Mercury Vapor Light Ballast Replacement: A Comprehensive Guide
Mercury vapor lights, known for their durability and energy efficiency, are commonly used in large-scale facilities like warehouses, factories, and parking lots. However, like any electrical component, their ballasts can fail over time, leading to flickering lights or complete power loss. This guide will walk you through the process of mercury vapor light ballast replacement, ensuring your lights remain functional and safe.
Understanding Mercury Vapor Lights and Their Ballasts
Mercury vapor lights consist of a glass tube filled with mercury and a small amount of argon or another inert gas. An electrical current is passed through the tube, exciting the mercury atoms and causing them to emit ultraviolet (UV) light. This UV light then strikes a phosphor coating on the inside of the tube, which converts it into visible light. The ballast is the component that regulates this electrical current, ensuring it's stable and within the safe operating range of the light.
Signs of a Failing Mercury Vapor Light Ballast
Before you start the replacement process, it's crucial to identify the signs of a failing ballast. Some common indicators include:

- Flickering or blinking lights
- Lights that take a long time to warm up and reach full brightness
- Lights that are dimmer than usual
- Lights that cycle on and off repeatedly
- An audible buzzing or humming sound coming from the light fixture
Safety First: Preparing for Mercury Vapor Light Ballast Replacement
Before you begin the replacement process, ensure you follow these safety precautions:
- Turn off the power to the light fixture at the main electrical panel.
- Use a voltage tester to confirm that the power is off.
- Wear appropriate personal protective equipment (PPE), including safety glasses and gloves.
- Have a clean-up kit on hand in case of a mercury spill. This should include gloves, a spill kit, and a hazardous waste disposal bag.
Step-by-Step Mercury Vapor Light Ballast Replacement
Now that you've ensured your safety, follow these steps to replace the ballast:
1. Access the Ballast
Remove the light fixture's cover or lens to expose the ballast. You may need to use a screwdriver or a special tool provided by the manufacturer.

2. Disconnect the Wiring
Carefully disconnect the wiring from the old ballast. Take note of the wire connections to ensure you can reconnect them correctly to the new ballast.
3. Remove the Old Ballast
Once the wiring is disconnected, remove the old ballast from the fixture. It may be held in place by screws or clips, so ensure you remove these as well.
4. Install the New Ballast
Position the new ballast in the fixture, ensuring it's correctly oriented. Secure it in place using the screws or clips provided.
5. Reconnect the Wiring
Reconnect the wiring to the new ballast, ensuring it matches the original connections. If the new ballast has a different wiring configuration, consult the manufacturer's instructions for the correct connections.
6. Test the Light
Once the wiring is reconnected, turn the power back on at the main electrical panel. The light should now function correctly. If not, double-check your wiring connections and ensure the new ballast is correctly installed.
Choosing the Right Replacement Ballast
When selecting a replacement ballast, consider the following factors:
| Factor | Importance |
|---|---|
| Wattage | The new ballast should have the same wattage as the old one to maintain the light's brightness and efficiency. |
| Voltage | The new ballast should be compatible with your facility's voltage. Most ballasts are designed for 120V or 277V systems. |
| Type | Mercury vapor lights use either magnetic or electronic ballasts. Ensure the replacement ballast is the same type as the original. |
| UL Listed | UL Listed ballasts have been tested and approved by Underwriters Laboratories, ensuring they meet safety standards. |
Always consult the manufacturer's instructions for specific guidance on choosing and installing a replacement ballast.
Professional Assistance: When to Call an Electrician
While mercury vapor light ballast replacement can be a DIY project for many, it's not always suitable for everyone. If you're unsure about any aspect of the process, or if the task involves working with high voltages, it's best to call a licensed electrician. They have the training and experience to ensure the job is done safely and correctly.
In conclusion, mercury vapor light ballast replacement is a crucial maintenance task that can help extend the lifespan of your lights and ensure they continue to function efficiently. By following this guide and prioritizing safety, you can successfully replace a failing ballast and keep your facility well-lit.
More Details
21.04.2013 ... You can replace the ballast with any type you want just use a lamp that matches the ANSI rating of the lamp.

Explore a wide range of our Mercury Vapor Ballast selection. Find top brands, exclusive offers, and unbeatable prices on eBay. Shop now for fast shipping ...

19.06.2021 ... Comments ; Mercury Lamp Overload. Excitron · 930K views ; Wiring up the Magnetek 400 watt Metal halide ballast. Clayman's Lighting · 783 views ; High ...

02.12.2024 ... Mercury vapor lamps require specific ballasts incompatible with LED bulbs. To replace with LEDs, remove or bypass the ballast and install an ...

We specialize in providing cost effective replacement ballasts along with a large assortment of lampholders and lampholder accessories.

Mercury-vapor lights operate at an internal pressure of around one atmosphere and require special fixtures, as well as an electrical ballast. They also require ...
13.03.2024 ... I'm surprised to see so many people saying change the ballast or photo eye. A cycling light is a classic bulb failure.

17.10.2025 ... The closest match for a 100 watt mercury is a 70 watt metal halide, but you'll need to not use the ignitor. A 100 watt pulse start MH ballast ...

Replacement 1000w Mercury Vapor Ballast - 220V 50Hz. ... Light Towers · Light Towers with Generators · Megatower™. Hunting & Boating.

Warehouse-Lighting.coms Universal 250W 120-277V M58 H39 metal halide or mercury vapor ballasts are sold by the six-pack. They have a power factor of 0.9 and ...
All five products of its lamp family can replace conventional mercury vapor lamps 1:1 - without any changes of the fixture. The HRL types are frequently used in ...

24.04.2025 ... Are you considering replacing your Mercury Vapor Bulb with an LED light fixture? This video will guide you through the benefits and process ...

21.04.2025 ... Mercury-vapor lights operate at an internal pressure of around one atmosphere and require special fixtures and an electrical ballast. They also ...

03.07.2019 ... In the US you haven't legally been able to buy new mercury vapor lamps or replacement parts since 2008 due to energy and toxicity concerns.

Mercury vapor lamps do require a ballast. These lamps produce light by ... Sometimes, a simple replacement of the entire ballast may be necessary for optimal ...

Download scientific diagram | Electronic ballast driver for mercury vapor lamp. from publication: On mercury vapor lamps and their effect on the smart-grid ...

175 watt Mercury Vapor Ballast kits to replace existing core and coil ballasts for this popular lamp. These are for standard MV400 lamps and have everything ...

06.12.2010 ... The mercury vapor ballast is a device that works with mercury vapor lamps ... How to Replace a Light Ballast. By Jason Pelmont · A white ...

28.10.2024 ... Fixture Type: yardblaster security light ; Ballast Type: Designed for running on North American 175W M57 probe start metal halide and 175W M137/ ...
19.01.2020 ... A mercury vapor bulb has a ballast, best to replace the whole fixture. ... First gut the light fixture remove ballast and bulb base. You ...