Running multiple circuits - fuse taps / distribution blocks etc

[joe384]

I currently have a couple of fusetaps in my car, however I am going to need a few more switched ignition feeds.

What is the correct or best way of doing this? I don't really want 4 or 5 fuse taps in my fusebox, should I be looking at one of these small distribution blocks or one of these small fuse boxes?

 

[Nigel]

Depends on what you are powering.

If it is just dashcams, then a single fuse tap with a 2A fuse powering a distribution box powering the cameras is fine, just needs the one fuse, you can even miss out the distribution box and crimp two, three, four dashcam hardwire kits into a single fuse tap crimp connector, a 2A fuse is probably still enough for 4 dashcams, might need a 5A.

If you are powering multiple dashcam batteries, each wanting 8A, then you should be looking at taking power from the battery or engine compartment fusebox, and probably running individual cables for each device, with each cable individually fused close to the source of the power. A single very thick cable to a distribution box would be feasible.

 

[joe384]

I do have a dashcam battery, but that in on it's own fuse tap (and will stay that way, seperate from everything else)

The other things are just a single dashcam, igniton detection for my tracker, and a relay. So not a lot at the moment, I can probably just stick with a 2 amp fuse. What about the earth connections? I guess join them together with another crimp (rather than having 3 seperate earth connections)

 

[Nigel]

What about the earth connections?

They tend to come with ring terminals for an earth point, if they will reach then just run them all to the same earth point.

If they won't reach, then you could crimp them all into one cable, or bolt them together into one. Good electrical practice would be to extend them all so that they run separately to a proper earth point, but it will work fine with them joined.

 

[EricSan]

I did this with the wiring in my son's car. Needed to use an Add-A-Fuse to power a radar detector and two relay harnesses (one that switches the 12v utility port in the center console, the other is a time delayed relay that controls charging for his dashcam parking battery). The Add-A-Fuse wire came with a barrel crimp end, so I just twisted the three positive voltage wires together and crimped it to the Add-A-Fuse wire. For the ground connection, I took each of the three wires, twisted them together, and crimped them to a ring terminal. This connected to a ground point just below the fuse box. I think I used either a 2A or a 5A fuse. Everything works exactly as expected with no issues or surprises.

 

[Nigel]

I did this with the wiring in my son's car. Needed to use an Add-A-Fuse to power a radar detector and two relay harnesses (one that switches the 12v utility port in the center console, the other is a time delayed relay that controls charging for his dashcam parking battery). The Add-A-Fuse wire came with a barrel crimp end, so I just twisted the three positive voltage wires together and crimped it to the Add-A-Fuse wire. For the ground connection, I took each of the three wires, twisted them together, and crimped them to a ring terminal. This connected to a ground point just below the fuse box. I think I used either a 2A or a 5A fuse. Everything works exactly as expected with no issues or surprises.

That is all done correctly, crimping the multiple ground wires to a single ring terminal is good.

Note that the fuse taps crimp connector and ground ring terminal crimp should be the correct size for the cable or combined cables being crimped into it, if it is significantly the wrong size then replace it, they don't crimp nicely if the wrong size. Fuse taps tend to come with crimp connectors for 10A or 20A cable, while hardwire kits tend to come with 2A or 5A cable, so the crimp connectors will work best with 4 hardwire kits crimped into their single crimp connector, they are oversized for a single hardwire kit with really thin wires. There is no need to twist the wire strands together before inserting them into the crimp, preferable not to, and not to put finger prints on the clean copper strands, since that will corrode them over time.

 

[EricSan]

Good points about matching wire gauges and finger prints while twisting. My goal for twisting was merely to keep the wire ends aligned before I managed to crimp them. It would be a bummer to have one of them slip and miss with the crimp. The add-a-fuse is 16g wire and by the time I had three wires in my hand, I was there.

 

[Nigel]

and by the time I had three wires in my hand, I was there.

Yes, I understand!

Tie-wrap the three wires together, align the ends before the tie-wrap is too tight, then hold them with a clamp, then use your hands to mount the crimp onto the wires.

 

[EricSan]

Yep, have a few off-brand pairs of these that I picked up long ago. Awesome for holding things together while soldering or crimping. The self-closure mechanism is the key.

While we're on the topic of crimping, here is a great video that illustrates the right and wrong ways to crimp wires:

 

[joe384]

Ah excellent, thanks for all your help. I already know about the various crimp sizes etc, I think I was a little worried crimping multiple cables wouldn't be as secure but it sounds like it will be fine as long as I use the correct size.

 

[Nigel]

Ah excellent, thanks for all your help. I already know about the various crimp sizes etc, I think I was a little worried crimping multiple cables wouldn't be as secure but it sounds like it will be fine as long as I use the correct size.

The only issue I know of is if you end up with too much insulation from too many wires, you might want to trim it back a bit, or just thin it with a knife, then use some heat shrink tube to cover any exposed conductors. That tends to only be an issue with high current cables though, which normally get one crimp connector each.