Tronic Sodium E40 Bulb 400W

Our review

This is a 400-watt sodium lamp from Tronic with an E40 base, the large screw fitting used on high-wattage discharge lamps. Sodium lamps of this type have no starting electrodes inside the bulb, so they cannot strike on their own. A ballast is required, and that ballast must contain an electronic starting circuit that generates a high-voltage pulse and sends it to the lamp's operating electrodes. The ballast also regulates the arc current and supplies the correct voltage once the lamp is running. Because of this, the bulb is only as good as the control gear paired with it, and a mismatched or failing ballast is a common reason a sodium lamp appears dead. Before buying, confirm your fixture takes an E40 base and that your existing ballast is rated for a 400-watt sodium lamp with pulse starting. If you are replacing an old bulb that worked until recently, the lamp is the likely culprit; if a new bulb still will not light, suspect the ballast instead. Compare against other 400W sodium options mainly on base type and ballast compatibility, since those determine whether the lamp will work at all in your setup. It is available on Sokonia.