Three power board workers have been admitted to Palmerston North hospital's emergency department after being exposed to an unknown chemical.

Fire assistant area commander for Manawatu Roger Calder says the three men suffered skin burns and trouble breathing, after being exposed to a distribution board that had been in a fire, in a transformer.

Mr Calder says they drove themselves to the hospital, with the distribution board in the back of their ute.

He says they're in ED being tended to, and the Fire Service has secured the scene.

It's made it safe by removing the board to a sealed container, and decontaminating those personnel involved.

Roger Calder says the hospital carpark was cordoned off, but will reopen soon.

He says the hospital itself wasn't closed, and was able to operate as normal.