Just 'coil them up' (into coils that are not too small in diameter, maybe 150-200mm) and use tape or something (or even just wind the ends around the coil) to keep them coiled.I’ve amassed quite a few cable off cuts ( still a few metres long) that are no longer on their reels. How do you guys store these in a shed as mine are complete spaghetti at the moment.

someone will nick it!Don't store it outside.
Just 'coil them up' (into coils that are not too small in diameter, maybe 150-200mm) and use tape or something (or even just wind the ends around the coil) to keep them coiled.
Yes, I occasionally do that, and sometimes also write on the CSA, if there is any risk of that being in doubt.To make the coiling even more useful - measure the length first, and add a label, or write it on the sleeve. Saves you uncoiling to find the peace is just 1m to short for the job.
Do you mean 'exposed to elements', which I don't think many people would consider doing (although it would probably not result in much harm)?Don't store it outside.
Cable is very often stored in garages/sheds etc., and I think that's fine.

A new twin and earth reel was left outside for years, and eventually the insulation resistance came under 2M ohms.Do you mean 'exposed to elements', which I don't think many people would consider doing (although it would probably not result in much harm)?
That surprises me.A new twin and earth reel was left outside for years, and eventually the insulation resistance came under 2M ohms.

Fair enough. Thanks for your input.That surprises me.
I am now many years (can't remember exactly how many!) into my experiment with a length of PVC T+E (and lengths of other types of cable) submerged in brine, and it remains fine in terms of IR. I also have some 'totally exposed' T+E clipped to the side of my house which has been there for at least 40 years and, again, still remains fine.
That would obviously be a very different matterFair enough. Thanks for your input. ... It could have been that rats or whatever else may have chewed on the cable which resulted in a much lower IR value.
It's UV light, not water, that can eventually damage PVC-sheathed cables, but it's only the sheath (and therefore should not affect IR) and, in any event, the main thing that can sometimes happen is that the PVC sheath becomes brittle - but that's not really an issue if it is not 'disturbed' (e.g. if, as in my case, it is clipped to a brick wall.)However, leaving a cable exposed outside to the rain or extense heat does lower IR values. Think about it, a cable exposed in a damp wall does eventually wear it out internally.
If just looked back through the forum archives,and have found that in July 2017 I wrote ..However, leaving a cable exposed outside to the rain or extense heat does lower IR values. Think about it, a cable exposed in a damp wall does eventually wear it out internally.
The experiment continues, still with fine IR results on all the cables, and has clearly now been going on for well over a decade.Talking of submerging cables in liquid, my occasionally-mentioned long-term experiment continues, and has now been going for 3 or 4 years. I have ~2m lengths of both T+E and ("50V") alarm cable submerged in brine, and periodically IR them (from cores to brine). At the last count, both were still showing >1,000MΩ at 1000V.
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local