Rayleigh instruments ri 122 100 p three phase mid certified 100a meter rayleigh instruments ri 122 100 p p the rayleigh instruments ri 122 100 p is a mid approved and certified three phase network kilowatt hour active energy meter it is housed in a 122mm wide 7 module din rail mounting case it can be directly connected up to 100 amps and has pulse output 1000 impulses kwh as standard p p the use of mid certified electricity meters has been made mandatory on private electrical