Better check and see if there are any special requirements from the owner or engineer. That kind of occupancy often has special need for high intensity lighting areas. Also, will the booth be supplied as a wired unit? If so, get its exact requirements. They usually have big fans and lots of lighting.
This is a body shop that is open already and in need of a larger service...currently 120/240 single phase 200amp.
So...3300sq ft x 3va per ft = 9900va Spray booth 45 amps x 240v =10800va Air compressor with two 5 hp motors, 28amp each x 2 =56amp x 240v = 13440va Welder nameplate = 7700va Well water pump 7.5 amp x 240 volt= 1800va Electric water heater 12 amp x 120v = 1440va Office electric heat = 4000va Spray booth lighting = 1560va Outside HPS wall packs = 1200va Office equipment etc. =1200va Waste oil fired heaters =2400va 20 shop 120volt recp outlets, 20x180va=3600va Sign circuit = 1200va
60240 divided by 240 volt =251 amps
I want to install a new service with a 400 amp panelboard with main, fed by 2 service entrance conductors 500mcm copper and a reduced neutral at 350 mcm copper in 3inch IMC to a 320 single phase meter can.I'll use pvc between the meter can and the panelboard to avoid bonding requirements.From the new panelboard I'll backfeed an exsisting 100amp sub panel and also refeed all exsisting circuits that originated from the 200amp main loadcenter from the new 400 amp panelboard.My GEC will be 1/0 copper to waterpipe with 2 supplemental ground rods.
If you run your service entry conductors from multi barreled lugs on the load side of the meter to one two hundred ampere enclosed breaker or disconnect to feed the two hundred ampere panel and a one hundred ampere enclosed breaker or disconnect to feed the one hundred ampere panel you will save money over the high cost of a four hundred ampere main breaker panel. -- Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
Tom...thanx for the replie...with a load of 251 amps now a 200/100 amp setup as you described wouldn't leave much room for any more equipment at the shop. The owner wants 400 amps in case of future needs.Due to the location of the panels that exsist in the building,it is not feasible to install seperate disconnects.The wiring in the two exsisting panels is a mess to say the least.Guys adding and adding circuits over the years without properly figuring the load and causing a dangerous situation in my opinion.I will relocate some of the heavy loads to the new 400 amp Panelboard...like the spray booth and the air compressor which is drawing off the 100 amp sub panel.
I did consider the type of installation you mentioned.That is what we do around here for residential 400 amp services...with dual barrel lugs and two 200 amp main breaker panels.We also feed the 320 meter with dual 4/0 URD in a 4inch PVC from the POCO manhole.