A high mast retrofit replaces 1000 W and 2000 W HID heads with LED heads of roughly a third of the wattage, and it usually pays for itself twice. Once on the electricity bill. Once on the crane hire that stops being an annual event.
That second saving is the one that makes high mast different from every other retrofit. A warehouse high bay that fails is a ladder job. A mast head that fails at 35 metres is a lift, a permit, a traffic management plan, and a shift that the yard cannot run at full capacity. When the fixtures behind that cost stop failing, the economics of the whole asset change.
Which is exactly why a lazy retrofit hurts so much here. Swap in the wrong heads and you have bought yourself another decade of the same crane bookings, on a taller ladder.
This guide runs the conversion in the order that survives contact with a real site.
Key Takeaways
- Realistic equivalents: 1000 W HID head to 300-400 W LED, 1500 W to 400-600 W, 2000 W to 600-800 W. Count ballast watts in the legacy figure, not the lamp rating.
- Decide one-for-one versus redesign before ordering. Directional LED optics frequently hold the same lux with fewer heads per mast, which cuts connected load twice.
- Weight and wind area are structural inputs. A heavier head ring on a mast designed decades ago is an engineering check, not a detail.
- The lowering system is worth more than the efficacy difference between two candidate fixtures. If the winch does not work, budget a crane instead.
- Aiming is what makes or breaks the result. A retrofit commissioned without a photometric study produces a bright halo and a dark centre.
Why High Mast Retrofits Are Not High Bay Retrofits
Both swap HID for LED. Everything after that differs.
On a warehouse roof, the fixture is most of the cost, access is cheap, and a mistake is recoverable next week. On a mast, the fixture is a minority of the cost, access is expensive and scheduled, and a mistake sits in the air for years because nobody wants to book the lift twice.
That inverts the specification priorities:
- Reliability outranks efficacy. Two lm/W between candidate fixtures is noise next to one avoided crane visit.
- Serviceability outranks price. A head that needs the whole assembly replaced when a driver fails costs more over ten years than one with an accessible driver compartment.
- Aiming repeatability matters. Heads get taken down and put back. If the bracket does not hold a recorded angle, every service visit degrades the scheme.
- Surge protection is not optional. Masts are the tallest metal object in a flat yard, on long feeders. Transient damage, not LED wear, is what typically ends an outdoor fixture’s life. See surge protection.
Realistic Wattage Equivalents for Mast Heads
The most-asked retrofit question has a table for an answer. These are starting points for budget scoping, not a design.
| Legacy mast head | System watts with ballast | LED replacement | Typical LED output |
|---|---|---|---|
| 400 W metal halide | ≈ 455 W | 150-200 W | 24,000-32,000 lm |
| 1000 W metal halide | ≈ 1,080 W | 300-400 W | 48,000-64,000 lm |
| 1000 W HPS | ≈ 1,090 W | 300-400 W | 48,000-64,000 lm |
| 1500 W metal halide | ≈ 1,610 W | 400-600 W | 64,000-96,000 lm |
| 2000 W metal halide | ≈ 2,150 W | 600-800 W | 96,000-128,000 lm |
Two physical reasons the LED number lands so far below a naive lumen-for-lumen swap.
HID wastes most of its output inside the fixture. A discharge lamp radiates in every direction and depends on a reflector to redirect it. A large share never reaches the ground. LED optics emit toward the target from the start, so fewer lumens leave the fixture and more of them land where the design wanted them.
HID also depreciates fast, and the original design already compensated for it. A metal halide installation was specified with enough day-one output to still meet the target after heavy lumen decay. Sizing an LED replacement against the original lamp rating buys light that was never actually delivered in year three.
The practical consequence: quote against measured delivered lumens at your mounting height, not against the lamp label on the old head. That is what the IES file is for, and how to read one covers the four checks that expose a file worth doubting.
Step 1: Audit What Is Actually Up There
Drawings lie on masts more than anywhere else, because heads get changed one at a time over decades.
Record, per mast:
- Mast height, and the head count and type actually fitted. Count them from the ground with binoculars if no lowering system exists.
- Lamp rating and ballast type, including whether anyone has already fitted partial LED.
- How many heads are dead. A mast running four of eight heads is a different baseline from a healthy one, and using it as the “before” case overstates the retrofit gain.
- The lowering system, and whether it works. Winch, cable condition, ring, and whether anyone has operated it in the last two years.
- Existing aiming angles, photographed before anything comes down.
- Feeder and control arrangement. Circuit sizing, contactor or photocell control, and whether masts share circuits.
Point 3 deserves emphasis. Half the “before” measurements on retrofit proposals are taken on a partly failed installation, which makes any comparison flattering and useless.
Step 2: One-for-One, or Redesign
This decision changes the price of everything downstream, so make it deliberately.
One-for-one replacement keeps the head count and mounting positions, swapping each HID head for an LED head. It is fast, needs no structural recalculation if the weight is comparable, and preserves the existing aiming pattern. It is the right answer when the existing scheme genuinely performs and the objective is energy and maintenance.
A redesign recalculates the scheme from the target level and the current yard layout. It commonly reduces head count per mast, because directional optics deliver more usable light per watt than a reflector ever did. It can also reduce the mast count on an over-lit site, though that saving is rarely available on a retrofit budget.
Redesign earns its cost when any of these apply:
- The yard operation changed since the original design, which is normal in container terminals and logistics parks.
- The original scheme was never right, and the complaints predate the failures.
- Head count per mast is high enough that removing two heads per mast across a site pays for the study several times over.
- Light spill or glare complaints exist, since aiming is being redone anyway.
For the geometry behind either path, the high mast lighting guide covers heights, coverage radius and spacing.
Step 3: The Design Calculation
A high mast lighting design calculation answers one question: how many heads of what wattage and distribution, aimed how, hold the target level with acceptable uniformity across the actual area.
The inputs are unglamorous and all of them matter:
- Target maintained illuminance for the operation. Container stacking yards commonly run 20-50 lx, quay aprons 50-100 lx, interchange and highway areas per the applicable road class.
- The area geometry, including obstructions. An empty-yard model is the single most common source of disappointment. If containers stack six metres high, model them.
- Mast positions and heights as built, not as drawn.
- Real IES files for the exact head, optic and wattage being quoted.
- A maintenance factor of 0.7, not 0.8, for a dusty or salty outdoor site with long cleaning intervals.
The output is a fixture schedule plus an aiming table: tilt and rotation for every head on every mast. That aiming table is a deliverable, not a working note. It is what lets the site put a head back correctly after service in year seven.
Two checks worth running on any study handed to you:
Does the uniformity figure appear at all? Average lux alone hides the failure mode that high mast schemes actually suffer from, which is a bright ring under each mast and a dark seam between them.
Does the peak intensity arithmetic close? Peak candela divided by mounting height squared gives centre lux directly beneath the head. If the claimed level cannot be reached that way, something in the proposal is optimistic. The relationship is explained in lumens vs lux vs candela.
Step 4: Check the Structure Before the Fixtures
LED heads are often lighter than the HID assemblies they replace, which is helpful. They are not always, and wind area matters as much as mass.
Confirm three numbers with whoever owns the mast structure:
- Total head ring weight, new versus existing.
- Projected wind area of the new heads, since a broader flat body can increase load even at lower weight.
- Mounting interface, because bracket adapters change the moment arm and are frequently improvised on site.
A mast designed in 1995 to a wind loading code that has since been revised needs checking against the current code, whatever the new heads weigh. That is a structural engineer’s sign-off, and it costs a fraction of the alternative.
Step 5: The Lowering System Decides the Maintenance Budget
Every retrofit is a chance to fix access, and most waste it.
If the mast has a lowering system, the retrofit is the moment to service it: cable inspection or replacement, winch service, latch and ring check. Doing that while the heads are down anyway costs almost nothing and restores ladder-free maintenance for the next decade.
If the mast has no lowering system, price two futures honestly. One where every service visit is a crane hire, and one where a lowering system is retrofitted now. On a site with more than a handful of masts, the second usually wins, and it also removes the operational disruption that never appears in the fixture quotation.
Where crane access is genuinely unavoidable, that argues for group replacement: change every head during one planned outage rather than chasing individual failures. Group replacement makes documented L70 behaviour a purchasing criterion rather than a datasheet ornament, because you are betting on the whole population failing late and together.
Step 6: Electrical and Control Detail
Three specifications to settle before the order, because retrofitting any of them means going back up.
Surge protection comes first. Masts on long rural or port feeders sit at the exposed end of the range. Specify the rating in writing and confirm whether the protection device is field-replaceable.
Fit dimmable drivers even if no control system is planned yet. 0-10 V or DALI decided now costs little and keeps profile-based operation available later, which on a yard that runs at low activity for part of the night is where the remaining energy saving lives.
Review the circuits last. LED heads draw far less current, which sounds harmless and occasionally is not. Verify that existing protective devices still discriminate correctly at the reduced load, and check the power factor of the proposed drivers before assuming the feeder is oversized rather than mismatched.
What Changes Beyond Energy
The bill is the reason retrofits get approved. It is rarely the biggest operational change.
A HID head that trips takes 10 to 15 minutes to return. In a port or an interchange, that is a genuine operational and safety gap. LED returns immediately.
Output also stays where it was commissioned. HID dims measurably across its life, so a yard that measured well at handover was dim long before anyone replaced a lamp. LED with documented lumen maintenance holds its level, which is what makes a maintained lux target achievable rather than aspirational.
Higher colour rendering than HPS improves both human recognition and CCTV usefulness. Cameras also benefit from the flicker behaviour of a quality LED driver, which matters wherever footage is used for incident review.
Directional optics also let you stop lighting the sky, the neighbours and, at a port, the water. Where the site sits near residential boundaries or a berth, this is often the change that generates the most goodwill. See light trespass and, for waterside constraints, the port and terminal lighting guide.
The Bottom Line
A high mast retrofit is a maintenance-access decision wearing an energy project’s clothes. The wattage table gets the budget approved. What determines whether the site is still happy in year eight is whether the aiming was engineered and recorded, whether the structure was checked, whether the lowering system works, and whether the heads were chosen for surviving a decade rather than for winning a spreadsheet by two lumens per watt.
Send us the mast schedule, heights and the yard layout, and our engineers return the retrofit study with head counts, the aiming table, uniformity figures and the IES files behind them. Where the honest answer is that a redesign beats a one-for-one swap, or that the structure needs checking first, we will say so, because that is cheaper to hear now than from a crane. Our LED flood lights cover 50 W to 1200 W for mast mounting, and the ports and terminals page shows how the same fixtures are deployed across terminal zones.
FAQ
What LED wattage replaces a 1000W high mast head?
Typically 300 to 400 W of quality LED, delivering roughly 48,000 to 64,000 lm. The gap looks implausible until you account for two things: a reflector-based HID head loses a large share of its output inside the fixture, and the original design carried extra output to survive heavy lumen depreciation. Validate against measured fixture lumens and the IES file at your actual mast height rather than against the old lamp rating.
How much does a high mast retrofit save?
The energy saving follows the wattage ratio, which is usually a reduction to about a third of the original connected load once ballast watts are counted. The larger and less predictable saving is maintenance: crane hires, permits and operational downtime disappear when heads stop failing every few years. Size both from your own tariff and access costs, since the second number varies enormously between a rural interchange and an operating quay.
Should I replace heads one-for-one or redesign the scheme?
One-for-one when the existing scheme performs and the goal is energy and maintenance. Redesign when the operation has changed, complaints predate the failures, or head count per mast is high enough that removing two heads per mast pays for the study. Directional LED optics often hold the same level with fewer heads, so a redesign can cut connected load twice over.
Do LED heads need a structural check on an existing mast?
Yes, and weight alone does not settle it. Confirm the total head ring weight, the projected wind area of the new heads, and the mounting interface, since bracket adapters change the moment arm. A mast designed to an older wind loading code is not automatically compliant because the new heads are lighter. Get a structural sign-off before ordering.
What is the right maintenance factor for a high mast calculation?
Use 0.7 for outdoor masts on dusty, coastal or industrial sites with long cleaning intervals. The commonly quoted 0.8 belongs to clean indoor environments. Running the study at 0.8 on a container terminal overpromises by more than ten percent, and the shortfall shows up in year two rather than at handover.
Is it worth retrofitting a lowering system at the same time?
On sites with more than a few masts, usually yes. The alternative is a crane hire for every future service visit, plus the operational disruption that never appears in a fixture quotation. If the mast already has a lowering system, service the winch and cable while the heads are down, since the access is free at that moment and will not be again.
How should high mast heads be aimed after a retrofit?
From the photometric study, with tilt and rotation recorded per head as a deliverable. A ring of identically aimed heads produces a bright halo with a dark centre, which is the classic symptom of a mast commissioned by eye. The aiming table also lets the site restore correct performance after any future service visit, which is what keeps a scheme working through its second decade.