Chris, Mike,

Many thanks.  I intended to send directly to Jim, but forgot to change the To: 
field.  Yes, the colours are as you describe.

Regarding getting the polarity the wrong way round, in the mid-1960s one of my 
colleagues was called upon to design a power supply with 12 V output at some 
amps.  The output capacitance required was a quarter of Farad made up of 25 x 
1000 µF capacitors connected by busbars.  The prototype came back from the 
workshop and he plugged it in.

At point he realised two things: (1) the workshop had got every one of the 
capacitors wrong way round and (2) the mains switch for his bench was located 
behind the unit under test.  He walked quickly toward the big red button at the 
end of the lab but didn't get there quickly enough.  There was a colossal bang 
and we had a well-decorated ceiling.

73
John F5VLF

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On 29/11/2008 at 09:12 Chris Trayner wrote:

>Hi John,
>
>
>You saw Jim's reply, but
>
>> a grey stripe with a 0 on it and this is adjacent to the shorter of the
>two leads.  If I recall correctly, this is the negative lead,
>
>Is it a rather oval 0?
>The tradition seems to be a grey minus (rounded rectangle) within a black
>oval within a grey band on a black background.
>A case of not quite making up their minds what the colour scheme is? ;-)
>
>You may also find some (for want of a better term) crease lines on the
>exposed metal end of the can. I think these are purposely weak so that if
>it goes it blows there, with little containment (in the explosives sense).
>I can vouch for this, as from time to time one of our students puts one
>wrong way round on the 15V line. They go off with a very satisfying bang!
>... followed by other students crowding round the bench to see what had
>happened. The end of the can shears along the crease lines and the bits
>peel back like petals, allowing fluffy stuff to be ejected fairly
>harmlessly.
>
>73,
>Clank