Does anyone know what this is?

[LmarshallSparks]

Hey all, I’ve come across an external stopcock which locks to me as though it’s missing a stopcock? Any idea on how to isolate the water here?

Thanks in advance

 

[Chuck]

IIRC, there would have been a yellow (?) key provided when the stopcock was installed. If this has been lost, ask your water supplier if they can let you have a replacement or tell you where to get one.

If not, use a pair of callipers, or a metric socket set, to gauge the distance across the flats. I think it's probably 10mm but I may be wrong. Get a cheap 'T-handled hexagon wrench' of this size from a tool shop, attach a luggage label saying "For outside stopcock. Use gently!" and keep it somewhere you'll be able to find easily in an emergency.

If you use sockets as gauges, make sure you clean any grease/oil off them first and also wipe the stopcock's hexagon clean after. You want to avoid the possibility that the grease would cause the plastic to 'perish'.