The requirements of lamps used for the different types of photometric standard are stated and are related to the problems for the photometrist caused by the changes in the commercially available range of lamp types in the past 20 years. The need for suitable lamps to fill the gaps caused by discontinuation of the types used earlier in applied photometry led to NPL developing new heavy-current lamps for the purpose, in conjunction with GEC Ltd. The limited range of existing types of photometric standard lamps is described and the properties of the new lamps are contrasted with those of the existing ones. Principal advantages are robustness and the greatly improved range of possible combinations of operat-ing temperature and life. Although very reproducible in output over extended periods, the new lamps exhibit some convective gas fluctuation noise. While the effect of this can be reduced adequately by using a long time constant or integrating period in the photometry, steps are being taken to find ways of reducing the noise in the light output. Cases are discussed where commercial lamp types can still be used.