TechRay
Member
- Location
- Livingston, Montana
As the EC, we have been asked to install the Service and feeders to Manufactured sleeping units at a Man Camp in North East Montana (Western Tip of the Bakken Oil Field). The Manufacture
has sent us their load calcs for the 3 models of units and their method in coming up with panel and feeders sizes has me concerned. To begin, these are 5 and 6 room 15' x 76' Manufactured structures, once in place will have the running gear removed and blocked up on cement piers. They don't have any cooking facilities as the camp will have an Amenities building to include dining and laundry services. Each structure will contain (1) 6000 watt water heater. Individual rooms will each have one Small app. branch circuit, (1) general lighting & receptacle circuit and (1) 3500 watt PTAC. There will also be one 120vac 20 amp circuit for plumbing heat tape beneath each unit. It appears that the manufacture used the Optional single family dwelling program for calculations as they have facilities listed on their calc. sheet for a general dwelling's use, ie; Dishwasher, range and dryer, but have fudged the numbers to bypass these values. They added all the above noted loads and included 3 w per sq. ft. for General lighting, took 100% of the first 10,000, then 40% of the rest. For a 6 room unit, they came up with a minimum service size of 96.49 amps and are installing panels with 100 amp mains to each structure. All this being said, my primary concerns are 1) What form of calculation for this type of structure should be employed?, and 2) Although the PTAC's can run individually/non-coincedental, in the harsh environments experienced in Montana winters combined with the "shift change" scenario of occupants all coming home at the same time, shouldn't these be calculated at a higher percentage? Units are single phase. Intend to feed from 120/208vac 3 phase MDP's. I appreciate any Pearls of Wisdom the members of this Forum may contribute.
has sent us their load calcs for the 3 models of units and their method in coming up with panel and feeders sizes has me concerned. To begin, these are 5 and 6 room 15' x 76' Manufactured structures, once in place will have the running gear removed and blocked up on cement piers. They don't have any cooking facilities as the camp will have an Amenities building to include dining and laundry services. Each structure will contain (1) 6000 watt water heater. Individual rooms will each have one Small app. branch circuit, (1) general lighting & receptacle circuit and (1) 3500 watt PTAC. There will also be one 120vac 20 amp circuit for plumbing heat tape beneath each unit. It appears that the manufacture used the Optional single family dwelling program for calculations as they have facilities listed on their calc. sheet for a general dwelling's use, ie; Dishwasher, range and dryer, but have fudged the numbers to bypass these values. They added all the above noted loads and included 3 w per sq. ft. for General lighting, took 100% of the first 10,000, then 40% of the rest. For a 6 room unit, they came up with a minimum service size of 96.49 amps and are installing panels with 100 amp mains to each structure. All this being said, my primary concerns are 1) What form of calculation for this type of structure should be employed?, and 2) Although the PTAC's can run individually/non-coincedental, in the harsh environments experienced in Montana winters combined with the "shift change" scenario of occupants all coming home at the same time, shouldn't these be calculated at a higher percentage? Units are single phase. Intend to feed from 120/208vac 3 phase MDP's. I appreciate any Pearls of Wisdom the members of this Forum may contribute.
