ECN Forum Forums General Topics of the Trade General Discussion Area 127 Volts?

The puzzle for the day:

A friend has an old Sony radio with a line-voltage selector with positions for 110V, 127V, and 240V. I've never heard of any place that has 127V outlets. I note that 127*sqrt(3)=220, so I figure this voltage comes from a line-to-neutral connection on a 220V wye system.

Does anyone know where they're actually using 127V as a standard wall-receptacle voltage?

This is the old 127/220V WYE system used in Europe and perhaps elsewhere. It is/has been phased out. Most of the countries that used to use it are standardizing on 220 volts only. I think it's most common occurence was the old Spanish/French electrical systems. It may still be used elsewhere in the world but as to where I am not sure. Perhaps some of our non-US members can say more.

So if you use this radio at your house, and if you measured 120 volts at the outlets, maybe you would use the 127v setting as being closer to the 120 volt supply than the 110v setting?

Yes, as Ian said it comes from the old European standard which used 220Y/127 distribution networks, including parts of France and Spain.

Most of these have been converted over to 380Y/220 over the years, but I know that 127V was still in use in parts of France in the 1970s.

Belgium still has 220Y/127 distribution, but now with all loads connected phase-to-phase to get 220.

Some South American countries which were influenced by Eiropean conventions still have 127V, including, if I recall correctly, Brazil.

Old Austrian radios (until around 1970 I think) had an even weirder voltage setting... 150V! I've never heard about a 150V system being actually used anywhere, but one guy on the internet claimed he once saw a black ungrounded receptacle labeled "150V" in a rural transformer station once. He admitted not even the PoCo guy could tell him what it was intended for... but it was live at roughly 150V!
So I assume some independent rural systems started with 150V.

Mexico still has 127/220V (60 Hz) as the standard voltage and a few places, including as mentioned Brazil but also Saudi Arabia, have 127/220V (60 Hz) as one of several systems.

It was once Soviet standard as well (at 50 Hz) and I'm told old systems survive in a couple of places where Soviet engineers were active, like Vietnam. Along with American 120V, French 110V and European 220V of course...

Quite possibly one can find this voltage in other little known corners of the world.

PaulUK:

> Belgium still has 220Y/127 distribution, but now with all loads connected phase-to-phase to get 220.

I wonder where you found this info. It might be the case in a couple of small villages and even very local areas of old towns (though I doubt it) but 127V is an obsolete standard and it is very rare now. Perhaps the source of your info is quite old.

Nearly all domestic or small commercial supplies (eg for shops) in Belgium have supplies at 230V line-to-neutral or 400V line-to-line, with three phases being common for larger houses. The nominal supply voltage was altered from 220 to 230 some time back.

I had 127V in my house in New Jersey some years ago. And no, it wasn't a bad neutral. Turns out the POCO had the town distribution system mis-balanced and many people were getting excessive line voltage. Actually I had 130/260V in the house. It took the POCO a few weeks to get it corrected.

C-H
Yeah, I forgot all about the Saudis and I suspect 127 exists elswhere in the middle east too. I suspected Mexico as well, but I have heard too many conflicting reports about Mehico to say with any certainty.

[This message has been edited by IanR (edited 06-20-2005).]

The power cruises 123-125 at my house, always has.