MR2 Roadster Owners Club

The Workshop => Audio / Security / Electrical => Topic started by: manchestermatt1986 on June 14, 2012, 17:29

Title: Wires?
Post by: manchestermatt1986 on June 14, 2012, 17:29
Iv recently been doing a overhaul on the car and some things need wiring up. The question i need answering is on the thickness of wires.

I have put a new illuminated button for the rear fogs and also im going to rewire my front fog lamps. The fronts are aftermarket and the car is import incase it makes a difference.

Also im going to get an amp for some after market front speakers

Does wire thickness make a diffrerence? Can they be too thin or too thick? are there different types of wires?

I can handle very basic electrics like splicing into things and fitting headunits but just wanted some more tips/knowledge
Title: Re: Wires?
Post by: Anonymous on June 14, 2012, 17:35
Wires can never be to big. Always fit larger gauge wire, otherwise it could cause a fire.
Title: Re: Wires?
Post by: mrzwei on June 14, 2012, 18:06
Basically, Watts = Volts X Amps

You know the voltage is 12 and you know the wattage of the speaker or whatever  and, from the above, Amps = Watts divided by Volts.

The thickness of the wire must be able to AT LEAST (as said) carry those Amps or it will overheat.

If you are drawing more than one speaker from a single source wire then the source wire must be thick enough to carry the total number of Amps.

Something like that   s:D :D s:D
Title: Re: Wires?
Post by: Steve Green on June 14, 2012, 20:59
Probably best to calculate Voltage at at least 13.5V as that is the charging voltage of the battery, or what the alternator shoves out.

It adds a little more safety factor.
Title: Re: Wires?
Post by: manchestermatt1986 on June 14, 2012, 22:58
So I can't go 'too big' or the wrong type
Title: Re: Wires?
Post by: Anonymous on June 14, 2012, 23:22
Depending on amp go for 10 gauge wire should be more than enough, and any wire type be fine.
Title: Re: Wires?
Post by: Steve Green on June 15, 2012, 08:20
Any type? Not really.
Most car wiring is made from multi-cored (10 or more) copper as flexibility and vibration issues are usually important. Domestic cables have far fewer cores.

Have a look at http://www.autoelectricsupplies.co.uk/category/10

If you are routing cables through bulkheads etc make sure they are further protected and secured in place.
Title: Re: Wires?
Post by: Anonymous on June 15, 2012, 09:19
Quote from: "Steve Green"Any type? Not really.
Most car wiring is made from multi-cored (10 or more) copper as flexibility and vibration issues are usually important. Domestic cables have far fewer cores.

Have a look at http://www.autoelectricsupplies.co.uk/category/10

If you are routing cables through bulkheads etc make sure they are further protected and secured in place.

very true but unless your buying twin and earth cable 99% of cables sold in b&q, halfords, etc are all flex ie multi-strand.
Title: Re: Wires?
Post by: SteveJ on June 15, 2012, 10:23
Quote from: "rbuckingham"
Quote from: "Steve Green"Any type? Not really.
Most car wiring is made from multi-cored (10 or more) copper as flexibility and vibration issues are usually important. Domestic cables have far fewer cores.

Have a look at http://www.autoelectricsupplies.co.uk/category/10

If you are routing cables through bulkheads etc make sure they are further protected and secured in place.

very true but unless your buying twin and earth cable 99% of cables sold in b&q, halfords, etc are all flex ie multi-strand.
And as noted by Steve G, they are still not flexible enough - car wiring is 10 strand plus, most of the stuff you get from B&Q et-al will be 3-7 strand.
Title: Re: Wires?
Post by: Anonymous on June 15, 2012, 11:25
Ive got a butchered engine loom here Matt. Just come and chop what you want off it.
Title: Re: Wires?
Post by: Steve Green on June 15, 2012, 17:16
As a footnote to wiring, it is very useful to follow the colour codes used elsewhere on the car. They are generally standard these days especially any ground -ve ones. It's much better than having a bunch of unidentified same coloured wires when it comes to troubleshooting two years down the line.
Title: Re: Wires?
Post by: manchestermatt1986 on June 18, 2012, 16:16
Quote from: "dick2ski"Ive got a butchered engine loom here Matt. Just come and chop what you want off it.

Thankyou, i may take you up on that   s:) :) s:)
Title: Re: Wires?
Post by: Anonymous on June 18, 2012, 19:00
There is a heap of wire in it. Take the lot if you want.
Title: Re: Wires?
Post by: stargazer30 on June 18, 2012, 22:19
For the AMP wiring just make sure you have an inline fuse within about 10cm of the battery on the positive feed.  Then as has been said the thicker the wire the better.  The fuse fitted should reflect the power of your amp, usually in the range of 20 to 40 amps.  If you buy an amp wiring kit it will have this.
Title: Re: Wires?
Post by: Steve Green on June 18, 2012, 22:24
Good advice, but... The fuse is there to protect the wiring and not the device or amp that it feeds.
So the wire must be able to carry a lot more than the amp needs as well.