst this is very neat, is it safe to do?

I'm assuming that doing it this way will mean that the wire you use to connect the netagive connections up needs to be of a sufficient gauge to deal with the potential current from all of the sockets...?

Cheers

hyd

Since you are concerned about overloading the negative "homerun" to the battery, you can use a terminal strip (using a heavier gauge) to a distribution bus going to a group or individual toggle switch . . .or you can build your own from a plain copper bar.

I've done this on my wiring in my motorhome extensively.
 

gfrswall

Member
Location
sacramento CA
First, I would not bother with switches. They add expense, complexity, take up space and are one more component that can fail. With sockets (USB) the most reliable way to turn something off is to simply unplug it.

With or without switches I would simply tie all the negatives together. You can do that with a terminal strip, buss bar or even wire nuts.
 
Hi there,

Thanks for the suggestions.

Just to clarify, when you say tie all of the negatives together - they will need a connection to the negative on the battery as well (a connection from the terminal strip to the battery)?
 
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