100m mains extension lead ?

Alex_Blackwood said:
What no-one has mentioned is that apart from volt drop, the length of cable and resistance, may cause the safety device (RCD), at the shore connection, to become inopererative...
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According to VicS "The resistance of 1.5mm² is 11.2 ohms /1000m or 1.12 ohms /100m". The 2.5mm² cable will be less. An RCD needs 30mA to trip (or about 7k ohms), I don't think an ohm or two will make much difference.
 
Alex_Blackwood said:
What no-one has mentioned is that apart from volt drop, the length of cable and resistance, may cause the safety device (RCD), at the shore connection, to become inopererative. I would not even attempt it unless you can have it properly tested by a good competent electrician.
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Why would the RCD become inoperative ?

I use my 100m extension in the boat yard... sometimes with another 50 m one plugged in to it as well! There is an RCD on the system but I always use my own at my end as well!

BTW the resistance of 2.5mm² is approx 0.7 ohms per 100m so 1.4 ohms for live + neutral.

Therefore the volts drop will be approx 18 volts at 13 amps.
 
I have one - 1.5mm blue arctic cable from an electrical wholesaler. You're aren't supposed to use the yellow 'cos that's for 110v. Before I got an old hose reel on wheels, it was a major pain in the nether regions to unroll 'cos it got itself into a major tangle every time. With the reel it's a doddle.

If you're drawing much more than an inspection lamp's worth of current, it needs to be unrolled completely and the extra flaked randomly or it can overheat, but provided you do, while it's probably not recommended, I've run a small fan heater and a battery charger overnight without any problems. I wouldn't leave that sort of load unattended, though.

Do make sure the connections to the plugs are made properly and the terminals are tight, 'cos they cook if you don't.
 
Alex_Blackwood said:
What no-one has mentioned is that apart from volt drop, the length of cable and resistance, may cause the safety device (RCD), at the shore connection, to become inopererative. I would not even attempt it unless you can have it properly tested by a good competent electrician.
Click to expand...

Why? IIRC the RCD isn't measuring resistance, it's watching for an imbalance between live and neutral or ground.
 
If you're drawing much more than an inspection lamp's worth of current, it needs to be unrolled completely and the extra flaked randomly or it can overheat
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A slight exaggeration perhaps!
My 50m one is rated at 10amps uncoiled and 5 amps coiled. According to the label it is 1.5mm². The cable reel has a built in thermal trip ... which works ;)
 
VicS said:
Why would the RCD become inoperative ?

I use my 100m extension in the boat yard... sometimes with another 50 m one plugged in to it as well! There is an RCD on the system but I always use my own at my end as well!

BTW the resistance of 2.5mm² is approx 0.7 ohms per 100m so 1.4 ohms for live + neutral.

Therefore the volts drop will be approx 18 volts at 13 amps.
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Presumably you meant that the system has a 100 mA or time delay RCD and you always use a 30 mA RCD.
 
If you're drawing much more than an inspection lamp's worth of current, it needs to be unrolled completely
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That much cable, in a coil, also presents an interesting inductive load, which may trip a breaker when you power it up, regardless of weather it heats up or not.
 
Presumably you meant that the system has a 100 mA or time delay RCD and you always use a 30 mA RCD.
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I dont know what is fitted to the system. I might take a look some time. Mine is 30mA yes.

That much cable, in a coil, also presents an interesting inductive load, which may trip a breaker when you power it up
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Does coiled twin flex create an inductive load.
Will the inductance of a coiled lead trip a breaker ? An inductive load like a motor can but that not quite the same.
 
Quite an investment

As others have said, handling 100 m of 2.5 artic flex is no picnic. So, do the job properly and invest in some sort of mobile reel with a winding handle.

Also, fit a 30 mA RCD and 2 sockets. Ideally http://www.tlc-direct.co.uk/Main_Index/Wiring_Accessories_Menu_Index/RCD_Protected_Range/RCD_Protected_Range_5/index.html or similar (you may find some cheaper elsewhere) will give you not only RCD protection but also weather protection.

If you are drawing over say, 1 Amp, I agree the cable should be fully unwound. I once saw a partially unwound lead to which had been connected an electric heater. The plastic sheathed cable became so hot it fused together. The only way we could get it off the drum was with a hacksaw:(

Hope this helps,

Paul
 
greenalien said:
That much cable, in a coil, also presents an interesting inductive load, which may trip a breaker when you power it up, regardless of weather it heats up or not.
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Coiled extension leads WILL overheat.

One customer I visited was using a coiled up extension lead to power a washing machine and tumble dryer in an outhouse.

When I advised her as a very minimum, the lead should be uncoiled when supplying that much load, she replied "is that why they keep melting?"

Apparently they lasted only a few months before melting and blowing the fuse, and she had just been buying another and using it in the same way. She never thought to question why it was overheating or was it the right thing for the job.

No wonder so many people kill themselves or start a fire if people carry on like that.

P.S I persuaded her to let me fit an extra socket in the outhouse so the extension lead was no longer needed (that was not the original job I went there to do)
 
Reading one or two of these replies reminds me why, when buying a boat, one should always have the electrics checked professionally...
 
Boo2 said:
Hi,

Can anyone tell me where I can get a 100m mains extension lead from for use on the boat (I'm obviously 100m away from the sockets atm). I will draw around 6A (but 13A would be better really) and normal boat/caravan style ends.

Thanks,

Boo2
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I would use 4mm split into 2 bits. A 100m of the stuff will take some coiling. I use 2.5mm up to 40m and the fan heater slows down a bit when I turn on the electric kettle as well. This is on a 16 amp supply fuse in the boatyard and the same on my boat.
fitting the 4mm into the 16amp plug/socket is possible but fiddily and takes time.
 
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