What Size 12v Cable?

Phippy

Phippy

New Member
Happy new year all!

I have a question regarding wiring which I hope someone can answer; I’d like to run a cable under the floor from the 12v leisure battery on one side to a kind of electrical hub/switch box(?) on the other side.

The idea being I can wire any appliances (water pump for example) on that side of the van to that box and appliances on the battery side I’ll just wire them to the battery (via fuse boxes). This means I won’t have any cables crossing the van which could get in the way as I have a pop top installed i can’t run them across the roof.

Is there a standard size cable I should use, I’ve read online I need a flexible three core mains cable but have no idea on what size?

Also does anyone know of anyone in the Southampton/Winchester/Salisbury area who does electrical work?

The floor is going down this weekend so I’d like to lay the cable down ready for when I find someone to install the rest of the system.

Thanks in advance!!
Louis
 
A water pump takes pulses of heavy current which will be seen as a voltage drop
by anything else on your 'hub' such as lights will dim and flicker noticably when the pump runs.
The pump really ought to be wired directly to the battery terminal, via a suitable dedicated fuse.
If you really do want to extend the battery feed then use a heavy cable rated well in
excess of the total current required - 3-core mains cable is not at all suitable! :)
The feed will need to be fused at the battery, but use a heavy fuse to minimise the resistance, or
you're back to flickering lights again - fuses introduce resistance (a zero resistance fuse
would never blow!) and you need to keep the extension to your 'hub' as low resistance as possible to minimise the voltage drop.
Cheers
Phil
 
Last edited by a moderator:
Thanks Phil!
Appreciate your points above, I would have run the lights off the main battery and then just the water pump and maybe a few USB charging points off the hub.

However, I’ve just spoken with Jason at Absolute and it sounds like I was trying to make it way more complicated than it needed to be!!!
 
USB's will be fine on the hub as the regulated 5v is way below any voltage drop from 12v...
in effect you have 7v of 'headroom' :thumbsup:
In general, small, steady volt drops you can live with - but a pump is heavily pulsed.
 
Last edited by a moderator:
As has been said a fuse is essential to protect the cable. The fuse needs to be as close as possible to the battery and without knowing what load you could be drawing it's hard to say what cable size you might need. However to cover all eventualities I would probably go for a 40amp fuse and 16 mm cable. You can de-rate the fuse easily but once your floor is down changing the cable would be difficult so I would go large. 16mm min. Hope that helps.
 
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5 amp cable is not really big enough
Potentially the usb socket can draw upto about 2 ish amps and the socket around 15 so i would go for a 15 or 20 amp circuit to supply it
 
I've got the Amps vs cable size listed below:

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Paulys 15A feed above would be the 1.0mm up, so maybe the 1.5mm or 2.0mm?

Single cable 1.5mm² - Car Electrical Wire, Set of 2 Colours (Red/Black) at 5m - https://amzn.to/2MnDhx4

Single cable 2.5mm² - Car Electrical Wire, Set of 2 Colours (Red/Black) at 5m - https://amzn.to/2MnhDIZ

**********************************************************************************


more info here > Installing 12v Socket /s - How Its Done -




**************************************************

ELECTRICAL CABLE:

Conductor Cross Section(mm²) – Rough Guide


0.5mm - 11Amps,

0.75mm - 14A

1.0mm - 16.5A

1.5mm - 21A

2.0mm - 25A

2.5mm - 28A

3.0mm – 33A

4.0mm – 39A

6.0mm – 50A

8.5mm – 63A
10mm - 70A


16mm - 110A

25mm - 170A

35mm - 240A

50mm – 345A

70mm – 485A

95mm – 500A



12ft/3.6m Car Extension Cable, 15A Fused, Male to Female Socket Plug Lead for 12V Vehicle Power - https://amzn.to/33PopgM

Twin cable (Flat 2 Core 1.5mm² 21Amps, 5 Metres) 5Metre - https://amzn.to/35V5nY4

Twin cable (Flat 2 Core 2.0mm² 25Amps, 5 Metres) - https://amzn.to/393hDYp

Twin cable (Flat 2 Core 3.0mm² 33Amps, 5 Metres) - https://amzn.to/377qV41

Round Twin 2 Core Cable 12v 24v Thin Wall Wire (25 AMP Rated 2mm²) 10 Metre - https://amzn.to/393hGU5

Single cable 1.5mm² - Car Electrical Wire, Set of 2 Colours (Red/Black) at 5m - https://amzn.to/2MnDhx4

Single cable 2.5mm² - Car Electrical Wire, Set of 2 Colours (Red/Black) at 5m - https://amzn.to/2MnhDIZ

Single cable 6mm Red (53A) 5M 12v Automotive Cable - https://amzn.to/2RO1hLp


4 (4AWG)(25mm2)(170A) cable - https://amzn.to/374ehmm

6 (6AWG)(16mm2)(110A) cable - https://amzn.to/36YMTpy

8 (8AWG)(10mm2)Gauge Silicone Wire - https://amzn.to/39aDD3U

10 (10AWG)(6mm2) Gauge Silicone Wire - https://amzn.to/2SgPG9L

12 (12AWG)(4mm2) Gauge Silicone Wire - https://amzn.to/2rkXGeE

Power (4AWG)(25mm2)(170A) Battery Cable - https://amzn.to/2rlghXZ

Red Battery/Starter/Welding Flexible PVC Cable Wire 5 Meters 10mm 70Amp - https://amzn.to/2SobAYz

Black Battery/Starter/Welding Flexible PVC Cable Wire 5 Meters 10mm 70Amp - https://amzn.to/35Pw2W8

Red Battery/Starter/Welding Flexible PVC Cable Wire 5 Meters 16mm 110Amp - https://amzn.to/2PR0oC8

Black Battery/Starter/Welding Flexible PVC Cable Wire 5 Meters 16mm 110Amp - https://amzn.to/2rqzA2g

Red Battery/Starter/Welding Flexible PVC Cable Wire 5 Meters 25mm 170Amp - https://amzn.to/2EZ1jud

Black Battery/Starter/Welding Flexible PVC Cable Wire 5 Meters 25mm 170Amp - https://amzn.to/2EORCOQ

Red Battery/Starter/Welding Flexible PVC Cable Wire 2 Meters 35mm 240Amp https://amzn.to/2Sl0rHT

Black Battery/Starter/Welding Flexible PVC Cable Wire 2 Meters 35mm 240Amp - https://amzn.to/2EJdDyu

ELECTRICAL FUSES & CONECTORS:


10Pcs Battery Connector 600V 50A 50Amp Battery Quick Connection Plug Connector (Anderson) - https://amzn.to/35R4ijP

Midi Fuse Holder For Striplink & Midi Fuses Fuseholder Fits All - https://amzn.to/2EJntQX

MIDI High current fuse Bolt-on fuses: 100 amp blue, 5 pcs - https://amzn.to/34SD5fk

60pcs Bolt Hole Tinned Copper Terminals Set-Wire Terminals Connector - https://amzn.to/2sSFoC7

38pcs 7 Types Heavy Duty Copper Ring Terminal Connectors Assortment Kit - https://amzn.to/2rnQRJt

Master Switch Battery 12V/24V - Battery Cut Off Switch - Master Battery Isolator Disconnect Switch - https://amzn.to/34QWaPc

12 Way Blade Fuse Box with LED Indicator for Car Boat Van - https://amzn.to/34P1p1Y

6 Way Blade Fuse Box with LED Indicator for Car Boat Van - https://amzn.to/2sSFCcr

12 Way Blade Fuse Box/Bus Bar With Cover - https://amzn.to/2MmWtec

5 Gang Toggle Switch Panel, Dual USB Socket Charger 12V Power Outlet LED Voltmeter -
https://amzn.to/35MsHqV

TESA Wiring Harness Tape Heat-resistant Adhesive Cloth Fabric Tape Cable Looms - https://amzn.to/2voSk3X

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> Kit List And Stuff -- How I Done It & What I Use --



.....
 
Don't forget to factor in the length of the cable. For longer runs you will need to up the CSA. Up to 2 metres 1 mm will be fine. Up to 5 metres and you will need the 2 mm. However, to do it properly I recommend two seperate circuits. A 5 amp one for the USB and meter and a 10 amp one for the Socket.
 
travelvolts said:
Don't forget to factor in the length of the cable. For longer runs you will need to up the CSA. Up to 2 metres 1 mm will be fine. Up to 5 metres and you will need the 2 mm. However, to do it properly I recommend two seperate circuits. A 5 amp one for the USB and meter and a 10 amp one for the Socket.
Click to expand...

Ok thanks. Yeah each item on it has got its own pos and neg connection so i will do it individually like you have said.
 
Sorry it's an easy question to answer.... I want to get cig lighter in the back for a fan for the dog cage / What AWG cable do I need to get a feed there from the fuse box? Is it better for something beefier and then stick a fuse box in the back? any help much appreciated... I also need to get some 12v to under the passenger seat for an air purifier.. How do you lift the rubber flooring? thankyou..
 
How long will the wire be and what power is the fan / what current will the wire need to carry?
 
Thankyou... I'll have a look at the above... Just realising I may as well run a few lengths of speaker cable at the same time!
 
Hi,
What would be the best size cable for wiring in LED lighting and switches, sorry if it sounds a stupid question just wanted to make sure I got the right size.

Thanks
 
Interior LED lighting takes very little current. 1mm twin core confined in insulation ( as behind panels etc) is okay for 11A and would carry a load of 132W which is a lot of LED`s !! What size have you got?
 
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