Wow, thanks for the quick and informative replies.
I'll try to find out more about the meters when I have access to them again.
As for the duration of the pulses, I'm going to guess that they are 0.1s since the counters claim they work at 10Hz.. EDIT: It sounds like there are multiple counter outputs on these meters (10 kWh, 100 kWh, 1000 kWh), that give different levels of accuracy. I'll see if I can find more about these pulses and get back to you.
Thanks again for the help.