How to Connect an Electricity Meter Enclosure

How should an electricity meter enclosure be connected? This guide covers the connection process, enclosure locations and the main requirements.

Who may access the service connection enclosure?

Only an authorised employee of the distribution company, or someone granted access by the company, may work on the service connection enclosure. Customer-owned enclosures are generally not permitted, except for temporary connections. The distribution company usually owns and supplies the service connection enclosure.

Where to locate electricity meter enclosures

Standard electricity meter enclosures contain the metering equipment: the electricity meter, tariff switch and other devices, such as equipment for remote meter reading. The meter can also be installed in a shared distribution board with equipment downstream of the meter, provided the distributor’s requirements are met.

The distribution company specifies the location in its connection statement for the particular customer premises, issued after an application to connect.

What an electricity meter enclosure must look like

• Its design is primarily governed by standards ČSN EN 61439-1 and ČSN EN 61439-3.
• Distribution companies also set requirements in their own rules, known as connection requirements.
• Only an enclosure that complies with applicable standards and connection requirements may be connected.
• The enclosure must include documentation required by Act No. 102/2001 Coll., have a declaration of conformity under Acts No. 22/1997 Coll. and No. 90/2016 Coll., and bear the CE mark.

The enclosure must include a wiring diagram. Its door must bear a permanent electrical hazard warning symbol (a black lightning bolt on a yellow background inside a black-bordered triangle).

Connecting an electricity meter enclosure

Here are the main rules for connecting a meter enclosure. Remember that it is electrical equipment: only a qualified electrician may install, modify or repair it.

• Size incoming and outgoing conductors to at least 4 × 10 mm² for a TN-C system (the outgoing cable may alternatively be 5 × 6 mm² in a TN-S system).
• Split the PEN conductor (transition from TN-C to TN-S) only in a downstream distribution board or in the metered section of the meter enclosure.
• Connect individual conductors in the correct phase sequence (L1, L2, L3).
• For TT systems, the enclosure connection must be adapted. TT systems are now rarely used for customer connections in the Czech Republic.
• In TN systems, fault protection must be provided by automatic disconnection of the supply using an overcurrent protective device such as a circuit breaker.
• If the enclosure does not include a main circuit breaker upstream of the meter, it can be fitted in the designated position using the prepared conductors.

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