Electrical equipment linking birch and shrub (6,3)

I believe the answer is:

switch box

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'electrical equipment linking' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'birch and shrub' is the wordplay.
'birch' becomes 'switch' (I've seen this before).
'and' is a charade indicator (letters next to each other).
'shrub' becomes 'box' (a box tree or shrub).
'switch'+'box'='SWITCH BOX'

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I've seen this clue in The Guardian.

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