Sound like a Billy ConnolIy special Chris,if it's a 240v "Jobby"Tony,
Most of the black lights on the market aren't really up to what we need unless you can get the room properly dark. I used to have a battery black light from a CC supplier, but to all intents and purposes it was a snide money detector and total cr*p for finding urine in carpets.
I then bought a pukka 240v jobby and it works a treat, even in only slightly dark rooms. It takes a couple of minutes to warm up and does get very warm in use, actually came very close to scorching a carpet once with it . I don't know where you can get them now, where I got mine from don't do them anymore. Worth it's weight in gold on urine jobs it is.