In this article, Contactum looks at some of the compliance requirements of BS EN 61439-3 and the responsibilities manufacturers have to fulfil before certification is granted. The company shares excerpts taken directly from its Defender 2 test reports.
Within BS7671, the Wiring Regulations, Regulation 421.1.201 states that “within domestic (household) premises, consumer units and similar switchgear assemblies must comply with BS EN 61439-3…” Certification to BSEN 61439-3 requires a variety of tests to be performed (listed below). Certification will only be granted on successful completion of each test. These tests are onerous and designed to prove the unit is able to perform way past its normal expected operational design characteristics.
- Resistance to corrosion
- Verification of resistance of insulating materials to abnormal heat and fire due to internal electric effects
- Verification of protection against mechanical impact (IK code)
- Degree of protection (IP code)
- Clearance and creepage distances
- Effective earth continuity between the exposed conductive parts of the assembly and the protective circuit
- Short-circuit withstand strength of the protective circuit. Conditional short-circuit test
- Incorporation of switching devices and components
- Internal electrical circuits and connections
- Terminal for external conductors
- Power frequency withstand voltage test
- Impulse withstand voltage test
- Temperature-rise tests
- Short-time withstand current test
- Short-circuit withstand strength test. 16kA test with fuse (Annex ZB)
- Dielectric verification
- Electromagnetic compatibility
- Mechanical operation
Some of the tests are more critical than others, but all are mandatory for the unit to be certificated. Below, Contactum shares some of the more arduous tests carried out, directly from its reports.
Verification of resistance of insulating materials to abnormal heat and fire due to internal electric effects
The test was performed according to BS EN 61439-3, Clause 10.2.3.2. The test specimen is conditioned for at least 24 hours at a temperature between 15ºC and 35ºC and a relative humidity between 45% and 75%. Once removed from the conditioning atmosphere, the test specimen is tested within 30 minutes.
The wrapping tissue and the wooden board to be placed underneath the test specimen are specified in 5.3 of IEC 60695-2-10. They are conditioned for a minimum of 24 hours at a temperature between 15ºC and 35ºC and a relative humidity between 45% and 75%.
The test specimen is considered to have withstood this test if there is no ignition, or if all the following situations apply:
a) The longest sustained and continuous flames or glowing of the test specimen after removal of the glow-wire extinguish within 30s
b) The specimen is not totally consumed
c) There is no ignition of the wrapping tissue
The temperatures are as follows: 960 ± 15ºC for insulating materials supporting live elements (terminal connectors); and 650 ± 10ºC for insulating materials not supporting live.
This test was performed according to BS EN 61439-3, Clause 10.10.2.3.5. The load distribution in the different tested panels, and the cables cross section, are shown in the table.
When this test is performed, a load is connected to the outgoing breakers as per the table. The temperature is monitored for heat rise.
The result: we have the full rating of board without derating the outgoing circuits.
Annex ZB of BS EN 61439-3 is a verification of the Consumer Unit to withstand a 16kA fault. This is specific requirement for consumer units used within UK installations.
When choosing Defender 2, you are guaranteed a quality safe and beautifully designed consumer unit which meets the stringent requirements of BS EN 61439-3. Third party type test certification is not a mandatory requirement, however, Contactum believes that when choosing Defender 2 you are guaranteed a quality, safe and reliable designed consumer unit which meets the stringent requirements of BS EN 1439-3.