Electrical safety mats in workshops

[Capitol]

Keep buying the life insurance!

[Mike Barnes]

I suppose it's just about possible to work the toaster with slippered feet...

[Fredxxx]

I recall some aerial cables being live as a result!

People are wimps these days!! :-)

[Cursitor Doom]

That's what I often do, too. I don't trust neon screwdrivers. Nice to know I'm not alone!

[Andrew Gabriel]

Actually, they measure the *Voltage* between real ground, and the earth conductor in the building, hence became known as Voltage Operated ELCB's. They were required to trip before the voltage between real ground and the earth conductor reaches 50V. Their purpose was not to prevent electrocution, but to prevent a fire when there's a short to earth, but the earth impedance is too high to blow the circuit fuse, so the current will otherwise just carry on flowing, unless/until the resistance in the path burns out and/or causes a fire.

The term "RCD" was as a result of the BBC program "That's Life!" getting all the manufacturers to agree the same simple name for plug-in RCDs. They all thought Current Operated ELCB" was too complicated, and invented their own different names, confusing the market and hindering adoption.

There has never been strong agreement on the name when applied to RCDs as part of the wiring installation, and RCCD is still seen. Original name was current operated ELCB.

[Johnny B Good]

I'm pretty sure Graham meant, "As I endlessly tell my wife at breakfast time, you shouldn't operate electrical stuff whilst bare footed." :-)

[Graham.]

Operate a toester? (see what I did there?)

[Bill Wright]

I operate it with my hands, normally. I do sometimes switch the leccy fire on with my toe though.

Bill

[Bill Wright]

It's good to have a contributor from the spirit world!

Bill

[Johnny B Good]

I'd do the same with my fan heater except it uses rotary switches. :-(

[Nightjar]

IMO you would probably get more benefit from buying anti-fatigue mats. In many decades of running a light engineering factory I've never had a properly installed industrial machine have the body become live. However, standing for long periods on a concrete floor is tiring.

[Capitol]

Agreed. The black rubber interlocking ones from Costco are remarkably tough IME and very comfortable.

[damduck-egg]

I thought Whisky Dave fulfilled that Role

G.Harman

[John Rumm]

[Martin Brown]

I can't see an electrical safety mat being much good once it gets covered in metal swarf from a lathe unless you only ever work on plastics. I can see some point in having one of those tacky mats that take most of the swarf off the soles of your shoes at the exit.

RCD shouldn't care about line impedance merely the extent of the inbalance caused by a leakage to earth.

[The Other Mike]

For comfort and avoiding slips from coolant a grippy mat or a duckboard is good to have, for electrical safety there is no need for anything if the machine is properly wired, earthed and protected. If in any doubt rewire from scratch using new switches and motors where necessary.

[Adam Funk]

What's used as the "real ground"? If a real ground is there, why isn't the earth conductor just tied to that to provide better earthing throughout the building? (I'm not being deliberately obtuse here --- just curious.)

[whisky-dave]

I thought it was more to do with control as in keeping the misses in the kitchen, barefoot and pregnant. It's their careers afterall ;-)

[tabbypurr]

Iso transformers aren't sufficient to prevent shock, as I found the hard wa y.

Most valve radios used a mains transformer. Transformerless 'universal' set s were common at the bottom end of the market. Transformerless was also use d in dc mains areas, with both +ve & -ve earth. Universals were a known cau se of shocks, eg from grub screws that had been retightened but not rewaxed . There were lots of unpolarised 2 pin sockets around at the time.

ELCBs serve 3 purposes.

1. When Frame voltage reaches shock risk they disconnect power, thus elimin ating a major shock risk with earlier TT installs.
2. Cutting power in that situation also eliminates a fire risk
3. This means they effectively make ineffective earths safe. But they don't offer the extra mode of shock protection RCDs are famed for.

earth rod = real ground. Rest explained above.

NT

[Capitol]

Up to probably 1965, parts of London were DC, hence transformer sets were not that popular.