UV Curing calculator

Mercury UV Lamp Energy Cost Calculator

Unlike LED arrays, mercury arc lamps cannot cycle on demand — they must stay on between parts and during breaks, often for the whole production shift. That idle energy hits the utility bill whether parts are moving or not. This calculator reflects that reality: enter the lamp's energized kW, the shift hours it stays on (not just the time parts are under it), the all-in $/kWh, and the parts cured to land on a shift cost and a per-part energy cost.

What this calculator does

  • Cost out a mercury arc UV lamp per shift and per part — including the always-on idle period mercury lamps need between jobs.
  • Use it to baseline a mercury cure line before evaluating an LED retrofit, or to put energy on a job quote when mercury cure is the bottleneck.
  • Returns shift energy cost and energy cost per cured part for a mercury arc UV lamp, including the unavoidable idle-on energy.

Formula used

  • Energy used (kWh) = lamp electrical draw × energized hours
  • Shift energy cost = energy used × $/kWh
  • Energy cost per part = shift energy cost ÷ parts cured

Inputs explained

  • Lamp electrical draw (energized): Total kW while the lamp is struck — same in production and idle. Mercury lamps cannot dim usefully.
  • Energized hours per shift: Total hours the lamp is on, including warm-up, idle between parts, and breaks. Often = full shift length.
  • Blended electricity rate: All-in industrial rate including demand charges allocated across kWh.
  • Parts cured per shift: Good cured units only — exclude scrap so per-part cost is honest.

How to use the result

  • Use to baseline a mercury cure line before any LED retrofit decision, in energy reporting, and when energy is a meaningful share of cost on a quote (high-volume or 24/7 operations).
  • Covers the lamp itself. Excludes ballast losses (often 5–15% on top), cooling water chillers, exhaust ozone scrubbing, and any compressed air. Mercury lamps also have warm-up and re-strike cycles that consume energy without producing cure — count those minutes in 'energized hours' for an honest number.

Common questions

  • Why am I paying for the idle hours? Mercury arc lamps need to stay struck (lit) to maintain spectral output. A cold-restrike costs 5–15 minutes of warm-up and shortens lamp life, so production lines just leave them on between parts and over breaks. That idle electricity is real cost — it is what makes the LED switch attractive on the energy line.
  • Is the ballast loss already in the lamp kW? Usually no. Lamp data sheets quote the arc kW; the magnetic or electronic ballast adds 5–15%. If you can, measure with a clamp meter at the panel feed (which catches everything); otherwise multiply lamp kW by 1.10 as a defensible default.
  • What does an LED conversion typically save? On a similar dose-at-part basis, LED energy is often 40–70% lower because LEDs (a) only need to be on when parts are present and (b) put a higher fraction of input power into the useful UV band. Run this calculator with your mercury numbers, then UV LED Energy Cost with retrofit numbers, and the delta drives the UV LED Payback model.
  • Does this include cooling water? No — chiller and pump loads are separate utilities. On large mercury systems, chiller energy can be 15–30% of the headline lamp energy, so it matters. Add a separate utilities cost line for chillers and exhaust if the goal is total cost of ownership.

Last reviewed 2026-05-12.