Special Occupancy Load Calculations
Article 220 Parts V–VII, 551.73, 550.18 and 550.31 (Farms, Health Care, Marinas, RV Parks, Mobile Homes)
NFPA 70 National Electrical Code, 2023 edition · Reviewed 2026-09-21
The Florida exams test these as demand-factor arithmetic. Where the tables live in the 2023 edition: RV parks — 551.73 with Table 551.73(A) (inside Article 551); mobile home feeders — 550.18 with Table 550.18(B); mobile home parks — 550.31 with Table 550.31 (inside Article 550); marina shore power — Article 220 Part VII, Table 220.120, applied through 555.6; farms — Article 220 Part V, 220.102/220.103; health care receptacles — Article 220 Part VI, Tables 220.110(1) and (2). Written from the 2023 text.
1. RV parks — 551.73
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(A) basis per site, not less than: 12,000 VA for a site with a 50 A 208Y/120 V or 120/240 V supply; 3600 VA for a site with both 20 A and 30 A; 2400 VA for a site with only 20 A; 600 VA for a dedicated tent site with only 20 A. A site with more than one receptacle is calculated on its highest-rated receptacle; a pedestal serving two sites (551.77) is calculated for the two highest-rated receptacles only.
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(B) demand factors — Table 551.73(A), applied to all sites: 1 site 100 % · 2 = 90 · 3 = 80 · 4 = 75 · 5 = 65 · 6 = 60 · 7–9 = 55 · 10–12 = 50 · 13–15 = 48 · 16–18 = 47 · 19–21 = 45 · 22–24 = 43 · 25–35 = 42 · 36 or more = 41 %. Amenity loads (service buildings, pools) are calculated separately and added. Neutrals to RV site distribution are not reduced (551.72(D)).
Worked example (the Code's own IN): 20 sites, each with 20 A + 30 A → 20 × 3600 VA = 72,000 VA × 45 % = 32,400 VA (1620 VA per site).
Worked example: 40 sites, all 50 A → 40 × 12,000 = 480,000 VA × 41 % = 196,800 VA; at 120/240 V single-phase: 196,800 ÷ 240 = 820 A.
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