How High Can I Install Access Control Readers?

What heights can I get away with on reader heights. Client is looking at mounting at 1400

When you say 1400, what unit do you mean? Millimeters?

Since they most commonly operate doors, card readers are usually installed at the same height as door hardware. Here in the United States, this ranges between 34 inches (864 mm) minimum and 48 inches (1219 mm) maximum above the finished floor.

On my projects, I specify reader heights to be at 40 inches (1016 mm) above the floor.

If you're using 'mm', I'm not sure ADA applies in your region, but you may have similar accessibility requirements for people in wheelchairs.

In the US, the 'not to exceed' height without exemption is 48" (1219mm):

(From our Disability Laws, ADA and Access Control note.)