Meter Field Testing - Sealing Points
The meter seal should be tamper proof. The consumer should be briefed about seals. The sealing of all metering systems should be completed at several points (as applicable) to prevent tampering. There should be at least one seal at all points described below (wherever applicable):
a) CT Secondary Boxes (further to locking arrangement)
b) PT Secondary Box (further to the locking arrangement)
c) Meter Cabinet
d) Meter Test Block
e) Meter Terminal Cover
f) Meter Cover
g) Panel doors where CT and PT secondary circuits are terminated or whereas possibility for shorting or breaking exists and fuses/links are given.
h) PT selector relay box where automatic change-over of potential supply to meter from one PT to another is given
i) CT Primary Links and Top Covers
j) MD Reset Push Button
k) Boxes/Cabinets containing terminals for remote transmission of metered data through communication channels, junction boxes in the system and boxes wherein interface devices are mounted.
l) Meter reading port.
Seals are essential to guard against the tampering of connections and internal elements of a meter. Tampering of seals will provide consumers access to the relevant part of a meter installation where s/he could manipulate the unit to record less energy leading to commercial loss. A seal is placed to detect unauthorized entry to the meter internals. The effectiveness of the seal depends on the category of seal (whether it is tamper proof or not, whether a duplicate could be acquired or not, etc.), and the procedures used in tracking the seals.