We have 6 new pieces of equipment coming in soon that each require 200A services at 480, 3phase. We have a 800amp OCPD on a GE spectra series panelboard existing that has paralleled 500mcm feeders in thhn. These feeders should be good for 760A at 75C. So everything looks good there. I am just unsure as to what loading factor is applied to these panelboards. IE can you only run 3 breakers at 200amps off this panelboard by adding the values of each breaker or is there some other factor that is allowed to run more breakers or maybe even all 6 200Amp breakers off this existing panelboard?
Panelboard Loading for new installation
- Thread starter User2
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The answer to your question is called a load calculation, and it's cover in Article 220.
The short of it is, your calculated load, with continuous load portion factored at 125%, must not exceed the panelboard OCPD rating or its supply conductors ampacity, whichever is the lesser of the two.
It is very common for the sum of load breaker ratings to exceed the main OCPD rating and the supply conductors ampacity.
Do your new pieces of equipment have nameplate data regarding the electrical supply?
The short of it is, your calculated load, with continuous load portion factored at 125%, must not exceed the panelboard OCPD rating or its supply conductors ampacity, whichever is the lesser of the two.
It is very common for the sum of load breaker ratings to exceed the main OCPD rating and the supply conductors ampacity.
Do your new pieces of equipment have nameplate data regarding the electrical supply?
ron
Senior Member
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- New York, 40.7514,-73.9925
Just because it gets a 200A feeder, doesn't mean the load is 200A. As suggested, you will need the actual load / nameplate to do a calculation.
zbang
Senior Member
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- Roughly 5346 miles from Earls Court
To be picky, I'm sure you mean circuits there, or maybe feeders, but not services. The word Service has a special meaning to the NEC (see article 100 - definitions).
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