Tinned Thin Wall Cable 4mm² 39A
Tinned Thin Wall Cable 4mm² 39A
Tinned thin wall single core cable, 4mm², rated 39A. Tinned copper with a reduced insulation wall, so it is smaller in diameter and easier to route than standard wall cable of the same conductor size. The bridge between instrument wiring and battery cable.
Specification
- Conductor: tinned copper to BS EN 60228, 56/0.30 stranding
- Manufactured to: ISO 6722-1:2011 Class B, 105°C
- Cross sectional area: 4mm² (nearest AWG equivalent 12)
- Current rating: 39A nominal, conditions not stated by the manufacturer
- Overall diameter: 3.5mm
- Conductor resistance: 4.71 mΩ/m at 20°C
- Colours: red and black
Typical applications
Solar array home runs on small systems, sensor and instrument feeds, lighting trunk runs.
Important: this is not solar PV cable
If you are wiring the array side of a solar installation, from the panels down to the charge controller, you need double insulated PV cable to EN 50618 (designation H1Z2Z2-K): 1.5kV DC rated, 120°C, UV and ozone resistant, with a 25 to 30 year design life. Thin wall is not that, and we will not sell it to you for that job. The run from the MPPT to the battery, on the other hand, is battery cable and thin wall is fine for it at these sizes.
Current rating: what the manufacturer actually says
AMC publish 39A for this cable as a nominal current rating, with no conditions alongside it. Their datasheet says the ratings are "provided as a guide only, and can vary depending on the application, condition and environmental factors". There is no stated ambient temperature, no installation method and no bundling basis. The same number is quoted across this market as though it were a rated ampacity, and it is not.
Treat it as a single unbundled cable in open air and derate from there: roughly × 0.7 for two or three cables bundled or in conduit, × 0.6 for four to six, × 0.5 for seven or more. Those factors are ours, following ABYC E-11 practice, not AMC's. The datasheet is linked at the foot of this page if you want to check us.
Volt drop is usually what decides the size, not current
At 12V a 3% volt drop budget is 0.36V in total, there and back. That almost always calls for a larger cable than the current rating alone would suggest. BS EN ISO 13297 permits up to 10% for general circuits and 3% for equipment vital to safety.
Work it out properly with our cable size calculator, which checks current rating and volt drop independently and hands you a configured assembly at the end.
What goes with it
- Copper tube terminals: 4mm² in M5, M6, M8
- Adhesive lined heat shrink: 9.5mm
Datasheet
Every cable specification on this page comes from the manufacturer datasheet, and you can read it yourself: download AMC thin wall single core cable (PDF). We host the file here rather than link to the manufacturer, so it stays available and stays the version our figures were taken from. The derating factors above are ours, not the manufacturer's.