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#144813 01/22/06 09:15 AM
Joined: Aug 2001
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Again, this is all just stories I've heard.

And those stories are quite correct. [Linked Image] BS546 was certainly used with DC supplies in the past, both the 2- and 3-pin versions.

As you say, when a 2-pin plug was used on a live-chassis AC/DC radio or TV, the user had to reverse the plug in the outlet if it didn't work on the first attempt (the tube filaments and dial lamps would glow, but with incorrect polarity there would be no HT/B+ voltage).

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If you had a 3-pin plug, you'd have to undo the connections and reverse them.
Yep -- Which meant that if you had a radio with color-coded cord and lived in a house fed from the negative "outer" pole of the supply, you'd need to deliberately connect red to N and black to L in the plug, the opposite of normal.

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The BS1363 plugs, at least the older versions, carried "AC ONLY" warnings on them.

I don't recall seeing BS1363 plugs so marked, but some sockets certainly were. I always thought it was primarily where the switch wasn't a quick-break type and thus unsuitable for DC.

So far as I'm aware there was nothing in the original BS1363 specification which limited their application to AC. When BS1363 was introduced in the late 1940s, a good many older urban areas still had DC supplies.

#144814 01/23/06 06:06 AM
Joined: Dec 2002
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djk Offline
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Potentially having the fuse on the neutral would possibly liimt their use though ?

#144815 01/23/06 07:55 AM
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The fuse would still be in whichever side of the line was "hot." As far as the connections in the house wiring were concerned, there was no difference whether the house was fed from the positive or negative pole.

The black/N terminal of all sockets was still connected to the incoming neutral and thus at earth potential. That just meant that the red/L terminal was at +200 to 250V in some houses and -200 to 250V in others, hence the problem with a radio not working if taken to a house on the opposite pole until its wires were swapped in the plug.

Either way, the fuse would still be in the ungrounded conductor.



[This message has been edited by pauluk (edited 01-23-2006).]

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