Reel capacity calculator

Rope

: 1
Drum ÷ rope diameter, from the rope's spec. Leave blank to skip.

Rope weight (optional)

Standard NEMA reels

Check a specific reel

How the numbers are worked out

Packing-factor capacity (the one used to pick reels): usable annulus volume × packing factor ÷ rope cross-section area. This is the engineering spreadsheet's method. For standard reels, the usable diameter is the flange minus NEMA's clearance on each side (Section 7.1.3): 1 in or one rope diameter, whichever is larger, plus 3 in for the tire on RMT reels. The specific-reel check deducts no clearance, so it matches the spreadsheet.

NEMA 7.1 estimate (shown for comparison): the standard's round-cable formula, built on 5% nesting and 95% traverse use. Layers = ⌊(A − 2X − B) ÷ 1.9D⌋, turns per layer = ⌊0.95C ÷ D⌋, feet = ⌊0.2617 × (B + layers × 0.95D) × layers × turns⌋. It assumes cable wound evenly, so it's usually a poor fit for fluffy rope.

Weight check: rope weight is compared with the table's maximum capacity, which Section 1.2 defines as the total cable weight the reel can carry. Where the printed lb and kg values disagree, the lower one is used.

Transcription notes and discrepancies in the source
  • Section 7.1.1 prints the layer term as "19D". That gives nonsense (about one layer on any reel), so this app uses 1.9D: the radial depth ÷ (0.95 × D), doubled. This is an interpretation of an apparent typesetting error, not text from the standard.
  • Three rows have lb and kg capacities that don't match each other: Table 2-3 RM 68×38×28 (7,000 lb vs 3,630 kg ≈ 8,000 lb), Table 2-5 36×24×17 (2,500 lb vs 680 kg ≈ 1,500 lb), and Table 2-6 60×32×32 (5,000 lb vs 2,720 kg ≈ 6,000 lb). Both values are shown as printed, and the lower governs.
  • Table 2-3 RM 68×38×28 tire size prints as "21/2 x1/2", probably 2-1/2 × 1/2.
  • The weight values in Tables 2-2 to 2-7 were extracted from the PDF's text layer and checked row by row against each table's row count.

Other data in WC 26-2008

Table 3-1: Minimum drum diameters for electrical cable

Written for electrical cable insulation types. The standard doesn't cover fiber rope. These multiples are not for installation.

Table 4-1: Recommended reel covering level by product

Covering levels (Section 4.1): 1 none; 2 weather protector; 3 heavy-duty physical protector; 4 extra-heavy-duty physical protector; 5 export (wood lagging, 2 in nominal for reels 40 in and larger, 1 in below 40 in; Level 2 materials if containerized); 6 special packaging, which may be reduced to any lesser level.

"Cut to Specified Length" (NMFC 61175, Class 85) applies only when written on the order. It needs wood lagging, or 1/2 in foam under 0.090 in solid fiberboard (V3s), plus the damage-claim wording on the reel, packing list and bill of lading.

Table 4-2: Recommended packaging materials
Sections 5 and 6: Marking and handling
  • Mark both flanges with the NEMA/EEMAC class and the flange, traverse and drum dimensions. Marking is optional for Table 2-7 spools and reels with flanges 40 in or smaller.
  • Don't lift a reel by the cable with hooks or forks, and don't drop reels.
  • Roll reels in the direction that tightens the wind, on flat surfaces clear of debris.
  • Store away from chemicals and oils. Leave factory coverings on until installation. Tighten loose bolts.