On Sun, 15 May 2016 13:42:47 -0700 (PDT),
wrote:

On Sunday, 15 May 2016 19:09:56 UTC+1, DerbyBorn wrote:
Intrigued - how come so little?

The solenoid doesn't hold the door open directly - it just holds a latch inside the closer which stops the closer operating.

The solenoids which attach to the wall and are no part of the door closer mechanism probably use more.

The figures given were for a solenoid attached to the wall.