Choosing the Correct Cap Type
G12 single-ended lamps
G12 is widely used for tubular CDM-T, CMH-T, HCI-T, HQI-T and related lamps. It is common in retail spotlights, display fittings and architectural luminaires.
G8.5 compact capsules
G8.5 lamps are smaller ceramic metal halide capsules, frequently used in compact track lights, downlights and display fittings.
RX7s double-ended lamps
RX7s metal halide lamps have electrical contacts at both ends. They are common in HQI-TS, CDM-TD and other double-ended commercial or floodlighting products.
GX10 and GX8.5 reflector lamps
These caps appear on compact MR16-style and R111 reflector lamps. The reflector and beam angle form part of the lamp specification, so check these alongside the cap.
E27 and E40 screw caps
E27 Edison Screw and E40 Giant Edison Screw bases are generally found on elliptical and larger tubular lamps. E40 is particularly common across higher-wattage commercial, industrial and exterior products.
Do Metal Halide Lamps Need a Ballast?
Yes. Metal halide lamps are high-intensity discharge lamps and require compatible control gear to start and regulate the lamp. They must not be connected directly to a normal mains lampholder unless the complete fitting has been specifically designed to operate that lamp.
The required ballast is determined by more than wattage. Quartz and ceramic lamps can have different electrical characteristics, and some fittings also use a separate ignitor. If you are uncertain, check the luminaire label and control-gear reference or consult a qualified electrician.
Can Metal Halide Lamps Be Replaced With LED?
An LED conversion may be worthwhile when energy consumption, maintenance or long-term lamp availability is a concern. However, an LED bulb with the same cap is not automatically a safe direct replacement.
Some LED retrofit lamps require the existing ballast to be bypassed or removed. Others may not fit physically, distribute light correctly or manage heat safely inside the original luminaire. For large fittings, a complete LED luminaire replacement can sometimes deliver better performance than fitting an LED lamp into ageing control gear.
If maintaining the original fitting is important, a like-for-like metal halide replacement remains the most straightforward option—provided the complete specification matches.
Hard-to-Find and Discontinued Metal Halide Bulbs
Metal halide lamps are becoming more difficult to obtain as manufacturers reduce their conventional discharge ranges. However, that does not mean every existing metal halide fitting must immediately be replaced.
Lightsave Home holds remaining stock across numerous Philips, Osram, GE, Venture, Sylvania, Radium and Crompton ranges. This includes specialist ceramic lamps, unusual reflector formats, high-wattage industrial lamps and legacy product codes that may no longer appear in current manufacturer catalogues.
Where a product is described as discontinued or available from remaining stock, future availability cannot be guaranteed. Ordering against the exact lamp reference is especially important because a later replacement may not be obtainable.
