Why This Matters on a Plant Floor
A failed metal halide ballast at 3 am in a factory handling night-shift picking leaves the warehouse dark until the next working day. A second failure within 5–8 years means a second emergency replacement and a second production delay. For a 100-metre warehouse relying on night shifts, every downtime hour costs money, and every ballast replacement is an unplanned expense.
Metal halide high bays are cheaper to install, so the initial capex is lower. But by year three, ballast failures and rapid lumen loss force a choice: pay for maintenance and accept dim light, or retrofit to LED. By year five, the retrofit often looks inevitable. LED high bays cost more upfront but usually pay that back within a few years through lower energy bills and far less maintenance. For purchase teams, the question is not which is cheaper today, but which costs less to own.
In humid coastal environments like the south Gujarat and Daman belt, temperature swings and salt air accelerate ballast capacitor failure. LED systems, with no ballast and instant-on operation, prove more reliable in these conditions.
Light Output and Efficacy: Why Lumens Fade
A 400 W metal halide system, measured at the fixture output, delivers 70–80 lumens per watt including ballast losses. A 150 W LED high bay delivers 130–190 lumens per watt. That gap, together with metal halide's lumen loss described below, is why a 150 W LED is the usual swap for a 400 W metal halide fitting in service, drawing 67% less electricity. Check the LED's lumen output on its datasheet against the lux you need.
But there is a catch in metal halide: lumen depreciation. Within the first six months, output falls by 20% or more. By mid-life, around 7,500–10,000 hours of operation, a metal halide fixture has already lost 50% of its initial lumens. It is still drawing 400 W. The plant operator is paying for full power while receiving half the light.
Metal halide fixtures also lose 15–30% of bare-bulb output through reflector and fixture inefficiencies. A bare bulb rated at 50,000 lumens becomes 35,000–42,500 lumens at the work surface.
LED high bays maintain 70% of initial output (L70 rating) across their entire 50,000–100,000 hour lifespan. This consistency means the light at year five is still predictable and adequate. No surprise dimming. No mid-life rework to the lighting design.
Lifespan and Maintenance Cycles
Metal halide bulbs carry a rated life of 15,000–20,000 hours under ideal ballast conditions. At 16 hours a day, 300 days a year, a fitting runs about 4,800 hours a year, so a 15,000–20,000 hour lamp lasts roughly three to four years on paper. In reality, ballast quality and voltage stability cut that short.
The real maintenance burden lies with the ballast, not the bulb. Metal halide ballast capacitors fail around 3–3.5 years. Full ballast replacement cycles occur every 5–8 years in high-use settings. Each replacement requires an electrician, downtime, and parts.
LED high bays contain no ballast. The driver is solid-state and integrated into the fixture. Driver failure rates are substantially lower than HID ballast failure rates. When a driver does fail, it is replaced as a single unit, not a separate component. A typical LED high bay lasts 50,000–100,000 hours. At 16 hours per day, that is 8.6–17 years of operation with no maintenance beyond cleaning.
| Attribute | Metal Halide 400 W | LED High Bay 150 W |
|---|---|---|
| Efficacy (lumens per watt) | 70–80 (including ballast loss) | 130–190 |
| Warm-up time | 15–20 minutes | Instant-on |
| Restrike delay | 5–15 minutes | None |
| Rated life (hours) | 15,000–20,000 | 50,000–100,000 |
| L70 point (70% output retention) | Not applicable; L50 ~7,500–10,000 hours | 50,000–100,000 hours |
| Ballast life | Capacitor failure 3–3.5 years; replacement cycle 5–8 years | Integrated driver; no separate ballast replacement |
| Occupancy sensor compatible | No (warm-up and restrike prevent use) | Yes (instant-on, fully compatible) |
Energy Consumption and Annual Costs
A 400 W metal halide fixture draws approximately 455 W when ballast losses are included. Replacing it with a 150 W LED cuts the input power by 67%. The energy saving is 305 W per fixture.
In a warehouse running 16 hours per day, 300 days per year (typical for shift-based logistics), a single fixture consumes:
- Metal halide: 455 W × 16 hours × 300 days = 2,184 kWh per year
- LED: 150 W × 16 hours × 300 days = 720 kWh per year
- Annual energy saving per fixture: 1,464 kWh
At industrial tariffs typical for the south Gujarat belt, this represents substantial annual savings. LED high bays also enable occupancy sensor integration. A motion sensor can switch LEDs off when the aisle is unoccupied, delivering an additional 20–40% energy saving. Metal halide cannot be used with motion sensors because of 5–15 minute restrike delay. The fixture would not reach full brightness before the sensor switched it off again.
Maintenance, Ballast Failure and Downtime
Metal halide ballast failure is not rare and not a manufacturing defect; it is a normal wear cycle. After 3–3.5 years, capacitors in the ballast begin to fail. A failed capacitor causes the ballast to hum, overheat, or stop firing the bulb altogether. The replacement ballast must match the lamp type and rating of the original; check the lamp's datasheet. Compatibility errors are common in rushed replacements.
A ballast replacement means the part, an electrician's call-out, and the downtime. In a 24/7 warehouse, downtime during a power failure or urgent ballast swap can halt operations. With 20 fittings on a 5 to 8 year ballast cycle, every fitting needs at least one new ballast in a decade, and many need two.
LED fixtures eliminate this maintenance category. There is no ballast to fail. The driver is integrated and solid-state. Cleaning the fixture and replacing a failed driver (rare) are the only tasks. A failed driver is a fixture-level replacement, not a component swap, so compatibility errors disappear.
Payback Calculation for a Typical Warehouse Retrofit
A 100-metre warehouse with 20 high bay fixtures currently using 400 W metal halide proposes a retrofit to 150 W LED.
Annual energy saving: 20 fixtures × 1,464 kWh = 29,280 kWh per year, at 16 hours a day and 300 days a year. Multiply by your tariff per unit to put a figure on it.
Annual maintenance saving: no ballast replacements. With every fitting needing one or two ballasts a decade, that is roughly 2 to 4 ballast jobs a year avoided across the 20 fittings, each with its part, call-out and downtime.
Payback period, in years = extra cost of the 20 LED fittings, installed ÷ (29,280 kWh × your tariff per unit + the cost of the ballast jobs avoided each year). At industrial tariffs in the belt, the energy saving alone usually recovers the extra cost of an LED high bay within a few years; work it through with your actual fitting prices and tariff.
At 12 hours a day instead of 16, the energy saving falls by a quarter, to about 21,960 kWh a year, and the payback stretches by about a third.
These figures are indicative, based on the assumptions stated. Confirm them against the manufacturer's current datasheet and your site conditions with a licensed electrical engineer.
Standards and Compliance
High bay lighting fixtures must comply with safety and performance standards. The standards to refer to are IS 10322 (Luminaires), IEC 60598 (Luminaires) and IEC 60529 (Degrees of protection provided by enclosures, particularly important for dust and humidity in warehouse environments).
Refer to the current edition of IS 10322 and IEC 60598, and confirm your fixture selection with your licensed electrical contractor for local installation codes and voltage stability.
What We Stock
We are authorised channel partners for Bajaj Electricals and Havells, whose ranges include LED high bays and industrial and area lighting for warehouse and factory use. Our Vimal Electric Corporation branch in Silvassa supplies industrial lighting and controls for the plant belt.
For retrofit or new installation specifications, send your warehouse load list or single-line diagram to our enquiry form. We will confirm availability and lead time for your region.