In article ,
wrote:
On Monday, 26 December 2016 14:45:24 UTC, Dave Plowman (News) wrote:
TLC sell 'bridge' units that connect any two standard metal boxes
together at the right spacing for the plates.

FSVO plates, possibly.

Personally I dislike abutted flush faceplates.

A couple of conduit bushes and a coupler will tie boxes together nicely.

Done that plenty of times on the surface.

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from KT24 in Surrey, England