Isolated mains voltage - why not as standard?

[Cursitor Doom]

55V doesn't constitute a "belt" in my book. Can't feel anything at all below 80V; that's the point when I first feel a slight tingle.

[Cursitor Doom]

Er, that's what I said.

[Tough Guy no. 1265]

Which wouldn't be needed if they simply removed the earth from the neutral. And remember RCDs never used to exist.

[Tough Guy no. 1265]

And if they were isolated, you'd get no belt at all, so not jump and fall off your ladder.

Anyway, every time I've seen one of those yellow builders transformers for sale, it's referred to as isolating.

[Tough Guy no. 1265]

You were taking about sensitive equipment, I was talking about people.

[Cursitor Doom]

What are you going to do about safe tea? You'll have no earth on your metal cabinets.

[Tough Guy no. 1265]

Exactly, no earth to be leaning against when I accidentally touch the live on a damaged cable etc, which wouldn't matter anyway because the live would have no voltage WRT ground.

Isolated mains IMPROVES safe tea.

[Cursitor Doom]

I suppose these days with more and more STUFF coming in double-insulated plastic encapsulations, there may be SOME merit to your argument. We'll just prematurely scrap all the metal-cased appliances, then. Happy?

[Tough Guy no. 1265]

Isolated mains improves safety with those too.

[Johnny B Good]

In dry conditions, 55vac might only give you a mild 'tingle' but on a building site working in the rain, it's a different story, you will get a bit of a belt (but with far less risk of electrocution than if it were a

240v contact or even 120v).

These site transformers provide a bi-phase 110v supply to the tools, the centre tap on the secondary is connected to earth to prevent either of the phases rising to 110v with respect to earth in the event of an earthing fault on the opposite phase.

[harry]

Nearly all accidents occur when two unlikely factors coincide.

[harry]

ashing machine and your fridge both having a fault with the opposite conduc tor, and you touch both. So very unlikely.

ive. The only shocks I've ever had were worn cables on a mower, touching a switch with wet hands when outside, etc. Now if the supply had been isol ated, I wouldn't have received a shock.

You won't observe a fault where a chassis becomes live because it is earthe d. One of the faults could be miles away.

[harry]

They are 110 volts, centre tapped to earth so there is 55 volts to earth.

[harry]

Batteries are only safe because they are usually only low voltage.

[harry]

Drivel. Try the experiment stood in the bath. Or with wet feet/hands, touching earth.

[Brian-Gaff]

Do you mean a transformer so one side of the mains could be earthed even on a hot chassis device? Most test set ups tend to be this way of course, but to do this with the whole supply to a home would need a very big transformar? Brian

[Cursitor Doom]

Oh I don't know. He's probably replaced all his fuses with nails 'cos they blew once in a while.

[Cursitor Doom]

Why would I want to do that? Of course one's skin resistance is massively reduced when wet, consequently raising the risk of severe shock and electrocution. In dry conditions, however, I personally can't feel

*anything* under 80V. YMMV.

[Dave Plowman (News)]

Generally, because the tools are 110v.

Going back years in TV studios, any domestic equipment or musical instrument that needed mains power was fed via an isolating transformer.

These days, using an RCD provides the same safety requirement, and at far less cost.

[Tough Guy no. 1265]

Why would a TV studio be a dangerous environment?