AC voltage and calibration

[nickdd]

About the calibration:
I use SCT013-010  (10A 0-1V) clamp.
When I check the logs for some known loads (100W light bulb, 500W light and hair dryer) I got these values from the logs:

0.41A:  (100W bulb):
[22:28:14][D][sensor:094]: 'ai1': Sending state 1.01400 V with 3 decimals of accuracy
[22:29:14][D][sensor:094]: 'ai1': Sending state 1.01900 V with 3 decimals of accuracy
[22:30:14][D][sensor:094]: 'ai1': Sending state 1.01000 V with 3 decimals of accuracy

1.79A (500W halogen bulb):
[22:36:14][D][sensor:094]: 'ai1': Sending state 1.09700 V with 3 decimals of accuracy

6.56A (1500W hair dryer)
[22:23:14][D][sensor:094]: 'ai1': Sending state 1.24500 V with 3 decimals of accuracy

If I look at the datasheet the values should be between 0v (0A) and 1v (10A)
http://en.yhdc.com/comp/file/download.do?id=943

=> why do I always get values above 1V to start with?  
Or would that be an issue with the clamp?  They are supposed to be original SCT013's.
Picture:



Any help or advise is welcome!

Thanks,
Nick