In article ,
"Alan" writes:

You can also get DIN rail mounting ones which fit in a consumer
unit. Actually, I bought an empty consumer unit just for mounting
these. You could fit them in a waterproof CU or DIN rail box for
outside use. The DIN rail ones are more expensive than the plug-in
appliance modules though. The DIN rail lamp module is much better
quality unit than it's plug-in equivalent though, always doing
switch on/off through a smoothed dimming operation, and it includes
a connection for operation via a momentary action switch if
required, quite separately from X10 operation. (Also claims to
support 'professional X10' whatever than is -- I think it might be
scene settings, but I don't have anything which can talk 'professional
X10' protocol to it.)

Andrew,

I found some 'X10 professional' bits he
http://www.homeautomation.eu.com/category/6

That's who I bought most of my X10 bits from. They were the
cheapest supplier I could find at the time, with a good
range of items.

I like the look of the 4 channel dimming transmitter to fit inside existing
light switches!

I need to use the wired appliance modules to control some (fixed)
floodlights, so plug-in modules won't help.

The point is, if you take a plug-in module apart, you end up
with exactly the item in your photograph -- that's just the top
half of the plug-in module. Plug-in modules are often cheaper
(although not from that supplier).

I havn't used the DIN units yet, but may try them soon. However, looking at
the one on the letsautomate website, if I fitted it into my existing CU it
would't provide any current limiting breaker functionality like a MCB so

Correct.

would need fitting into it's own box downstram from the CU. They don't

or you cut the buzz bar short and just use the rest of the CU
case for DIN rail mounted things. I used a separate CU case
as a distribution/switching box for lighting. I also included
a 3A Type B MCB to protect each DIN rail X10 dimmer, in the
hope it might protect the triac if a failed lamp arcs across.
They have a 20mm fuse on the front, but MCB's are probably
faster operating and the dimmers are expensive enough that I
would like to protect them best I can.

mention that on their website so I bet some people have them in CU's
unprotected!

--
Andrew Gabriel