 | Home > In Car Electronics > W terminal Wire Gauge? |
 
|
|
|
| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347   
|
Hi guys,
Another electrical question I'm afraid (groans all round). This time it concerns Wire Gauges - ie how thick to power what? I want to wire in a tachograph to my W terminal - I assume this will need a fairly heavy wire? Secondly I want to wire in my fusebox, I fear I may have purchased the wrong sort as it seems to be for running wires through rather than a supply and run off so I will get a Blue Sea box on order, but what gauge of wire do I need to run from the battery terminals to the fusebox. I imagine there is a set way of working the thickness required for the item but I don't know where to look. Any pointers would be gratefully appreciated. Thank you  Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197
Self confessed mileage hunter  |
||
24th Jan 2015 4:05pm |
|
| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971 
|
What sort of current do you need to put down the cable and how long is it?
As a starting point this table might be of use: http://www.engineeringtoolbox.com/wire-gauges-d_419.html Bear in mind voltage drop due to the cable resistance - there's something linked to from that page about it on a 12V system. Fuses need to go as close to the battery as far upstream as possible. The fuse is to protect the cable in case of a fault on the cable, so I personally wouldn't run a cable out of the battery box without a fuse. If the insulation rubs through on the way out of the box and contacts the body then you may get a fire if there's no fuse to blow. Slightly OT: When I'm building up controllers, I always have the cable feeding all my individual circuit breakers/fuses rated to carry the full current of the incomer, so if there's a fault somewhere the incoming fuse will blow before the cable goes. That's not to say the cable is sized for voltage drop at the full current, because under non-fault conditions you may be running at far lower currents. Not everyone operates like this and I have come across an installation with 2.5mm2 cables feeding a row of circuit breakers with no upstream protection smaller than 100A. That's fine to run the loads it was supplying but not fine if anything went wrong. |
||
|
24th Jan 2015 4:23pm |
|
| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20453
|
Audio cables gauge are measured form 0 or 00 Being the largest to 4 gauge, 8 gauge etc etc.
So the smaller the number the larger the gauge in this instance. As mentioned voltage drop across the cable length is worth bearing in mind and there are charts online to follow regarding this. I'm running a 4 gauge for my Amp which is a bit overkill for a 50A load, but the cable run is short too so it'll be running most efficiently. |
||
|
24th Jan 2015 4:36pm |
|
| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
|
Thanks for spotting that Munch90
 Indeed I meant the rev counter.
The rev counter wire is just from the back of the alternator W terminal to the back of the dial so maybe 2m? Cupboard: Thanks for that I think it will be very useful. I'm planning to put the fusebox into the battery box next to the battery with a dedicated wire from the fuse box to the battery as currently it is a little like spaghetti junction in there and I want to neaten it up and make it all a bit more safe. Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197 Self confessed mileage hunter |
||
|
24th Jan 2015 4:56pm |
|
| munch90 Member Since: 26 Oct 2013 Location: guildford Posts: 3558 
|
think your find the w terminal wire is only a signal wire really so guessing it only needs to be light gauge wire
|
||
|
24th Jan 2015 5:09pm |
|
| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
|
Would 3mm wire be sufficient? Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197
Self confessed mileage hunter |
||
|
24th Jan 2015 8:43pm |
|
| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6611 
|
0.5mm^2 would be fine, it's only carrying a tiny, tiny current.
Use the thinnest stuff you've got (within reason)   1988 90 Td5 NAS soft top
2015 D90 XS SW |
||
|
24th Jan 2015 8:45pm |
|
| JAY BOY Member Since: 04 May 2010 Location: Not here Posts: 1706 
|
3MM would be more than adequate
 |
||
|
24th Jan 2015 9:22pm |
|
| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
|
Thank you again everyone for your help will toddle down to halfords tomorrow and pick up some bits
Just need to work out how many pulses it sends now  Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197
Self confessed mileage hunter |
||
|
24th Jan 2015 9:45pm |
|
| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
|
if it's only for a signal cable I'd have popped a bit of 0.2mm^2 in an envelope and posted it to you
 |
||
|
25th Jan 2015 11:11am |
|
| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
|
Haha Your very kind Cupboard.
I needed to pop in anyway and get some car washing stuff anyway. Thanks for the offer though! Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197 Self confessed mileage hunter |
||
|
25th Jan 2015 2:41pm |
|
|
|
| All times are GMT |
< Previous Topic | Next Topic > |
Posting Rules
|
Site Copyright © 2006-2024 Futuranet Ltd & Martin Lewis
