Buyer guides

What the letters after the wattage mean, and why two lamps of the same wattage are not interchangeable.

Why the cheapest lamp is not always the cheapest hour, and the one number to put on your spreadsheet.

Replace on hours, not on failure. What an aged lamp looks like and why the last hundred hours are the dangerous ones.

How pressurised lamps travel safely by air, what the packaging must include, and what to check on delivery.

The tariff heading for arc lamps, what customs asks for, and where to find the duty rate for your country.

Each projector maker uses a different lamp family, and some need an adapter. A quick map before you order.

Reversed polarity, fingerprints, loose terminals and starved cooling account for most early failures. Here is the list.

Same quartz, same gas, same geometry — so where do compatible lamps differ, and how do you protect yourself?