PoE

Devices that are PoE, is their a limit to the distance of the cable from the PoE injector?

Standard data / structured cabling rules apply, so less than 100 metres

(although in practise they ought to be able to run farther if the overall power draw isn't huge)

A reasonable assumption but I was thinking it would be a lot less. Good to know that this is not the case.

The IEEE standard for PoE sits under the same umbrella of standard as Ethernet 802.3, so cabling / physical limits etc are all the same

The standards take into account the power lost due to cable resistance. A handy table https://www.trend-networks.com/power-over-ethernet-c... - you can see the power source equipment (PSE, typically a switch or PoE injector) can supply more than the powered device (PD, typically an AP, camera or phone) may consume.

This does assume your cabling actually meet the standards - if it is some no-name brand CCA/CCS which purports to, but doesn't, then you could have issues on long runs where the PD is consuming the maximum permitted.

Hopefully the cabling isn't too long for the OP - shouldn't really be for most domestic installs - unless its a premier league footballers McMansion 😅

As said anything under the 90+10 metre (90 metres of solid-core + 10 metres of 'cordage' aka stranded conductor patch lead /fly lead / work area cables) will be golden.