Sealing of Energy Meters

Electrical Energy meters are sealed to detect possible manipulations. They are not preventing tamper, but at least you know that someone has broken the seal and eventually manipulated the meter.
The utility field workers check the meter installations regular. If a broken seal is found, the reason will be investigated. Special field test equipment helps to verify the complete meter installation.

meter with seals
meter with seals

When the power company is using numbered seals, the existing installation is verified vs. the initial seal numbers. This is an additional measure to detect tamper.

If there is no specific utility request for numbered seals, the produced meters leave the factory with un-numbered seals. This seals are assuring that there was no manipulation during the transport. It's highly recommended that the utility replaces this seals with their own sealing scheme.

Sealing of electrical energy meter installations

This is a general selection, not all meters have all sealing positions.

  • Terminal cover
    The terminal cover has one or two seals to make the customer more sensitive that unauthorised opening of energy meters is forbidden. Electronic meters are also detecting when the terminal cover has been opened. Depending on the utility settings the internal relay will trip. It can only be reset by the power supply company.
    If an AMI system is installed, the utility operator receives an alarm. Date and time of opening are internally recorded. The detection also can work when the meter is not energized.
  • Main cover
    The main meter cover has typically two seals. Meters with a ultrasonic welding don't need seals as the main cover will be destroyed during the opening event. In any case an un-authorized opening will be detected and processed in the same way like the terminal cover opening.
  • Maximum demand reset button
  • Battery slot
  • Slot for exchangeable communication module
  • Optical communication port
  • Enclosure for the meter
  • Terminals for the instrument transformers (CT-meters)
  • CT-meter switch board
unnumbered seal
unnumbered seal
meter seal
meter seal, 90° turned
numbered seal
numbered seal
sealing pliers
heavy used tool for on-site sealing
twist lock seal
twist lock seal

The twist lock seal doesn't require an additional tool for fixing. The seal number can be wittten by laser on the front plate.

RFID seal
RFID seal CL7201H

High end digital sealing method

How do you handle the energy meter sealing? Please drop me a comment:)

Thank you for reading.

Editor's note: This article was originally published in December 2019 and has been updated for comprehensiveness.

10 Replies to “Sealing of Energy Meters”
  1. Could you please guide me how can I detect my meter is giving right or wrong reading ?
    Secondly, someone has opened my meter's terminal cover as my meter displays S4 what could I do to resolve this issue?

    1. From the meter itself, you can only take the reading. The meter is counting the consumption. If you feel like a sudden change based on your previous usage, you can ask your power company for an on-site check. Since you have a ‘terminal open' indication on the meter, you should inform the power company in any case. They have tools to verify the installation, to clear the display indication and to seal the meter.

    1. The billing registers of electronic energy meters can't be cleared. Your power company can find out the reason by reading the log files. Most likely, the meter needs to be exchanged.

  2. I buy a smart meter for my educational energy project.
    I want to read energy paramaters like value of active and reactive
    I try to connect to the meter from RS485 (A B) port with Hyperterminal by a rs495-rs232 convertor (serial port , baud rate , ..) but the meter has no response .
    Can you help me ?

    1. Thank you for the comment. The initial communication always starts on 300 baud. Then the meter acknowledge and returns a baud rate, typically 9600 bd. So the use of hyperterminal will be difficult. I suggest, you download the open source tools from Gurux. They also have a good forum to answer your questions.

    1. After manufacturing the meters are locked. From that time on the meter can't be reset any more. It's an essential part of protection against fraud.

  3. Hi, what can I do from the day my meter was was install terminal cover was open. Try call the power company no one have come. What I do to solved this problem.

    1. Only the power company can help you by closing and sealing the terminal cover. Then they will generate a clear tamper token.

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