Why does setting Wing/Engine Anti-ice on the ground cause Engine Bleed Fault lights to illuminate?

[Transair]

Due to rain and cold temps, I set the anti-ice to 'ON', on the ground during taxi and the engine bleed fault lights illuminated on the OHP, and ECAM.  Can't this be used on the ground?  What happens in icing conditions?  

Once turned off, the fault lights extinguished.