Hi Gaux ,
You are right and your readings are correct for load more than 20% , I have the same with my equipments,If you use second CT with half ratio of installed one you will get correct results,this case is explained well by IEC conerning with p.f measuring equipment.
Ameer
Defintely they need to be earthed and you can use the armour as earthing conductor if you will use an earth leakage CB 0.300 Amp. to protect persons against step and touch voltage due to earth fault current .