Frank M from Pittsburgh, PA. Duquesne Light territory. Found something I have never seen before. My client is a machine shop with two accounts at the same address — one for the shop floor and one for the office/warehouse. When I lined up the billing periods for both accounts, I noticed a 6-day overlap in February. The shop meter was read on Feb 18 and the bill covers Jan 20 - Feb 18. The office meter was read on Feb 24 and that bill covers Feb 12 - Feb 24. But wait — the previous office bill ended on Feb 12 and the previous shop bill ended on Jan 20. So far so good. The problem is the office bill for Dec 15 - Feb 12 is a 59-day bill. Then the next office bill is Feb 12 - Feb 24, only 12 days. And the shop bill covers Jan 20 - Feb 18. None of this lines up and when I map it out, the 6 days from Feb 12-18 appear to be billed on BOTH the office account and the shop account.
Client billed twice for the same 6 days — overlapping billing periods
Frank, overlapping billing periods on co-located accounts usually indicate a meter reading scheduling error. When two meters at the same address are on different read routes, the billing periods can drift apart. That should not cause double billing though — each meter measures its own circuit. Unless the meters are cross-wired and measuring the same load on overlapping days. Have you verified the meters are measuring separate circuits?
I had a similar situation in Duquesne territory. Two meters at the same service address, different read dates. The problem turned out to be that the billing system was allocating common area usage to both accounts during the overlap days. The building had a third circuit for parking lot lighting that was supposed to be on the office meter but was accidentally split across both meters during a panel reconfiguration. Not exactly double billing but the common load was counted twice.
Walt, that is an interesting theory. This building does have a common air compressor system that serves both the shop and the office warehouse. Let me check whether the compressor circuit is metered correctly.
Checked the panel. The air compressor is on a 100-amp breaker that feeds through the shop meter. But there is a sub-panel in the warehouse that also has a 60-amp feed from the office meter going to a second compressor. Both compressors serve the same air header. So the compressed air system is split across both meters, which is correct if both compressors are actually on separate circuits. But here is what I found — the 60-amp feed from the office meter was back-feeding through the air header isolation switch into the shop meter circuit during certain operating conditions. Essentially one compressor was pushing load onto the other meter through the shared piping and controls.
Frank, that is not a billing error — that is an electrical installation issue. A back-feed through shared controls means the shop meter is measuring some of the office compressor load and vice versa. The billing periods overlapping just made it visible in the data. The real fix is electrical, not billing.
Ray, you are right that the root cause is electrical. But the billing impact is real. During the 6-day overlap period, the back-feed caused the shop meter to register about 1,800 kWh of load that was already measured by the office meter. My client paid for those 1,800 kWh twice. At the commercial rate that is about $180. Small amount for those 6 days, but if this back-feed has been happening continuously, the double-metering adds up over time.
Frank, to quantify the ongoing impact you would need to compare the combined consumption of both meters against what the building should be using based on equipment nameplate ratings and operating hours. If the combined metered total exceeds the calculated load, the difference is the back-feed double counting.
Did that analysis. Combined metered consumption averages 48,200 kWh/month. Calculated load based on equipment inventory is approximately 44,500 kWh/month. The 3,700 kWh/month difference — about 8% — is likely the back-feed double counting. At $0.095/kWh that is roughly $350/month or $4,200/year.
So you found $4,200/year in double-metered consumption caused by an electrical cross-feed. The question is who pays for the correction — the utility or the customer. The wiring behind the meter is typically customer responsibility. But the utility has an obligation to ensure meters accurately measure only their assigned circuits. I would argue shared responsibility.
Filed with Duquesne Light. They sent an engineer who confirmed the back-feed issue. DL agreed it was a metering accuracy problem and credited 12 months of estimated double-metered consumption — $4,100. They also required the client to hire an electrician to install an isolation device preventing future back-feed. Electrician cost was $800. Net benefit to client: $3,300 plus the ongoing $350/month savings once the isolation device was installed. Not a huge case but a genuinely unusual finding.
Great detective work Frank. I never would have thought to check for electrical back-feed between co-located meters. Adding this to my audit checklist for any client with multiple meters at the same address.