I charged by time. The batching plant at T5 when working there, would take two of us, two days to test, it was defiantly portable, the wheels still attached, it would go site to site as 22 articulated loads, so pricing per item can never work.
It also depends on the tester used, we had top of range Robin, when plugged in it did a self test first, including testing the supply, the minium times were set as in the guide for auto testing, and I timed myself doing an office with some 110 volt stuff as well, I was there until picked up, so no real hurry, but out of interest tried to work as fast as I could, due to fixed test times, and a lot of class I, I worked out average of 60 items per 8-hour day, which was a lot slower than I expected.
However, later in University watched some PAT testing being done, with a battery powered device, this resulted in no self test, and they could do 100 items in an 8-hour day.
Back in 1985 my time was being charged out at £25 per hour, I was not getting that, but for industrial work the fee today must be far higher, we must be looking at £200 a day now, so 3 to 4 days work, so call it 30 hours to test 300 units, 10 an hour if moving room to room is going some, so we are looking at around £4 per unit if one is doing the job correctly.
Of course, you can walk around with a role of pass stickers on one's belt, make no record of each item tested, and with class II equipment if it looks OK bang a sticker on it. So you can inspect 20 items an hour, but not if you need to produce an equipment register, etc.
Where the client wants you to add to the existing records to show a trend, so the plant number is never changed, and you have a list with loads on the list locked in cupboards which people need to unlock for you, it can take a lot longer, but if you can set up in a room and items brought to you, then clearly a lot faster.
I stopped doing PAT Testing a few years ago, because people were all undercutting each other and there was even a local charity doing it for free !
I also found the same, so I only did PAT testing after a repair before returning an item to service. And I did find many errors with items PAT tested, mag mount drill, tested as one class II item, when the mag mount was class I and only the drill class II, and no earth connected. The same with computers, there only the computer was tested, not the lead set. They were getting away with it, until the safety officer tried to give us a lecture on how we should check items had the valid sticker on them before use.
I said if we did that, the job would stop. He of course said nonsense, at which I got up and walked around the room pointing out how many items in the office he was giving the lecture in did not have valid labels, including the projector he was using to give the lecture with, which kind of stopped the lecture in its tracks. You only need one smart twit like me and the whole job can stop.
He has upset me earlier with a test, it asked what you do if the item is not PAT tested, with four tick boxes, non of which said get the tester out and test the item, so wrote none of the above. This did not go down well.
