Toggle switch with LED - Mains - Double Pole 4 Pin - Connection??

[RD1]

The were excellent in their field but some of them had a strange idea or power, but then they probably didn't think much of me, a dumb sparky

 

It's the have a go diy ( destroy it yourself ) home bodger that worries me. In our previous house, probably a diy'er, had wired in a spur socket in the utility room, you can tell it was a bodge job, no green / yellow sleeving on the earth, and he had crossed over the live and neutral. How I found out, I was replacing the water input solenoid, in a washing machine, I was doing some voltage checks, and it was still live with the socket turned off. Before starting to touch wires, I always disconnect the plug, and not rely on a switch, that particular day proved a life saving policy.

 

After sorting the crossed wiring and fixing the washing machine, I spent the rest of the day checking all the sockets. The house did not have an earth leakage trip, as it was built in the late 60's early 70's,

 

Tip:

I have one of those three neon light plug in testers, in fact I have one on the boat too, to do a quick check when connecting to shore power, it simply tests for crossed Live Neutral, and wrongly connected earth wiring. If all is well, then all three neons are lit to the same brightness. I guess maybe not totally fool proof, as it may not pick up high resistance connections due to the small current taken, but a good starting point. the next test I do, is to test trip the rcd on the supply post, then the rcd on board, if all work ok, we can then use the power, and sleep tight. So far in 8 years of having electric hook up, I have never found a faulty supply. I have however, come across seversl posts that have had the socket ripped out of the post, after a skipper has set off with the shore power lead still attached.

Edited January 11, 2017 by RD1

[cuthound]

I have however, come across seversl posts that have had the socket ripped out of the post, after a skipper has set off with the shore power lead still attached.

Ah yes, the fabled orange mooring line

[system 4-50]

Is it worth emphasizing for the benefit of non-experts that might be reading this thread that in electric-speak Low Voltage AC is 240V not 12V? (in layman's terms)

[RD1]

Is it worth emphasizing for the benefit of non-experts that might be reading this thread that in electric-speak Low Voltage AC is 240V not 12V? (in layman's terms)

In quite agree, I have worked on projects with switch gear for 400kV power generation and distribution systems, and in electrical terms 240 volts is indeed classed as low voltage.

 

I think the layman probably has the attitude that if you can grab it and it doesn't hurt, it must be low voltage, 9 volts, 12 volts and with dry hands, even 24 volts dc, but when you get to 48 volts and grab things with wet hands then things start to tingle. We have all tested a 9 volt battery on the tongue, and it fizzles a bit, but just increase that to 12 volts... boy oh boy, you will be thinking of the film the "Green Mile" before you know it lol.

 

The industrial 110 volt ac yellow transformers convert 234/240 V ac to 110V ac, but centre tapped to earth, so if you grab one of the connections with one hand, and have your other hand on an earthed object, you get a shock of 55 volts ac, not 110 volts ac, so uncomfortable, but less chance of killing you.

 

Don't forget, it's not necessarily the voltage that kills you, but the current, a few mA say 30mA or more can kill, it's just that you need a high voltage to overcome the normal resistance of the human body.

If you have intravenous appliances in your body, a small voltage across the devices can kill, this is why medical equipment is tested to have the lowest leakage currents than domestic equipment.