Janet W. in Spokane here. I've got a weird situation with a multi-tenant office building where Avista Energy has the main meter correct but the sub-meters for individual tenants seem to have wrong multipliers. The total of all sub-meters is reading 40% higher than the main utility meter. Has anyone dealt with sub-metering multiplier errors before?
Sub-metering Multiplier Issues in Multi-Tenant Building
Theresa K. from Bozeman - Janet, are these utility-owned sub-meters or customer-owned? NorthWestern Energy uses different CT ratios for sub-meters sometimes and the programming can get mixed up. I had a case where they used 200:1 CTs but programmed 100:1 multipliers on half the sub-meters.
Theresa - these are Avista-owned sub-meters, all installed at the same time last year. Each tenant is getting billed separately but when I add up all their usage it's way more than the main meter shows. Something is definitely wrong with the calculations.
Gail P. in Missoula here - I've seen this with NorthWestern where they copy the main meter's CT ratio to all sub-meters even though the sub-meters have different CTs. Could be they programmed all your sub-meters with the same multiplier when they should be different ratios.
Randy Dawson here. Janet, sub-metering multiplier errors are becoming more common as utilities install more AMI systems in multi-tenant buildings. The problem is often that technicians copy settings from one meter to another without verifying the actual CT ratios. You need to physically verify each sub-meter's CT ratios and compare to the billing multipliers. Also check if estimated readings on any sub-meters are masking the problem - if one sub-meter has been estimated for months, the error might be worse than it appears. Request actual readings for all meters for the same billing periods.
Vince S. from Hartford - Randy's right about estimated reads masking problems. Eversource had our sub-meters estimated for 6 months while the main meter was actual reads. When they finally got actual readings from all meters, we discovered massive overbilling on Schedule GS-1 accounts.
Good point about estimated reads Vince. I'm going to request 12 months of actual vs estimated reading flags for all meters. This building has 8 sub-meters and if some were estimated while others weren't, that could explain the discrepancy. Will report back what I find.
Tamara E. from Chattanooga here. Janet, also verify that all your sub-meters are on the same rate schedule. EPB had some of our sub-meters on Schedule GSA and others on Schedule GSB with different demand calculations. Made the billing totals look wrong even though multipliers were correct.
Kevin N. in Mobile - following this thread. Alabama Power is installing sub-meters in our building next month and I want to avoid these issues. Janet, did you ever get resolution on your multiplier problems?
Kevin - finally got it resolved! Turned out 5 of the 8 sub-meters had CTs programmed wrong. Avista admitted the installation crew used copy-paste settings instead of verifying each CT ratio. Getting refunds totaling $28,000 across all affected tenants. The key was Randy's advice to verify every CT nameplate physically.