i have an existing 800 amp 3 phase 120/208v incoming service feeding a main lug mdp which contains 1 400 amp breaker and 2 200amp breakers.i need to increase 1 of the 200 amp breakers to a 400 amp by doing this i will have exceeded the 800amp rating of the service my question is do i need to install an 800amp main breaker if i increase one of the 200 amp bkrs to a 400.
800 amp service
- Thread starter johneymac
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mcclary's electrical
Senior Member
- Location
- VA
Without knowing what size wire you have, we can't tell you if changing from a 200 to a 400 will push the service over it's capacity. If it's a true 800 amp service, it probably will not, but without load calc, and knowing what you have now, it's impossible to answer. But you're under your 6 throw rule so you still don't need a main
HotConductor
Senior Member
- Location
- Philadelphia
If it's a metered service you should be able to call the POCO and find out the highest load of the existing service for the past twelve months. Then just add in your new loads.
A good point by Mc...is it a true 800 amp service or is it an 800 amp rated mdp??? What size SE conductors, cu or al or how many parallels?
Here is a good article for commercial load calcs:
http://ecmweb.com/mag/electric_commercial_load_calculations/
A good point by Mc...is it a true 800 amp service or is it an 800 amp rated mdp??? What size SE conductors, cu or al or how many parallels?
Here is a good article for commercial load calcs:
http://ecmweb.com/mag/electric_commercial_load_calculations/
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