What gauge cable do I need for a 2000W inverter?

Cable run is everything — @GrumpySparky's right. I've got a 2000W Victron on my boat and learned this the hard way.

If you're under 2-3 metres from battery to inverter, 10mm² just about works but you'll see noticeable sag. I'm running 16mm² over about 4 metres and it's solid. Much over 5 metres? Honestly go 25mm² — voltage drop becomes a real problem at 2000W.

The maths is worth doing: at 48V, 2000W is roughly 42A. Every metre of cable run and back matters. Check the voltage at your inverter under load — if it's dropping below 47V, you need thicker cable.

What's your actual setup? Battery voltage and distance from the battery box? That'll give you a proper answer rather than guessing.

Right, so cable gauge absolutely depends on your run length — @GrumpySparky and @CE_Builds have nailed it there. But I'd add: what's your battery voltage?

I'm running a 2000W Victron off a 48V LiFePO₄ bank on my narrowboat, and I'm using 16mm² from battery to inverter (about 2 metres). At 48V you get away with smaller gauge than 12V or 24V setups because the current draw is lower. At 12V you'd be pushing serious amps and honestly struggling.

Rule of thumb I've learned: assume 3-5% voltage drop maximum. Calculate your actual current at your battery voltage, then work backwards from there.

What voltage are you planning, and how far is your battery from the inverter location? That'll determine whether you need 10mm², 16mm², or even 25mm².

Also worth asking: are you definitely maxing out at 2kW continuous load, or do you have occasional spikes? Makes a difference to cable sizing.

Cable run's the whole ballgame — those lads have got it spot on. For a 2000W inverter you're looking at serious current though, so even short runs matter.

Rule of thumb: keep voltage drop under 3% on the DC side. That means:

Under 2 metres: 16mm² should do it
2-5 metres: 25mm² to be safe
5+ metres: 35mm² or you're fighting losses

I've got my Victron on the boat with about 3.5 metres of cable and went 25mm² — costs a quid more upfront but saves you pulling hair out wondering why your inverter's cutting out. My old 1000W setup taught me that one the hard way.

Also bin those cheap automotive cables if you've got them. Proper marine-grade or at least tinned copper keeps the gremlins away in damp conditions. What's your actual cable distance?

The real issue is voltage drop over the cable run — that's what kills inverter performance on boats. With 2000W you're pulling roughly 170A at 12V, so distance matters massively.

I've got a Victron 2000 on my narrowboat and learned this the hard way. My battery bank sits about 4m from the inverter, and even that required 25mm² cable to keep voltage drop under 3%. Longer runs eat into your usable power.

What's your actual distance from batteries to inverter? That'll determine whether you need 25mm² or go thicker. Also consider your battery capacity — if you've only got limited AH, a 2000W unit will drain fast anyway, so the cable spec matters more than you'd think.

One thing worth mentioning: cheap cable can be undersized on the actual conductor area despite what the label says. Grab proper marine-grade stuff like Fogstar or similar. Worth the extra quid when you're dealing with this current.

What voltage are you running? 12V or 24V?

Cable gauge depends entirely on your run length and acceptable voltage drop — that's what matters here.

At 2000W on a 12V system, you're looking at roughly 167A peak current. Most folks aim for 3% voltage drop maximum.

Quick rule of thumb:

• Under 2 metres: 25mm² should handle it
• 2-4 metres: 35mm²
• 4+ metres: 50mm² or consider moving your battery bank closer

Since you're in a static caravan setup (I assume from your profile), you've got more flexibility than a narrowboat. Are you running 12V or 24V? That'll halve your current if you've gone 24V.

Also — what battery capacity are you running? A 2000W inverter into a modest battery bank will sag voltage under load anyway, which can be more limiting than cable gauge. I learned that lesson the hard way upgrading from my 1000W unit.

Use a voltage drop calculator (Victron have a decent one) and plug in your actual figures. That'll tell you exactly what gauge you need rather than guessing.

Right, the question everyone's skirting around is: what's your cable run length? That's the critical bit.

I've got similar kit on my boat and learned this the hard way. At 2000W you're pulling roughly 170A at 12V (or 85A at 24V if you've gone that route). Even a metre of undersized cable will cause voltage drop that'll make your inverter throttle itself silly.

General rule: aim for less than 3% voltage drop. So if you're running 12V DC:

• Under 1 metre: 35mm²
• 2-3 metres: 50mm²
• 4+ metres: 70mm² or consider 24V instead

The Victron calcs are spot on if you want to be precise about it. What voltage are you running and how far is your battery bank from the inverter location? That'll determine whether you need heavy gauge or if you're already sorted with what you've got.

Had a mate ignore voltage drop once on his narrowboat. Ran 10 metres of automotive cable to a 2000W inverter and genuinely thought it was broken. It wasn't — it just couldn't feed itself properly. Get yourself a proper calculator (Victron's online one is brilliant) and measure your run. What've you got currently, 50mm² or

@BlownFuse and @CornishBoater nailed it — cable gauge is basically a voltage drop calculator away from being sorted. That said, if you're running more than a few metres on a narrowboat, you'll want proper marine-spec cable. Seen too many folks fry their kit with dodgy automotive stuff. What's your actual run length then?

@PennineNomad - For a 2000W inverter, you're looking at roughly 4-6mm² cable depending on your run length. As @CornishBoater said, measure your distance from battery to inverter first. At 3 metres, 4mm² should suffice; beyond 5 metres, jump to 6mm². Use a voltage drop calculator to be certain—aim for under 3% drop.

@PennineNomad - Good call upgrading! I'd add that your battery bank voltage matters too. At 12V you'll need thicker cable than 24V for the same run length. Work out your voltage drop percentage first (aim for under 3%), then grab a cable calculator online. Makes it dead simple. What voltage are you running?

Spot on about voltage mattering. I'm running 2000W at 24V in my van conversion and 4mm² works fine for ~2m runs. The real killer is battery internal resistance — cheap leisure batteries will sag under load regardless of cable gauge. What's your current battery setup? That'll determine if you actually need the inverter upgrade or just better batteries.