malachi constant
Senior Member
- Location
- Minneapolis
Engineer here. Trying to figure out how far to enforce the load balancing specifications. Spec requires loads to be tested and balanced on all equipment - transformers, switchboards, panelboards. Spec says if any two phases within a panelboard are not balanced within 20% then rebalance/retest.
After initial testing the worst one is 22.3A/18.4A/18.0A. 22.3/18.0 = 124% -> a 24% difference. This is a 480V lighting panelboard. Contractor is arguing that within smaller panelboards a couple phases being off by 20% is not a big deal.
So what are the ramifications of an unbalanced panel? What about an unbalanced transformer? Service? At what point is balancing a concern, and why?
After initial testing the worst one is 22.3A/18.4A/18.0A. 22.3/18.0 = 124% -> a 24% difference. This is a 480V lighting panelboard. Contractor is arguing that within smaller panelboards a couple phases being off by 20% is not a big deal.
So what are the ramifications of an unbalanced panel? What about an unbalanced transformer? Service? At what point is balancing a concern, and why?