US/UK Mains, kettles, etc.

[prpr]

I've had UK 240V mains shocks about 6 times in my life, and only once was it my own stupid fault

So what were the other 5 caused by? Seems rather excessive to me. I've only had one mains (and one HV D.C. off a valve amp.) and that was my own stupid fault - luckily I was on the right side of a series capacitor and a poor earth.

 

[prpr]

much as many of us still call ours 240 and 440 volt

Where do you get 440 from? √3 times 240 is 415.

The nominal voltage is 230, but you forget to state the tolerance, which is -6/+10%, which is why we still use 240 and Johnny Foreigner in the EU still uses 220, although we are all harmonised (for now!).

 

[Black Hole]

I think you're right about 415, but I feel sure I have seen "440" somewhere.

 

[MikeSh]

440 is a number I've often seen over the years, on warning signs too, not just written in places like this. I don't know where it hails from and I don't use it myself.

I'm well aware of the tolerance business and I remember when the standard UK voltage was 'changed' from 240 to 230. It does make some sense and I don't see it changing back because we leave the EU - it's a more international thing than just that.

 

[BMAX]

Slightly off topic, talk of phases reminds me of a situation some years ago when my employer, who manufactured three phase equipment, moved premises to Liverpool. Apparently Liverpool, retains the phase rotation (R,B,Y) used by the old local generating company. which is the opposite to everyone else on the National Grid.
Connection to the Grid is via the 'Liverpool Cross'.

When I asked how the plant department coped with their fans and motors, they said 'Ah! we know to connect them so that they work correctly'. They absolutely refused to wire our test bay incoming three phase supply to the national standard,

We ended up installing a 'black box' translator link between the incoming feed and our test bay, crossing the blue and yellow phases, so that our test engineers did not need to know about this oddity and thus avoid mistakes.

 

[MikeSh]

When I was a commissioning engineer in building services the first check when starting a 3 phase fan or pump was to give it a short kick and check which way it turned. The electricians rarely bothered which wire went where, so it seemed to be about 50-50 right to wrong. (To be fair, if they were still around they'd often ask what to do.) Swapping a pair of phases was regular work
It could get more interesting with star-delta machines. I did take out the odd fuse or two with them

 

[EEPhil]

but I feel sure I have seen "440" somewhere.

440 is a number I've often seen over the years

Ditto. I'll end up searching through any old notes I can find to see if I can make sense of that. 440V rings a bell!

 

[EEPhil]

Having had a general look around it seems we are not the only ones who have seen 440V mentioned.
I wonder if this is the cause of the 415/440V confusion.
The following is a nameplate from a motor that was part of a research project c2000.

It appears to have two sets of values. One for 50Hz and the other for 60Hz.
Voltage (50 Hz) 380-415, (60 Hz) 440-480.