Note: this blog post is based on a forum thread the original thread is here

Most electric hook ups (EHU) are protected by a 16Amp MCB (Miniature circuit breaker). So you can take 15Amp without it tripping. Without going to far into Ohms law, below is a few useful conversions (this is at 230v, but use it as rule of thumb for all campsites).

• 100Watts = 0.43Amps
• 500Watts = 2.17Amps
• 1000Watts = 4.34Amps
• 3000Watts = 13.04Amps

From the list above you can soon see that its OK to actually boil an electric kettle, even a fast boil 3kw one. Though I would not do that as you have to allow for your length of cable and volt drop and the kettle drawing more power to compensate for volt drop, but that's getting too technical.

I take a 750W microwave on camps where I have an electric hook-up = 3.2A
I also take a smaller electric kettle, about 2000w (or 2Kw if you prefer) = 8.6A
I have a small cooler running, about 100w = 0.43A
I also have 2x 11w lights running = 0.09A

Total load = 12.32A, so I don't even use my full 15Amps available. This all said, I don't run the micro and kettle at the same time, just as a precaution.

It pays to check you have a 15A supply, some sites might only give you a 6A MCB to prevent you plugging in heaters etc. Even with the 6A a 750w microwave is fine.

Look on the MCB where you plug your hook-up into and you should see it says something like B6 or B16 or C or D before the number, ignore the letter, its the number that matters.

This picture shows a typical MCB, the part that you are interested in is the bit that says B6, from this we can decide that its a Type B and is rated at 6A, so if we try and demand more than 6A it will trip. The type B is of no interest to you, but if your interested, put simple it deals with starting loads. A welder for instance would have a type D MCB fitted to prevent that initial draw on power from tripping it.

Now, more importantly all equipment used outside should be protected by a 30mA RCD (30 Milli Amp Residual Current Device). The latest IEE wiring regulations have taken this even a step further and now demand that all cables with no mechanical protection (armoured cable) are protected by a 30mA RCD, which shows how much safety is put into RCD's. All electric hook ups on a camp site should offer protection by a 30mA RCD

This is what you should be looking for, notice the test switch. Don't assume that because you have something that looks like this with a test switch, you are safe. RCD's come in other sizes to 100mA, 300mA etc and only 30mA is considered good for protection of life (something to do with the heart and how much shock it can take). So make sure you find 30mA written on the front of the RCD.

You would expect to find the RCD and MCB side by side under a flap that you can lift on your electric hook-up post. Its worth pressing the test button to make sure the RCD you expect to protect you is working, however it might be protecting all the points plugged into the hook-up so make sure you wont upset anybody by turning their power off.

So we know what to look for at our hook-up, we know what load we can take from the post safely, but do we know how to take it safely.

What you should normally find on a hook-up-post is a 15A 3pin Commando socket, and you require a 15A 3pin commando plug to connect to this.

A typical hook-up point, although I wished they all looked this well maintained.  The easiest way to purchase the plug with the correct cable and the correct sockets is to buy a proper mobile hook-up unit.

The one in the picture is a typical hook-up mobile mains unit. Fitted with a 10A MCB and protected by its own 30mA RCD, this unit is also protected to IP44 giving some degree of protection against water.

Wait, wait, wait..................lets back up a minute:

Firstly we have a 15A MCB fitted at the Hook-up, so why is the mobile mains unit got a 10A MCB fitted. Simple, its called discrimination, in the event of a fault or overload, we want the MCB most convenient to us to trip. That's the one right inside the tent, since thats fitted with a 10A MCB, this is the one that will normally blow first. Ok so we lose 5A and can only have 10A but as we proved earlier that's still a lot of juice for our needs (about 2300watts).

Also why the RCD, there's one fitted in the hook-up-point. Correct, but, when was it last tested and what if you end up at a camp site that does not have one fitted to your hook-up point. Its always best to be extra safe.

And finally what does IP44 mean, IP is a rating given to electrical items on how well they are protected against foreign bodies and water. The first figure deals with foreign bodies and the second figure deals with water. A piece of equipment that is IP44 can prevent foreign bodies bigger than 1mm entering and prevent water splashed from all directions entering.

Do consider how long you want the lead from the hook-up to your tent. The one I linked is 15M which would be no good if your nearest hook-up is 17M from your tent. Shop around there are hundreds available and with longer leads and different numbers and layouts of sockets on the the rig. Also consider that something like this needs testing at least once a year professionally and try the test button every time you go camping.

Note, you should not really be paying much to have it tested (£10 at the most is a fair figure and to be issued with a test certificate).Whilst this is not set in stone, paying more would be too much in my opinion.

You can buy cheap hook-up cables on ebay and below is a typical bad example of what you get for your money.



Take this one:

• Yellow flex generally signifies 110v use.
• The 2 gang outlet has no IP protection.
• No RCD protection means you are completely trusting the Hook-up point to have a RCD that works.
• No MCB (over current protection) means you are trusting the Hook-up point to have an MCB correctly sized and working.

The sticker in the picture shows its been PAT tested (Portable Appliance tested), in the case of this lead it just means that:

• The insulation of the cable is not breaking down and shorting the cores together.
• The earth wire is in tact and is connect at both ends.

Also the NICEIC emblem (National Inspection Council for Electric Installation Contractors) means very little here, they might be interested to see there name being used to endorse a product like this, especially if the seller isn't even in the NICEIC (Who knows)

Thought I would get a couple of close ups of the electric hook-up from my last camp



In this picture you can see a 63A/30mA RCD protecting the 3 MCB's. Each MCB is 16A (type C)



Pulling back a little and we can see there are 3 16A 3pin commando plugs, being protected by the 3 16A MCB's, however remember, the RCD is protecting all 3 circuits. This one is a good example, where you have to be on your guard. Notice the bottom left commando plug. The camp-site owners have fitted a 2way adapter and therefore if the site is busy 2 people will be running from one 16A MCB, so your limited to about 7.5A each. Nothing wrong with this, its basically a double socket, but you do have to be a little bit careful with what you use, but worse case is, it keeps tripping out because the other user is wanting the full 15A and you have to keep resetting it.

Also take care, Its often the case that you have plugged in your 25M hook-up cable and your only 10M from the Hook-up point. Don't be tempted to coil your remaining 15M up and lay on the floor next to your tent

Basically, this causes the cable to overheat and can even start melting, worse case is your tent catches fire. Try laying the cable up and down your route to the hook-up instead a couple of times.