Custom fabrication shop in Charleston SC. Dominion Energy. Six welding stations, each draws 40-80 kW depending on the process. Normally 2-3 stations active at any time for about 150-200 kW demand. But when they have a rush job all six stations run simultaneously and demand spikes to 420 kW. Those spikes happen maybe 3-4 times per year but they set the ratchet for the following 11 months. Annual demand overcharge from occasional spikes estimated at $18,000.
Welding shop demand ? intermittent heavy loads
Ralph ? welding shops are one of the hardest demand profiles to manage because the spikes are operational necessities, not waste. You cant tell a fabricator not to run all six stations when a deadline demands it. But you CAN install a demand controller that monitors total shop demand and alerts the foreman when theyre approaching the ratchet threshold. A visual or audible alarm at 350 kW gives the foreman a choice: accept the spike or stagger the work.
Thomas ? a demand alarm is a practical middle ground. The foreman can make an informed operational decision rather than unknowingly spiking demand. The cost difference between staying at 350 kW and hitting 420 kW for one interval is roughly $1,500 in ratcheted charges over the following year. If the foreman knows that, they might choose to stagger the work by 15 minutes.
Similar situation at a steel fabrication shop in Birmingham. We installed demand monitoring with a traffic light display visible from the shop floor. Green below 300 kW, yellow at 300-380 kW, red above 380 kW. The welders self-manage ? when the light goes yellow they coordinate. Demand spikes decreased from 6 per year to 1. Annual demand charge savings of about $12,000 for a $3,500 monitoring installation.
Installed the traffic light demand monitor. After 4 months the shop has not exceeded the yellow threshold even once. The welders treat it like a game ? keeping the light green is a point of pride. Actual demand reduction compared to same period last year: average 65 kW lower peak. Annual projected savings: $9,600. Client spent $3,800 on the monitoring system. Best ROI of any recommendation Ive made this year.
Terrific example of behavioral demand management. The traffic light monitoring approach works because it provides real-time feedback without restricting operations. The workers retain control of the decision which eliminates the resistance that automated load shedding creates. Ralphs initial identification of the spike pattern, Thomas suggestion of demand alerting, and Terrences traffic light implementation represent the kind of practical, low-cost demand reduction that auditors should recommend. Not every demand problem requires expensive equipment.
The traffic light approach is brilliant in its simplicity. From the utility side we always recommended expensive automated load shedding systems. A $3,500 visual indicator that lets the workers self-manage is far more practical for small fabrication shops. The workers understand the financial impact and cooperate voluntarily. Much better than an automated system that interrupts their work without warning.