RV Park Demand Calculation (551.73)


New York
Electrical Engineer (NYS PE)
I am doing a small design for an RV park with 50A power pedstals, and am looking for a little clarification in regard to application of the demand factors in NEC Section 551.73.

Table 551.73(A) states that the demand factors apply to service entrance conductors and site feeders. Considering that, am I interpreting 551.73 correctly that demand factors would be selected based on two separate calculations:
1) Based on TOTAL number of sites, in order to size the service.
2) Based on the number of sites in a particular feeder circuit, in order to size conductors and the OCPD. (And that you would NOT use the demand factor based on the TOTAL number of sites).

For example, using Table 551.73(A):
1) In a park with a TOTAL of (25) 50A sites, you would use a demand factor of 42% as part of your service size calculation.
2) In the same park as above, a single feeder circuit will have (4) 50A sites, so in this case you would use a demand factor of 75% as part of your feeder circuit calculation. (And you would NOT use the 42% demand factor for this particular calculation.)

Is this accurate?
Thanks much.


Staff member
State Electrical Inspector (Retired)
Yes, Sir
(Don't see the info in your profile. Could you please tell us your relation to the electrical industry (electrician, contractor, etc).