Is there a special tool to tighten lock nut on mono block tap under a kitchen sink , tap has a large nut around 30mm and limited access under sink.?
Box spanner or adjustable basin wrench
Depends if they pass through it or notSurely a box spanner will only work if you feed the hot and cold flexi pipes through it first.
I too would try the adjustable tap wrench though.
Depends if they pass through it or not
No, not thinking of those, if I was I’d have said a monobloc spanner. That said, I can’t recall that I’ve been seen it where the pipes don’t pass through.Sorry CBW, I was in the process of editing my post when you replied.
I am not a plumber but I cannot recall seeing a kitchen sink monobloc that has a fully circular brass back nut that doesn't have the hot and cold running up inside the nut.
As per my edit, I think you are possibly thinking of the horseshoe back plates.
Not possible to use box spanner and although I can just get an adjustable basin wrench on it there is no room to turn it.
I need a split ring spanner like in this set, but no dimensions given.
https://www.toolstation.com/tap-backnut-tap-connector-set/p43610
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