NBCE Wiring Tool

Pick your main parts or type the sizes, enter cable run lengths, and get cable and fuse sizes, lugs and a parts list from the NB Camping Equipment store. 12, 24 or 48V. Every suggested value can be overridden, and overrides are marked.Cable and fuse sizes, lugs and a parts list from our store, worked out from your main parts and run lengths.
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A guide, not a certified design. Check every size against the manufacturer's instructions and the rules that apply to your vehicle or boat. Any 240V work must be done by a licensed electrician. Read the full disclaimer
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Start

2. Your system 12V

Battery bank

Ah
A
W
W
A
A

3. Cable run lengths

One-way length of each run in metres, along the route the cable will take.

Wiring diagram click a part to pick a product, click a cable label to change its length or size

The Quick plan does not include wiring and fuse details: the wires and fuses are drawn, their sizes are not. Switch to the Full plan to see and choose them. Red = positive, black = negative, yellow = solar PV, thin faded red = shunt sense lead. A small hop shows a wire crossing a busbar it does not join. Product photos stand in for artwork.

Cables & fuses

RunCurrentLengthCableVolt dropProtectionConnectorsNotes

Parts list

InPartQtyStore productPrice
Estimated total of included parts
A guide, not a certified design. Read the full disclaimer

What this tool does

It sizes DC cable, fuses, breakers and lugs for the system you describe, draws the system, and lists parts we sell that match. Every figure comes from the sizes you enter and the products you pick.

What it assumes

  • Cable carries at least 1.25 × the expected continuous current, with voltage drop under 3 % over the whole run (there and back).
  • Cable resistance is calculated for copper at roughly 50 °C.
  • Current ratings come from the cable's own product listing where it states one. Where it doesn't, the tool uses a conservative built-in figure. Published ratings are for a single cable in free air at 30 °C.
  • Run lengths are the one-way lengths you type in.
  • A fuse is the next rating above 1.25 × the current, and never above the cable's own rating.

What it can't know

  • How the cable is actually installed. Bundled cable, cable in conduit, and cable through a hot engine bay or near an exhaust all carry less than the published rating.
  • Your real loads: start-up surge on motors, compressors and pumps, duty cycle, and how much runs at once.
  • Your battery's own limits: BMS continuous and peak current, charge current limit, and the fusing its maker requires.
  • Terminal and stud sizes on parts you already own, and the space inside your battery box, locker or cabinet.
  • Anything on the 240V side of an inverter, or shore power.
  • Solar panel mounting, roof penetrations, and earthing or bonding requirements.

Your responsibilities

  • Follow each manufacturer's instructions. They override anything this tool says.
  • Meet the standards and rules that apply where you are. In Australia that may include AS/NZS 3000, AS/NZS 3001.1 and 3001.2 for caravans and relocatable premises, AS/NZS 3004.2 for marine installations, and your state's rules on vehicle modifications.
  • 240V AC work must be done by a licensed electrician. That includes wiring an inverter's output into a caravan or boat circuit, and anything involving RCDs or shore power. This tool does not size or design any of it.
  • Have the finished installation checked by a qualified auto electrician or marine electrician before you rely on it.

The parts list

Quantities and lengths are a starting point, not a final order. Check lengths, terminal and stud sizes, and physical fit before you buy. Anything you mark “Customer supplied” is still counted in the sizing but left out of the total.

No warranty

We provide this tool in good faith as a guide. NB Camping Equipment does not warrant that its results suit your particular installation, and to the extent permitted by law accepts no liability for any loss or damage arising from its use. Nothing here excludes, restricts or modifies any right you have under the Australian Consumer Law.

Questions about a plan this tool produced? Contact us and we'll go through it with you.