The Medway Handyman wrote:

Not sure if £3 per item is that profitable?

Well it worked for McDonalds!

£3 is profitable provided that costs are low and volume is high. This
means that:

* You're only doing simple PAT testing
(any mis-fitted plugs or blown fuses have to be chargeable repairs, not
just done as freebies).

* You're doing each test quickly and cheaply. It's a box of cables
presented to you, not a walk through a whole building spending 10
minutes hunting each one down.

* A "customer" isn't just a visit to test one kettle, it's either a
shop walk-in with it, or it's a useful volume at each site you visit.
"Useful" might vary, depending on if you're already going there anyway.
(today's office has about 150 visible PAT-testables that I can see).