kwired
Electron manager
- Location
- NE Nebraska
As already mentioned, you need to inform the POCO about the expected load change. They generally could care less what you have for overcurrent protection.
I have a school building I am upgrading service to. Existing was 2000 amps single phase for a main. Transformer supplying it - 100kVA. Load history showed it seldom went much higher then 80 kVA. - that is only about 333 amps.
I am upgrading to 208/120 system and 1200 amp main - adding mostly HVAC loads, replacing some existing HVAC though so load calculation is a little complex. But I figured at least 400 amp main is probably enough to handle the HVAC load and 600 amp main probably guarantees a little assurance that we safely handle the total load - but I am putting in 1200 amp anyway because it is relatively easy for POCO to swap the transformer compared to me replacing 600 amp gear with 800 or 1200 down the road should more load be added, and really isn't going to cost much more then a 600 amp supply in this case. BTW 600 amp is about 432 kVA - POCO is going to provide a 225kVA transformer - still well short of if that 1200 amp main were fully loaded. POCO charges to provide the 225 is also less then it is to provide.
In some cases if you demand to have larger supply but don't use it's capacity - it will cost you more in demand charges then if you subscribe to a lesser service. This usually applies to larger power users - often you need to have a demand of over 100-200 kVA before those charges kick in. If you have a high demand service the POCO needs to be able to supply that demand, that usually comes with higher monthly minimum charges, but possibly a lower overall rate per kW. If you don't use the high kW though you usually end up in a situation where you would have spent less on a lower usage agreement - but would have lower rated supply transformer and demand penalties if you do have periods of high usage.
