EHU stands for “Electric Hook-Up” on a motorhome – a mains electricity connection at campsites that powers your onboard appliances and charges your leisure battery. Unlike your home electricity supply, EHU typically provides limited amperage (between 6A and 16A depending on the site), which means you cannot run all your appliances simultaneously without tripping the circuit breaker.
The Cold Reality: When Your Hook-Up Goes Dead
Picture this: you’ve just arrived at a campsite in the Lake District after dark in November. It’s 4°C outside, drizzling, and you’re looking forward to warming up your motorhome. You unroll your orange Arctic cable, plug into the bollard, connect to your van, and switch on both your heating and kettle to get comfortable quickly. Suddenly, everything goes dead.
The bollard has tripped. You’re now fumbling in the dark with a torch, trying to locate the reset switch on an unfamiliar electrical post while other campers peer out their windows. Your van is getting colder by the minute, and you have absolutely no idea what you did wrong or which appliance caused the problem.
This scenario happens to thousands of first-time motorhomers every winter, and it stems from a fundamental misunderstanding of what does ehu mean motorhome-wise. The assumption is simple and wrong: that an electric hook-up gives you the same unlimited power you have at home.
What EHU Actually Means (And Why It’s Not Like Home)
EHU is motorhome jargon for Electric Hook-Up – a standardised mains electricity connection available at most established campsites. It allows you to plug your motorhome into the site’s electrical supply to run appliances, charge batteries, and power heating without draining your leisure battery or running a generator.
The critical detail that catches people out: amperage limits. At home in the UK, your domestic circuits typically run at 32A or more. Most Caravan and Motorhome Club sites provide 16A hook-ups as standard, which sounds reasonable until you realize what that actually means in practice. Many European sites – particularly municipal aires and smaller campsites – only provide 6A or 10A connections.
This isn’t about watts directly; it’s about amperage draw. In the UK, with 230V supply, a 16A connection gives you roughly 3,680 watts total capacity. A 6A connection on a European site? Just 1,380 watts. Your kettle alone typically draws 2,000-3,000 watts.
Reality Check: When experienced motorhomers talk about “the morning kettle trip,” they’re referring to the 8am phenomenon at busy sites when everyone simultaneously switches on their kettle, hair dryer, or toaster, and bollard breakers start popping across the campground like dominoes. The warden’s morning walk typically involves resetting a dozen tripped connections.
Understanding motorhome terminology like EHU becomes essential once you move beyond basic summer camping. The hook-up cable itself is also specialised – those bright orange cables you see aren’t just for visibility. They’re cold-weather rated Arctic cable designed to remain flexible in freezing temperatures, unlike standard household extension leads which become brittle and dangerous.
The EHU Connection System
A proper motorhome EHU setup consists of several components:
- The bollard/post: The site’s electrical distribution point with a circuit breaker and weatherproof socket
- Your hook-up cable: Typically 25m of 2.5mm² Arctic-rated cable with waterproof connectors (available from retailers like Screwfix for £40-80)
- Your motorhome inlet: Usually mounted on the side of your van with a weatherproof cover
- RCD protection: Residual Current Device that cuts power if it detects a fault (legally required)
- Consumer unit: Your motorhome’s internal distribution board with individual circuit breakers
UK sites generally use blue 3-pin industrial connectors (BS EN 60309-2), while Continental European sites use the same CEE17 blue connectors. You’ll occasionally encounter older sites with different systems requiring adaptors.
How to Use EHU Without Tripping Out
Here’s the proper procedure, developed through practical experience (and repeated failures):
Step 1: Check the Amperage Before You Plug In
Look at the bollard or ask at reception. Is it 6A, 10A, or 16A? This determines everything. Calculate your available watts: amps × 230V = total watts available.
Step 2: Fully Unwind Your Cable
This is non-negotiable. A coiled cable drum carrying high current generates heat through induction. The cable can overheat inside the coil, melting insulation even while the outside feels cool. This destroys £50-80 cables and creates a fire risk. Fully unwound cables dissipate heat safely.
Step 3: Connect in the Correct Sequence
Always connect bollard-end first (while switched off at the bollard if possible), then connect to your motorhome inlet, then switch on the bollard, then finally switch on your motorhome consumer unit. This sequence prevents arcing and protects both your equipment and the site’s supply.
Step 4: Know Your Appliance Draw
Learn the amperage of your major appliances (divide watts by 230 to get amps):
- Kettle: 8-13A (2,000-3,000W)
- Microwave: 4-6A (900-1,400W)
- Hair dryer: 4-8A (1,000-2,000W)
- Air conditioning: 5-8A (1,200-1,800W)
- Battery charger: 2-5A (500-1,200W)
- Diesel/gas heating: 1-3A (200-600W)
- Fridge (on electric): 1-2A (150-300W)
- LED lighting: 0.5A total (100W)
Step 5: Prioritize and Sequence Your Usage
On a 16A supply, you can run your heating, fridge, lights, and charger simultaneously with some margin. Add a kettle and you’re at the limit. On a 6A European supply, it’s kettle or everything else.
The practical approach: heat water in your kettle, then switch it off before using the microwave. Run the hair dryer while the kettle’s cold. Think sequentially, not simultaneously.
Step 6: When You Trip the Supply
Switch off appliances in your motorhome first, then go to the bollard and reset the breaker. If it trips immediately when you reset it, you have a fault – disconnect and investigate. If it holds, you simply overloaded the circuit. Reduce your load and try again.
Many Camping and Caravanning Club sites have wardens who will help if you’re struggling, but repeated tripping suggests you need to fundamentally change how you’re using power rather than just keep resetting.
Reality Check: Some experienced motorhomers carry a plug-in ammeter (£15-25) that displays real-time amperage draw. When you’re learning, this removes all guesswork – you can literally watch the numbers and see that switching on the kettle adds 10A instantly.
What Goes Wrong When You Get EHU Wrong
The consequences of EHU misuse aren’t trivial:
Immediate site issues: Repeatedly tripping your bollard may result in site wardens disconnecting your supply or, in extreme cases, asking you to leave. You’ve paid for your pitch, but you’re also disrupting site infrastructure.
Cable damage: Running a partially-coiled cable drum under high load melts the cable insulation from the inside out. Replacement Arctic-rated cables cost £50-80, and a damaged cable is dangerous to use.
Safety risks: Using household extension leads instead of proper motorhome Arctic cable, or running cables without RCD protection, creates electrocution risks, especially in wet conditions. People have died from electrical faults in caravans and motorhomes.
Bollard damage: Incorrect connection procedures or faulty equipment can damage site bollards. Some sites charge £200-500 for bollard repairs if you’re found responsible.
Winter comfort and damage: Without understanding how to use EHU effectively in winter, you can’t run heating reliably. This isn’t just uncomfortable – prolonged cold can freeze your water system, causing pipe splits and pump damage costing £300-1,000+ to repair professionally.
Perhaps most frustrating: running out of gas and having no heating backup because you never learned to use the electric supply properly. Understanding motorhome-specific terminology and systems prevents these expensive learning experiences.
Beyond the Basics: EHU Refinements
Once you’ve mastered the fundamentals, experienced motorhomers develop sophisticated approaches:
Inverter awareness: Counterintuitively, a good 2,000W inverter running off your leisure battery can sometimes provide more peak power than a 6A EHU (1,380W). Some motorhomers use EHU just for battery charging and low-draw appliances, then run high-draw items briefly from the inverter.
Load management systems: Higher-end motorhomes have automatic systems that shed loads when approaching amperage limits, preventing nuisance tripping.
Dual cable strategy: Carrying both a 25m cable for distant bollards and a lighter 10m cable for convenient pitches saves dragging unnecessary cable.
Continental adaptors: While UK and European sites largely use the same CEE17 blue connectors, some Mediterranean and Eastern European sites use different systems. A basic adaptor set costs £20-30 and prevents connection problems abroad.
Frequently Asked Questions
Can I use a normal extension lead for motorhome hook-up?
No, absolutely not. Household extension leads are not rated for outdoor use, are not weather-sealed, lack the correct connectors, and aren’t designed for the continuous high-current draw that motorhome appliances demand. They pose serious safety risks including electrocution and fire. Always use proper Arctic-rated motorhome hook-up cable with weatherproof connectors.
What happens if I plug into EHU without an RCD?
RCD (Residual Current Device) protection is legally required and detects electrical faults that could cause electrocution. Most modern motorhomes have built-in RCDs in their consumer units. If your older motorhome doesn’t, you must use an RCD adaptor plug (available for £15-30 from Screwfix or caravan dealers) between your cable and the bollard. Some sites won’t allow connection without visible RCD protection.
Do I need EHU or can I rely on my leisure battery?
It depends on your usage and season. In summer, with LED lighting, a modern fridge, and solar panels, you can often wild camp for days without EHU. In winter, running diesel heating drains batteries quickly, and limited daylight reduces solar charging. Most motorhomers use a mix: EHU on sites for convenience and unlimited power, battery power when wild camping or on aires. EHU also runs air conditioning, which batteries cannot sustain for long.
Why does my trip switch keep flipping even though I’m only running the heating?
First, check whether it’s the site bollard tripping or your internal consumer unit – they’re different issues. If it’s the bollard, you may have a faulty appliance or water ingress causing an earth fault. If it’s your internal RCD, same diagnosis. If it’s a specific appliance circuit breaker, that appliance is either faulty or drawing more current than expected. If everything trips only when you add one more appliance, you’re simply exceeding the site’s amperage limit. Also verify your cable is fully unwound, a coiled cable can trip thermal protection.
