Wi-Fi cameras
or PoE?

Power over Ethernet: power delivered over the same network cable, with no need for an extra socket where the camera is. The twisted-pair cable that already carries the data also carries the power, supplied by the recorder or by a PoE switch with enough power for the number of cameras connected. In practice this makes installation much simpler: nobody has to add a power point on the façade, and if a camera fails or freezes you just unplug and reconnect the cable at the switch to restart it, without climbing any ladder. There are different PoE standards depending on how much power they deliver, and higher-resolution cameras or ones with a built-in floodlight need more watts than a basic camera, so check that the recorder or switch you already have can supply the power your chosen camera needs before you buy it.

You avoid the data cable, but the power cable almost never goes away, unless you opt for a battery camera with all the limitations that brings. A Wi-Fi camera that records continuously draws power constantly and needs a permanent socket at the exact spot where it's mounted, which on a façade or in a warehouse almost never exists beforehand. In most cases you end up calling someone to run power to that point, exactly the same job it would take to run a network cable. The real difference isn't whether cable is run, but which one: a power cable that only powers, or a network cable that powers and also carries the picture without depending on the local Wi-Fi. Before choosing Wi-Fi to avoid building work, check whether the spot already has a socket nearby; if it doesn't, the saving you imagined doesn't exist at all.

They solve the socket problem in exchange for another one: they don't record continuously, but wake up on motion detection and start with a slight delay before actually recording. That first second or two, which is usually exactly when the face of whoever enters the frame is visible, is almost always lost. Add to that the upkeep: they need recharging every few months, and the more battery cameras you have, the more times a year you have to take them down, charge them and put them back up, with that spot uncovered while they charge. They're a reasonable solution for an occasional, low-risk spot, but not for the camera that really matters, the one on the door or the till, where the start-up gap and the periods without battery weigh more than the convenience of having no cable.

They can, and it's an effect that surprises people who haven't experienced it before. Unlike a phone or a laptop, which use the network now and then, a security camera transmits video practically constantly while recording, which places a continuous load on the router that no other household device generates. Two or three cameras sharing the same Wi-Fi network with the TV, phones and video calls are usually noticeable, especially if they're far from the router, with walls in between, and transmitting on the 2.4 GHz band, which besides having less bandwidth is usually already crowded by the neighbours. The answer is to separate the camera network from the home network whenever the router allows it, use 5 GHz where it reaches reliably, and not assume it's just one more device before checking it in real use for a few days.

PoE starts with an advantage because the signal travels over a physical cable that can't be intercepted or degraded from outside the property, whereas a Wi-Fi signal can be swamped with noise on the same band or, in extreme cases, blocked with a jammer. That isn't the typical scenario for an opportunistic home burglary, but it is a real risk for businesses or industrial units where someone can study the installation before acting. That said, in the vast majority of cases what compromises a camera's security isn't the transmission medium but the password on the recorder or the app that controls it, which, if weak or left at the default, leaves the door open regardless of whether the camera is Wi-Fi or PoE. Change that password, update the firmware and don't expose the recorder directly to the internet without protection, and the difference between Wi-Fi and PoE takes a back seat.

Yes, and in fact that's what we end up doing in quite a few real installations: PoE for everything that can be cabled without complications, and a single Wi-Fi camera in the one place where running cable would be out of all proportion, such as a shed at the bottom of the plot or a spot on the other side of a courtyard. What matters is that all the cameras, Wi-Fi or PoE, record to the same recorder and are managed from the same app, rather than ending up with two separate systems, two different apps and two footage retention periods that nobody checks in the same way. That fragmentation is the usual mistake when someone adds a Wi-Fi camera of their own to an existing PoE installation: the camera works, but it's no longer a single system; it's two systems that happen to share the same wall of the house.

One hundred metres from the switch or recorder to the camera is the standard limit for network cabling, and that distance comfortably covers practically every home, shop and normal-sized industrial unit. When the real distance exceeds that limit, for example in a very long unit, between two separate buildings or on a large property, the solution isn't to push the cable further but to add an intermediate PoE switch that receives the signal and redistributes it from a point closer to the camera. It's a calculation worth doing with an actual plan of the cable route before buying anything, because finding out with the cable already bought and cut costs more than planning it in advance. In normal home installations this limit is almost never the problem; where it does crop up often is on large plots, industrial estates and properties with several separate units.

That's precisely the case where Wi-Fi clearly beats PoE. The solution is to put Wi-Fi cameras where there's already a socket nearby, without drilling walls or fitting trunking, accepting from the outset that quality and stability will be somewhat lower than with a wired installation, and that the day you move out the cameras go with you without leaving anything installed in the property. Choose a good Wi-Fi access point, place the cameras as close to it as possible and use the 5 GHz band if the range allows, to minimise the drop-outs and reconnections that are the usual problem with this kind of installation. It isn't the ideal solution, but it's a perfectly reasonable decision when taken knowing exactly what you're giving up in exchange for not doing building work in the property.