Cable installers work with "live" wires all the time. There's no voltage on their lines that I'm aware of, only signal and maybe some interference. You do need to disconnect lines for satellite dishes or mast mounted amplifiers since they may have a power injector that adds voltage into the lines.
When crimping the new cable, make sure the center wire is long enough (you can trim it after you crimp a new end) and get some of metal mesh that forms the second wire in tight contact with the crimped fastener. I usually pull some of that mesh back over the insulation so there's a tight bond when it's crimped.
An extension cord
- is usually lighter gauge than house wiring
- introduces an additional connection, another opportunity for reduced voltage
- the connection may be exposed to dust and/or liquids
- the connection can easily be loosened exposing open, live conductors
- the connection may be in a place more accessible to children, pets, falling metallic debris, vehicle tires, etc.
The lighter gauge wire may lower the life of the fridge's motor by not providing full voltage especially during motor starting. In severe (though rare) cases, the light gauge wire could be a fire hazard if the fridge runs especially hard, like when an overabundance or lack of refrigerant oil causes the pump to work hard.
In commercial and industrial sites (at least around here), fire inspectors require immediate removal of extension cords from anything vaguely permanent looking.
If your kegerator is going to be in use for some time, why not install a real outlet in the right place for it? In a garage or utility area, the wall doesn't (usually—depending on your wife) have to be perfectly patched. The wire, outlet, box, nails, etc., won't set you back more than about $15.
Best Answer
Hazards
I believe the main issue is that they can get warm if you don't fully extend them and then draw a high current through the coiled wire.
See Leads & Extension Lead Safety
RCD (Residual-current device) or GFCI (Ground Fault Circuit Interrupter)
Most advice is to use an RCD with extension cables over 15m. I use a plug-in RCD. You can buy replacement outlets(wall-sockets) that incorporate an RCD.
I suspect this advice is simply because the length of cable increases the likelihood of accidental damage to the cable (spades, shut in doors, etc)
Voltage drop
The voltage in the UK is nominally 230 V with a tolerance of +10% to -6% (in much of the EU it is +/- 10%) - In practice most wall outlets are likely to be at 240V as this is the standard voltage prior to EU harmonisation and is within the tolerance.
This means that equipment must be able to work with voltage as low as 216.2 V.
If plugged into a 240 V wall outlet, your 50m cable would have to lose nearly 24 volts before it dropped to a level below the UK tolerance in supply.
That means, at 13A and 50m the voltage at the end of the cable would be OK so long as the cable had a resistance of less than 30 mV per amp per meter. This means you want a copper cross-sectional area of at least 1.5 mm². Ref, Table
The details for your specifc product don't mention the conductor size so you can't do the calculations for yourself.
You can check the voltage drop easily with a "kill-a-watt" type device or a suitable multimeter or voltage-tester rated at least Cat-II 600. If the drop is too high you have the statutory right (in the UK at least - SOGA 1979) to return the cable as unfit for purpose.
Generally, when voltage is low, appliances stop working or work poorly (dimly, slowly or intermittently) in most cases this wont cause a hazard.