Sounds like a classic dual edged problem of...
(1) semi-competent tradesperson..
(2) lack of formal written contract agreement before any work commenced!
Mix the two together on the same job and total carnage and mayhem can result.
If its one of these walk-in showers with a long shower tray, (you say 1500mm), then it could be argued that the far-end of the tray is not in the "showering area" …..
i.e where shower jets would normally be expected to be directed..
Bog standard shower enclosure is 760mm x 760mm
Allowing for 600mm zone to the side of standard 760mm enclosure would be 1360mm..
Even working backwards from 1500mm far wall - 600mm zone still leaves 900mm worth of shower area..?
We have a 1000mm x 850mm shower tray with a single glass wall and an open end on the narrow 850mm side 1000mm from the mixer shower..
Even with NO door, at 1000mm from shower wall we don't get any significant water flying out of the enclosure..
so I guess it could be argued that 1500mm is reasonably safe...?
Personally I would not do what you have described..
BUT.. it may not be any more dangerous than any electrical accessory if someone decided to throw a cup of water over it!?
opcorn :C
Just Pondering?