Should I use the lamp rating or the measured draw?

The measured draw, at the panel, whenever you can get it. The lamp rating leaves out power-supply losses, the exhaust blower, and any chiller: on a water-cooled system those can add a third or more to the load. A clamp meter on the supply for one shift settles it and is worth more than any assumption this page could offer.

Why energized hours rather than curing hours?

Because a mercury lamp draws its full load whether or not parts are underneath it. Shuttering blocks the light, not the power. And lamps are usually left struck through breaks and changeovers precisely because restriking shortens lamp life and needs a warm-up before the system is usable again, so the energized figure is normally well above the curing one.

How do I compare this to a UV LED array?

On cost per part, and only when both systems are delivering the dose the material needs at the same line speed. Comparing installed kilowatts is meaningless. The two technologies deliver very different fractions of their input power as usable UV in the band a given photoinitiator absorbs. Comparing shift cost is worse, because it rewards whichever system happened to be assumed to run fewer hours.

Is the annual figure trustworthy?

It is arithmetic on a stated convention: 250 shifts, which is an ordinary single-shift working year. Double it for two shifts, scale it for a seasonal plant, and replace it outright for a continuous operation. It is offered because the payback page needs an annual number and, in the earlier version, gave the reader no way at all to produce one.

Does the heat a lamp throws off cost extra?

In a conditioned space, yes, and it does not appear on this page. Most of a mercury lamp's input power leaves as heat, and any part of it that reaches the room has to be removed again by the building's cooling. The heat-load and cooling pages price that; this one prices only the electricity going into the system.

Is UV energy usually a significant cost?

Usually not, and it is worth saying so. Under a cent a part is common, which puts it far below material, labour and scrap for most products. The exceptions are high-volume low-value parts, plants on expensive tariffs, and lines with poor utilisation. The last being the one this page makes visible, because a time-priced process gets steadily worse as throughput falls.

UV Curing calculator

Mercury UV Lamp Energy Cost Calculator: Cost per Part

Price the electricity a mercury UV curing system consumes, in the form that can actually be used. Enter the system's electrical draw while the lamp is struck, the energized hours per shift, your blended electricity rate, and the parts that came out of the tunnel. The calculator returns the cost per part first, then the per-shift, annual and hourly figures behind it. Cost per part is the headline because it is the only one that survives a change in shift length or production rate, and the only one on which a mercury system and a UV LED array can honestly be compared.

What this calculator does

Turn a mercury UV system's electrical draw and runtime into the energy cost per part, per shift and per year. The form the number has to be in before it can be compared to anything.
Use it for establishing the energy line in a per-part cost model, producing the annual figure a UV LED retrofit case needs, showing what low utilisation does to the cost of a time-priced process, comparing two curing systems on a common basis, sizing the energy share of a quoted price on a new job.
Turn a mercury UV system's electrical draw and runtime into the energy cost per part, per shift and per year. The form the number has to be in before it can be compared to anything.

Formula used

Energy used per shift (kWh) = system draw × energized hours
Shift energy cost = energy used per shift × electricity rate
Energy cost per part = shift energy cost ÷ parts cured per shift
Hourly energy cost = system draw × electricity rate
Annual energy cost = shift energy cost × 250 shifts (a disclosed convention: substitute your own year)

Inputs explained

UV system electrical draw (energized): Total electrical load while the lamp is struck. Include power-supply losses and the exhaust blower, and the chiller on a water-cooled system: the lamp's nameplate rating alone is not the system's draw.
Energized hours per shift: Hours the lamp is struck, not hours it is curing. A shuttered mercury lamp draws full power, and it is normally left running because restriking costs lamp life and a warm-up.
Blended electricity rate: All-in rate including demand charges and delivery, not the energy-only headline rate.
Parts cured per shift: Good parts through the tunnel in that same shift. This is what converts a utility bill into a number that can be compared with another process.

How to use the result

Best suited to establishing the energy line in a per-part cost model, producing the annual figure a UV LED retrofit case needs, showing what low utilisation does to the cost of a time-priced process, comparing two curing systems on a common basis, sizing the energy share of a quoted price on a new job.
Energy is one line of a UV system's cost. Lamps, labour, downtime, scrap and cooling belong to other pages, and energy is rarely the largest of them. Assumes a constant draw. Systems with power-level control, standby modes or multiple lamps that cycle will differ. Ignores the cooling load a mercury lamp adds to the building's air conditioning, which is a real cost in a conditioned space and is priced on the heat-load page. Says nothing about whether the dose delivered is correct. A system consuming exactly this much electricity can be undercuring. Comparisons to LED are only valid at equal dose and equal throughput; this page cannot check that for you.

Current U.S. benchmarks

As of May 2026, industrial electricity averages 8.7 cents per kWh across the U.S. (EIA), up 5.1% from a year earlier. State averages range widely, so plants should confirm against their own tariff.

Common questions

Should I use the lamp rating or the measured draw? The measured draw, at the panel, whenever you can get it. The lamp rating leaves out power-supply losses, the exhaust blower, and any chiller: on a water-cooled system those can add a third or more to the load. A clamp meter on the supply for one shift settles it and is worth more than any assumption this page could offer.
Why energized hours rather than curing hours? Because a mercury lamp draws its full load whether or not parts are underneath it. Shuttering blocks the light, not the power. And lamps are usually left struck through breaks and changeovers precisely because restriking shortens lamp life and needs a warm-up before the system is usable again, so the energized figure is normally well above the curing one.
How do I compare this to a UV LED array? On cost per part, and only when both systems are delivering the dose the material needs at the same line speed. Comparing installed kilowatts is meaningless. The two technologies deliver very different fractions of their input power as usable UV in the band a given photoinitiator absorbs. Comparing shift cost is worse, because it rewards whichever system happened to be assumed to run fewer hours.
Is the annual figure trustworthy? It is arithmetic on a stated convention: 250 shifts, which is an ordinary single-shift working year. Double it for two shifts, scale it for a seasonal plant, and replace it outright for a continuous operation. It is offered because the payback page needs an annual number and, in the earlier version, gave the reader no way at all to produce one.
Does the heat a lamp throws off cost extra? In a conditioned space, yes, and it does not appear on this page. Most of a mercury lamp's input power leaves as heat, and any part of it that reaches the room has to be removed again by the building's cooling. The heat-load and cooling pages price that; this one prices only the electricity going into the system.

Last reviewed 2026-08-25.