Customer has a 800a service, 208/120 3p. A fused disconnect from MDP with 225a fuses feeds a 225a A.T.S. A generator with a 225a CB feeds to the A.T.S. The A.T.S. feeds a 225a powerpanel[3p fused disconnects]. The loads are moters and air conditioning equipment and all are run continuesly. Sizing each at 125% of naneplate adds up to 220a. therefor it appears the panel is full. because these type of loads often draw less power than nameplate and we sized at 125% the load on the generator[and normal power] is half, just over 110a and the customer wants to move a existing load to the generator. Can i legaly do it? john
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Actual load
- Thread starter jociha
- Start date
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charlie tuna
Senior Member
- Location
- Florida
Re: Actual load
is this new load a life safety load? did you forget to add the smoke evac vent fans in your original concept?
is this new load a life safety load? did you forget to add the smoke evac vent fans in your original concept?
charlie tuna
Senior Member
- Location
- Florida
Re: Actual load
if the original panel feeds emergency power for protection of life safety (possible "smoke evacuation fans") then it must be considered an "emergency system". since the additional load is not an "emergency system" load i don't think it can be connected. it has been practiced in the past to add certain "critical" loads to "emergency systems", a prime example is ups computer loads, then find out that the generator is overloaded. that was why the code was changed to prevent this from occurring. we were contracted to perform a load test on a large office building's generator system. some of the leasing agreements included providing emergency power to tenant computer equipment and a.c equipment. the management group could see that the single 1000 kw generator was only loaded to 50 per cent when there was a power outage. they continued to add loads to the system. we found that actual connected load was over 1400 kw. they never included the life safety smoke exhaust fans in their calculations since the fire alarm system was never actuated during their power outages. when we gave them the load calculations they questioned them --- so they set up a test on a weekend. we shutdown the normal power -- the generator came on and transfered - we then pulled a fire alarm pull station - which called for the start of the smoke fans -- and the generator's output breaker tripped!!!! they had to add a second generator and run a riser up through the building to pick up all those "none emergency" loads!!!
if the original panel feeds emergency power for protection of life safety (possible "smoke evacuation fans") then it must be considered an "emergency system". since the additional load is not an "emergency system" load i don't think it can be connected. it has been practiced in the past to add certain "critical" loads to "emergency systems", a prime example is ups computer loads, then find out that the generator is overloaded. that was why the code was changed to prevent this from occurring. we were contracted to perform a load test on a large office building's generator system. some of the leasing agreements included providing emergency power to tenant computer equipment and a.c equipment. the management group could see that the single 1000 kw generator was only loaded to 50 per cent when there was a power outage. they continued to add loads to the system. we found that actual connected load was over 1400 kw. they never included the life safety smoke exhaust fans in their calculations since the fire alarm system was never actuated during their power outages. when we gave them the load calculations they questioned them --- so they set up a test on a weekend. we shutdown the normal power -- the generator came on and transfered - we then pulled a fire alarm pull station - which called for the start of the smoke fans -- and the generator's output breaker tripped!!!! they had to add a second generator and run a riser up through the building to pick up all those "none emergency" loads!!!
jtester
Senior Member
- Location
- Las Cruces N.M.
Re: Actual load
jociha
Refer to 220.35. It offers a way to measure load in an existing facility, and determine available spare capacity, if any.
Jim T
jociha
Refer to 220.35. It offers a way to measure load in an existing facility, and determine available spare capacity, if any.
Jim T
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