400W Metal Halide LED Replacement: 125W Corn Bulb Guide

400W Metal Halide LED Replacement: A Guide to the 125W Corn Bulb

Looking for a dependable 400W metal halide LED replacement? Many warehouses, plants and gyms still run 400W metal halide, high-pressure sodium (HPS) or other HID lamps, and they cost a lot to power and maintain. The 125W LED corn light bulb is made to replace them in the same fixture. It screws into a standard E39 mogul socket, puts out up to 15,625 lumens and draws 125W, against about 455W for a 400W metal halide fixture with its ballast.

Here's how it compares, what it saves, where it fits and how to install it.

Key takeaways

• The 125W LED corn bulb is rated to replace a 400W metal halide, HPS or HID lamp in the same E39 socket.
• It cuts each fixture from about 455W to 125W: roughly $217 a year at 12 hours a day and 15¢ per kWh.
• Choose by lumens, not watts. It gives 13,125–15,625 lumens, so check that's enough light for your space.

What is the 125W LED corn bulb?

A corn bulb is an LED lamp with rows of small LED chips set around a cylinder, like kernels on a cob. It screws into the socket the HID lamp came out of, and its light spreads out around it in the same way. Our post on 360-degree corn bulbs shows how they're built.

It's a commercial retrofit lamp: it needs a large E39 mogul socket, and the old ballast comes out of the circuit.

How many lumens does a 400W metal halide lamp make?

A new 400W metal halide lamp is rated at about 32,500 to 40,000 lumens, depending on the type; the common clear mogul-base lamp is rated 36,000. That's its output when new. Metal halide lamps lose light as they age.

That's why lighting makers say to match lumens, not watts. Lighting guides put a 400W replacement anywhere from about 10,000 to 22,000 LED lumens, depending on the space and how much light you need.

At 13,125–15,625 lumens, the 125W corn bulb sits in that range, but below a new 400W lamp. It's a good fit where the old lamps have aged or the space has more light than it needs. If you need as much light as new 400W lamps gave, a new UFO LED high bay is the better upgrade.

400W metal halide vs LED: why switch

Metal halide lamps also lose brightness as they age, and most fail by simply not relighting. An LED avoids the warm-up wait and the frequent lamp changes, and it loses light far more slowly, so you spend less on lifts and labor.

What it saves

Each fixture you switch from a 400W metal halide lamp (about 455W with its ballast) to the 125W corn bulb cuts about 330W. At 12 hours a day, that's about 1,450 kWh a year per fixture, or about $217 at 15¢ per kWh. Swap 20 fixtures and you save more than $4,300 a year. Your electricity rate will differ.

Where the 125W corn bulb works best

• Warehouses and manufacturing plants. High bay fixtures that held a 400W lamp.

• Gyms. High ceilings that need even light across the floor, as long as the fixtures have standard E39 sockets (see below).

• Parking garages. Fixtures that run long hours under cover.

• Retail back rooms and farm buildings. Storage areas, barns and workshops with mogul-base fixtures.

If your high bay points light straight down, a 180-degree directional corn bulb puts more of it on the floor.

Where not to use it: in wet locations where rain or spray reaches the lamp, in enclosed fixtures smaller than 450 × 280 × 280 mm, in fixtures with an EX39 "exclusionary" socket, or on a dimmer circuit.

Check the socket first. This bulb has a standard E39 base. Some open fixtures (no lens) use an EX39 "exclusionary" socket that only takes protected metal halide lamps, and an E39 bulb won't work in it. The electrical code calls for these sockets, or enclosed fixtures, over the playing and seating areas of indoor sports facilities, so check gym fixtures first.

How to install a 125W LED corn bulb

This is a Type B, ballast-bypass lamp: it runs on line voltage, so the old ballast comes out of the circuit. Have a licensed electrician do the wiring.

1. Turn off power to the fixture at the breaker.

2. Remove the old 400W metal halide or HPS lamp.

3. Remove or bypass the ballast, and wire the socket straight to line voltage (100–277V AC). Make sure the socket and wiring are rated for that voltage.

4. Check the fixture: a standard E39 socket (not EX39), a damp location at most, and in an enclosed fixture a lamp compartment of at least 450 × 280 × 280 mm.

5. Screw the bulb into the E39 socket and restore power.

6. Mark the fixture as converted to LED, so no one fits an HID lamp in it later.

Don't connect the bulb to a dimmer.

Built to last: surge protection, cooling and UL listing

• 6kV surge protection. Power surges are common in commercial and industrial buildings. The built-in protection guards the bulb against voltage spikes.

• Fanless cooling. A large aluminum heat sink carries heat away from the LEDs, with no fan to wear out.

• UL listed. It meets UL safety standards, which matters to the contractors and inspectors who sign off on the work.

Other corn bulb sizes

Not every fixture held a 400W lamp. Match the corn bulb to the lamp you're taking out:

• 150W HID, in a fixture that points down: 27W 180-degree corn bulb

• 600W metal halide, HPS or HID: 200W LED corn bulb

Ordering and support

The 125W LED corn bulb comes in 4000K natural white with a three-year warranty. For larger projects, contact Green Light Depot by phone, email or the online inquiry form. Our lighting specialists can help with product selection, technical questions and bulk pricing.

The bottom line

The 125W LED corn bulb is a simple 400W metal halide LED replacement: same E39 socket, about 330W less per fixture and no warm-up wait. Check that 13,125–15,625 lumens suits your space, then shop the 125W LED corn light bulb or compare our full range of LED corn bulbs.

FAQs

What LED replaces a 400W metal halide lamp?

Match lumens, not watts. The 125W LED corn bulb is rated to replace a 400W metal halide, HPS or HID lamp and gives 13,125–15,625 lumens. For more light, consider a new LED high bay.

How many lumens is a 400W metal halide lamp?

About 32,500 to 40,000 lumens when new, depending on the lamp, and less as it ages.

Does it replace 400W HPS lamps too?

Yes. It's rated for fixtures that held a 400W metal halide, HPS or HID lamp.

Do I have to remove the ballast?

Yes. It's a ballast-bypass (Type B) lamp, so remove or bypass the ballast and have a licensed electrician do the wiring.

Can I use it outdoors?

Yes, in damp locations such as a covered area light or canopy, from −40°F to 113°F. Keep it out of direct rain and spray.

Can I dim it?
No. The manufacturer says not to use it with dimmers.

Will it fit an enclosed fixture? Only if the lamp compartment is at least 450 × 280 × 280 mm (about 17.7 × 11 × 11 in).

Will it fit my fixture's socket?

Only a standard E39 mogul socket. It won't work in an EX39 "exclusionary" socket, which some open fixtures use for protected metal halide lamps.

How long does it last? It's rated for 50,000 hours, about 11 years at 12 hours a day, and it has a three-year warranty.