So unscheduled stuff can happen where people can turn up, wondering seen as it's visible tent can I turn the fan and light off for few hours during 18 hour period if yes how can I make up for this time lost? do I start 18 from beginning or continue where left off? can it damage the plant
As long as it doesnt get more than 12 hours of straight darkness then it wont flower, no harm done at all, you just lose out on a bit of growth. Even one or two days won;t trigger the plant completely, so it should be fine.
Nah you will be fine I go through this about once a month. Dark during the light period doesn't really stress them much but light during the dark period is a no no.
Giving them light while they are in the dark period of their cycle is only a real problem during flower. That being said, your plants like/want to have a schedule. Fucking with them is just going to stress them out and cause you more problems in the long run. If you can't give them the schedule they need, you should reconsider the location of your grow.
Na in my grow cab I have to cut new holes to raise the lights, took me about an hour after fastening everything and re-pinning the reflective material before the lights went back on. No problems yet.
It's fine, Some greenhouse growers using supplemental lights during the winter will either turn the lights on from 5pm-10pm others will turn them on from 1am-5am others will simply turn them on at night from 10pm-4am. Doing the last way will give it a 12 hour day light cycle with 2, 2 hour nights and another 6 hour day in a 24 hour period just to interupt from flowering.