The Kraftform Kompakt W 1 Maintenance 35 piece set might just be the ideal Electrical / Instrumentation all in one set.
I have had this set for a couple of years and simply love it. The 1/4 inch ratchet handle has a brilliant pivot head design that allows you to get into awkward spots. The set comes with 5.5,6,7,8,10,11,12 and 13 mm sockets.
The socket set also comes with a bit drive and a selection of bits.
A screw driver handle with 12 VDE blades means all the basis are covered.
A 10 & 13 mm Joker spanner makes life easy with its square set jaws and super grip setup!
The voltage tester can be handy but If I'm perfectly honest I never use this type and would always rely on an approved tester and proving unit when testing for dead.
In summary, this is a great thought out piece of quality kit that will cover you for most of your needs