AMW ask your electrician if he used GFIC class A or B or GFPE. If he used GFIC class A those are designed to trip at 5mA and a CFIC B is 20mA. The GFIC is for personal protection and as stated above come in 2 different rating, and a GFPE is for equipment protection. Reading HP specs it looks like you may need a GFPE because they say 30mA at 20A, but using a GFPE in a residential setting could be an issue because they are not designed to protect individuals form a potential/lethal shock hazard.
Now this may solve your problem with why the breaker is tripping, I would ask HP if a GFIC class B is acceptable, if not then your electrican would need to see if codes/zoning allows a GFPE to be installed in the location the printer is being installed in.
Hope this clarifies this for all. This printer doesn't look like HP intend them to be installed in a residential setting.