I have a family member that's hopping on the smart home bandwagon and ordered a C8 hub + devices (mix of Zigbee and ZWave that will pair directly - locks, sensors, plugs, switches). The house I'm doing the install in is one-story and give or take about 12-1300 sqft.
Is there an issue with pairing all the devices (that I'm able to do minus the switches) ahead of time right next to the hub at my house to save time so I can just focus on the install? Or is this a bad idea? Happy to provide more information if needed.
It has a real possibility of being a bad idea. Everything will be joined/paired directly and once the physical install of everything is done, maybe half would resume a direct connection and there's no routing table to tell them how to recover... so there would be a flood of recovery messaging on the mesh.
I've described the downside and for me, I might take the risk because I know the steps to recover... having shot my foot enough times to learn. Do you know how to recover should the mesh fail to build in it's new home?
Pairing in-place is almost always better, but if you are in a time crunch at the new location or otherwise are under circumstances that would make it impractical, you could certainly try, with a few considerations. Theoretically, Zigbee should find new routes if/when needed. Z-Wave Plus should do the same. "Classic" (pre-500-series) Z-Wave devices may need a "Repair" in order to force them to do this (ideally only on these nodes, not a traffic-intensive network-wide repair) or to speed up the automatic discovery.
One complicating factor I see is that it sounds like you're only trying to pair the sensors here. So, when you spread them out at the new location, they may indeed need to find new routes back to the hub -- but won't immediately know anything about your repeaters/routers As long as those (most switches, plugs, dimmers, etc.) are in place by then, discovering these routes should be possible, though it may take time or a repair for that to happen, as above.
Another consideration is that for Zigbee, the hub is limited to 32 "end devices," meaning devices that connect directly to it rather than through a repeater. So, if you have more than that, you won't be able to pair them until you have at least some repeaters in place. And assumes you have enough routers/repeaters in your mix and in the right locations to help any device that may need one. This network could likely benefit from at least a few (so could pretty much any network) given that the maximum range of Z-Wave under good conditions is normally a few hundred feet, and less for Zigbee, though only actually being there will tell.
So, I agree with the above: it's not a guaranteed disaster, especially with Zigbee or Z-Wave Plus (or Plus v2) devices. But if you have time to just do everything there, it might be easier that way.
With the C-8 hub, most Z-wave devices may be able to connect directly to the hub as long as the hub is in a central location. If possible, do not put the hub at one end of the house. The exception to direct connections might be locks, which might do better with a Z-wave range extender nearby due to the high amount of traffic the lock generates.
With Zigbee devices, I would suggest installing the mains powered repeating devices such as smartplugs first. Start with devices closest to the hub and then progress outward. Once all the repeaters are in place, then start pairing the battery powered devices. If you have a good repeater network, you might be able to pair sensors in place. If not, try pairing them about 10 feet away from the hub and then put them in their final location.
Appreciate the thorough and thoughtful replies - great info here I wasn't aware of, so thank you. Think I'll give it a go based on what I've read, and if something goes wrong, it's with an understanding family member
Do you know how to recover should the mesh fail to build in it's new home?
