Description
UV ballast PH5-425-40 Oman — 425mA electronic driver for 40W germicidal lamps

The PH5-425-40 UV ballast is the 425mA electronic driver used with 40W germicidal lamps in ultraviolet water sterilizers, and UV Water Systems stocks it in Muscat. It supplies the strike voltage and the regulated lamp current a low-pressure UV-C tube needs, and the current rating is what determines the lamp’s actual 254 nm output — not the lamp alone.
The 425mA rating is the point most often missed. A 40W tube run on a lower-current driver will light normally and look perfectly healthy while delivering well below its rated UV-C. Nothing in the chamber flags it unless the system has a UV intensity sensor, so the water leaves under-dosed with no alarm and no visible symptom.
UV ballast PH5-425-40 Oman — technical specifications
| Type | PH5-425-40 |
| Output current | 425 mA |
| Lamp rating | 40 W single lamp |
| Construction | Electronic, potted |
| Function | Strike and regulated current control for low-pressure UV-C lamps |
| Mounting | Panel or DIN, plant room or enclosure |
| Supplied by | UV Water Systems — Uniqueness View LLC, Muscat, Oman |
UV ballast PH5-425-40 Oman — lamp compatibility
- GPH843T5L 40W 843mm 4-pin
- GPH810T5L 40W 810mm 4-pin
- Viqua / Sterilight S36RL 40W
- Philips TUV 36T5 HE 40W G5
- Other 40W standard-output single germicidal lamps at 425 mA
Match the ballast to the lamp, not to the chamber. High output lamps such as the Philips TUV 36T5 HO (75W) or the Viqua -HO series need a high output driver, not this 425mA unit. Confirm the input voltage and the connector type on the existing ballast before ordering a replacement.
Where the UV ballast PH5-425-40 Oman is used
This is the most common single-lamp ballast on commercial UV installations in Oman — villa whole-house units, restaurant and café water lines, clinic and school drinking water systems, post-RO polishing on commercial machines, and individual positions in small multi-lamp banks. We supply it as a spare and as part of ballast replacement programmes for clients running several UV systems across multiple sites.
Diagnosing a failed UV ballast PH5-425-40 Oman
A UV lamp that will not strike is not always a dead lamp. Before condemning the tube, check the ballast. The usual sequence is: confirm supply voltage at the ballast input, check the lamp pins and holder for corrosion or heat damage, then fit a known-good lamp. If a known-good lamp still will not strike, the ballast has failed. If the lamp strikes but the controller reports low UV intensity, the fault is more likely the lamp or a fouled quartz sleeve.
Ballasts fail more often in Oman than the manufacturer’s life figures suggest, and the reason is heat. A driver mounted in an unventilated plant room at 45 degrees ambient, or bolted to the sun-facing side of an outdoor enclosure, runs its electrolytic capacitors well beyond their design temperature. Mount ballasts in shade with airflow, keep them off hot pipework, and expect to replace them on a defined cycle rather than on failure at any site where the plant room is not cooled.
Standards and references
The UV dose a chamber must deliver, and the reasoning behind the annual lamp change, come from published drinking water guidance rather than from equipment marketing. The WHO Guidelines for Drinking-water Quality set out the microbiological targets disinfection is designed to meet, and the International Ultraviolet Association publishes the dose and validation practice the industry works to. We size and service UV systems in Oman against those references.
Buying a UV ballast PH5-425-40 Oman in Oman
UV Water Systems has supplied and serviced ultraviolet disinfection equipment across the Sultanate for more than 14 years, for hospitals, oil and gas sites, schools, hotels, food and beverage plants and villas. We keep UV ballasts and germicidal lamps in stock in Muscat, so a system that loses disinfection does not wait weeks for an air freight shipment.
Uniqueness View LLC is ISO 9001:2015 certified. Call +968 9763 7786 or email sales@waterfilteroman.com for stock, bulk pricing on service-contract quantities, or help matching a ballast to a lamp you cannot identify. Send a photo of the lamp, the old ballast label and the chamber nameplate and we will specify the correct unit. Our technicians cover Muscat, Sohar, Nizwa, Salalah and Duqm.
See also our UV sterilizer systems, UV lamps and spares and replacement quartz sleeves.



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