# wiring a parallel circuit



## billpong (Nov 10, 2009)

My electrical experience is at the circuit board level. In the automotive world, what is the best way to branch or combine in a parallel circuit (16 gauge). Some of the choices would appear to be crimping multiple wires into a single connector or a butt splice... or combining wires on a terminal strip.. or a tap connector. I also have seen piggyback connectors..
Is one of those better than the others? Or is there a good (water resistant?) terminal that makes it easy to plug or unplug additional branches in the circuit? 
Does the question make sense?

thanks!!
bill


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## Thaniel (May 25, 2008)

I'm not sure I entirely understand the question. So if I don't quite answer it I appolgize.

Weather pack connectors (usually available at autoparts stores) or similar are typically used in automotive applications. Most engine bays are designed to get wet. Here is a link to some at summit
http://www.summitracing.com/parts/SUM-900403/?rtype=10 They call them Weather Tite. 

However in an EV if the engine bay is sealed up it may not matter and standard connectors could be used.

In automotive terminal strips are rarely used. I can't think of a vehicle I've work on with one. Butt splice and crimps are pretty common. 

Personally I like to solder and heat shrink my permanat connections and then cover with wire loom for the OEM appearance. For items that must be disconnected I have typically re used connectors that I had removed from other parts that were no longer needed (or previous projects).


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## billpong (Nov 10, 2009)

Thanks Thaniel,

No terminal strips. Check.

My example here is that I have a wire that is hot when the ignition is on, and I need to run that power to the cooling fan, the potbox, a couple of relays, etc (parallel circuit).. What is the best way to branch that wire to the multiple loads? Something like a mini bus-bar or a power distributor strip widget. Does "weather pack" make something like that?


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## Thaniel (May 25, 2008)

billpong said:


> Thanks Thaniel,
> 
> No terminal strips. Check.
> 
> My example here is that I have a wire that is hot when the ignition is on, and I need to run that power to the cooling fan, the potbox, a couple of relays, etc (parallel circuit).. What is the best way to branch that wire to the multiple loads? Something like a mini bus-bar or a power distributor strip widget. Does "weather pack" make something like that?


In most cars I've worked on if the circuit is on the same fuse they just run one wire and actually branch off the wire usually with a crimp connector or soldered connection. No additional hardware. (Think "we are making milions of these things so if we can save a $1 on each one we just saved a million $". Not to say they are cheap but simple. Well maybe cheap sometimes too.)

However in BMW's I found they run individual wires to a junction box and then have more or less a "buss bar" kind of affair. Id never seen that before but maybe other german cars have it. I personally don't like the junction box scenario as it causes a lot more wire and takes up more space.


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## EV-propulsion.com (Jun 1, 2009)

There's always fuse panels like this available for 12 volt service, they work pretty good for adding different circuits, plus every fuse in in one location. Just bring a heavier wire in, (fuse that too) and up to 10 circuits out.
Mike
www.EV-propulsion.com


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## Woodsmith (Jun 5, 2008)

+1 on the fuse box.

You are effectively using one live supply to feed several items. It would be prudent to supply that feed to a fuse box and then distribute to each of the accessories via a suitable fuse link.

You can get accessory fuse boxes at any motor mart or pull one out of a scrap car at the junk yard.
It would be useful to get one that uses the same type of fuse fitting as the existing fuse box on the car so you are only carrying one type of spare fuses.


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