Working out how many reels a job needs looks like simple division and it is not, because the division has to be done per cable type and then adjusted for the fact that reels do not arrive or get used in whole numbers.
The base calculation
Total planned length, divided by the length each reel will carry. That length is not the reel’s maximum – it is what you choose to put on it, and choosing it is the first decision. A reel rated for more than you need is wasted weight; one wound to its limit leaves no margin and raises flange stress.
Then round up per cable type, not on the total. Rounding up once on the grand total gives you fewer reels than rounding up per type, and the shortfall lands on one particular cable.
The offcut margin
Every reel that is opened and not finished leaves a remainder, and on a job with many short runs the remainders add up. On long continuous runs the margin is small – a few per cent. On drop cable work with many individual drops it is much larger, because each drop ends and the next starts on a part-used reel.
If you have done similar work before, use your actual figure. If not, ask a crew what they usually throw away; the answer is usually higher than the estimate in the plan.
Spooling strategy
Some operations deliberately wind short reels for the last section of a job so that the remainders get used. That is worth doing and it needs planning – it means ordering a few reels wound to a shorter length rather than all to the same length.
It also means your supplier has to be willing to wind to order, which is not universal. Worth asking early.
Damage and spare
A small allowance for reels damaged in transit or on site. Reels get dropped, and a reel with a cracked flange should not be wound. A couple of spare reels per hundred is usual and cheap insurance.
And the return question
If reels are being returned, count how many empties fit on the return vehicle at the same time. A rollout that needs four hundred reels delivered and can only bring back sixty per trip is a logistics plan, not a purchase. We went into the return volume in how many cable reels ship on one pallet.
And the thing that always gets underestimated
Testing and remediation. Some length gets used for test pulls, some gets pulled and abandoned, and some gets replaced when a section fails. On a well-run job it is a small percentage; on a difficult one it is not.
Ask the crew what they usually allow rather than calculating it. Their number will be higher than the plan’s and it will be closer to reality.
Ordering a few extra reels costs very little. Running out mid-job costs a delay, and a delay on a rollout is worth far more than the reels.
What we can do
We supply plastic reels for FTTH deployment wound or empty to the length you specify. Tell us the total length, the section lengths and whether reels come back, and we will work out the count with you – including whether mixed wind lengths would cut the waste.