Temporary Housing Park Service Demand

ScopeAfter a large disaster, displaced households live in travel trailers and manufactured housing units on group sites, and the two look alike on the ground but are calculated differently in the NEC. A travel trailer park falls under Article 551, where each site is loaded by its receptacle -- 50 A sites at 12,000 VA in the 2017 and later editions (9,600 VA before), 20 A and 30 A sites at 3,600 VA, 20 A only at 2,400 VA, tent sites at 600 VA -- and the demand factor from Table 551.73(A) drops steeply as sites are added. A manufactured home park falls under Article 550, at 16,000 VA per lot or the calculated load if larger, with the Table 550.31 factor. The demand factor tables are NFPA text and are not reproduced: the factor is entered from the adopted edition for the site count. Forty 50 A sites with a 0.41 factor is 480,000 VA connected and 196,800 VA of demand, or 820 A at 240 V single-phase; at the pre-2017 value the same park is 157,440 VA and 656 A, so the edition change alone adds 25% to the service. Twenty-five manufactured homes at a 0.24 factor is 96,000 VA and 400 A -- less than half the travel trailer park's service. Both articles are shown side by side because FEMA group sites have used both kinds of unit, and a park designed to the older 50 A value may not meet the newer one. A service and feeder demand estimate only: it does not size site feeders, pedestals, or conductors, or address voltage drop, grounding and bonding, GFCI, or water, sewer, and site layout. Utility service requirements may differ. The NEC edition adopted by the AHJ, the utility, and the AHJ govern.

Formula or tableRV park: connected VA = sum of sites x per-site VA (50 A 12,000 VA in 2017 and later or 9,600 before; 20 A + 30 A 3,600; 20 A 2,400; tent 600); demand = connected x entered Table 551.73(A) factor. MH park: demand = lots x max(16,000 VA, calculated lot load) x entered Table 550.31 factor. Current = demand / V single-phase or demand / (sqrt(3) x V) three-phase.

Source and editionNFPA 70 (NEC) Section 551.73(A) and Table 551.73(A), recreational vehicle park demand, and Section 550.31 and Table 550.31, manufactured home park demand, cited by number with the edition flagged. The demand factors are USER INPUTS read from the adopted edition's tables and are not reproduced.

Free accessFree read-only access at nfpa.org/freeaccess. The tile reproduces no NEC table; the user enters the demand factor for the site count from the adopted edition.

What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.

API field namessites_50a_count, sites_30a_count, sites_20a_count, tent_sites_count, nec_edition, rv_demand_factor, mh_lots_count, mh_lot_va, mh_demand_factor, service_voltage_v, phase, rv_connected_va, rv_demand_va, rv_current_a, rv_other_edition_demand_va, rv_other_edition_current_a, edition_change_pct, mh_connected_va, mh_demand_va, mh_current_a

• 50 A RV site value by edition 12,000 VA in the 2017 and later NEC, 9,600 VA beforeNEC 551.73(A)
• 16,000 VA per manufactured home lot or the calculated load if largerNEC 550.31
• Demand factor entered read from the adopted edition's Table 551.73(A) or 550.31 for the site count; not reproducedNEC 551.73(A), 550.31