Lighting Design Process 3.



When selecting a manufacturer is important to consider their level of accreditation and whether they are able to meet the retailers code of ethics. We recommend using companies that are ISO14001and ISO9001 accredited or are members of a recognised industry body with a code of conduct.


To be dc certified manufacturers should be able to provide:

  • Comprehensive QC monitoring and recording
  • Supplier auditing and component tractability
  • Declarations of Conformity or Certificate of Conformity to required legislation (eg: CE)
  • Accurate and comprehensive technical information on products produced
  • Photometric data for light engines and luminaires
  • Compliance with all dc testing requirements
  • Factory testing

The manufacturer of display equipment will be required to carry out tests before and during the production process and be able to provide documentary evidence that testing has been carried out.


Pre-production testing should only be carried out on the display equipment that requires certification and include:

            dc 100             Topple test of display

            dc 101             Tilt test of display

            dc 102             Weight testing on shelfs

            dc 103             Vertical load test on doors

            dc 104             Horizontal load test on doors

            dc 104             Topple test on drawers

            dc 105             Climb test on drawers

            dc 106             Surface static load

            dc 107             Surface point load

            dc 108             Product lighting performance

            dc 109             Lightbox performance

            dc 110             Edge-lit acrylic performance

Details on each test and how they need to be carried out can be found in the Testing Guidelines.

Factory testing

Before carrying out any electrical inspection and testing a risk assessment should be carried out to identify any dangers present and enable any necessary precautions to be taken.

Test equipment should be constructed, maintained and used correctly to prevent danger. GS38 HSE publication gives suitable guidance on this.

Before you begin the inspection and test you will need all the necessary information including schematics, technical drawings, load calculations and intended environment of the equipment under test (EUT)

All work should be carried out in a safe manner. You should use a suitable test area where the risks can be controlled, making sure you have enough space, adequate lighting and proper access to the EUT.

All personnel carrying out the inspection and testing should have relevant training, skill and experience to prevent any danger during the inspection and testing process.

Electrical testing should only be performed by a person who is competent in the safe use of the test equipment and is able to interpret the results correctly.


Visual Inspection

A visual inspection must proceed testing, before the unit is energised.

Regulation 642.3 of BS7671 provides a list of items that should be included as a minimum

Further advise is available in the IET Guidance Note 3, Inspection & Testing publication and the IET code of practice for in-service Inspection and Testing of Electrical Equipment



The tests required for Design Conformity are,

  1. Earth Continuity Test (Class 1 Fixtures)
  2. Insulation Resistance Test
  3. Protective Conductor current/or touch leakage test
  4. Function test including Load test

Earth Continuity

The earth continuity test will apply to almost all fixtures designed using Design Conformity Guidance as the majority will have earthed metal gear trays as part of the design. This test should be carried out to all exposed conductive parts of the fixture, this may require multiple continuity tests with the highest reading being the one recorded. Due to the nature of many led power supplies it may be necessary to carry out a “soft” test which uses a test current in the 20mA to 200mA range

Acceptable results would be 0.1Ω + the resistance of the supply cable.

For example,

If we take a fixture supplied by a 3M length of 1.5mm 3 core flex, from Table VI.1 of IET code of practice for In-service Inspection we can see the protective conductor resistance at 20°C is given as 39.9mΩ, so in this example any reading in excess of .14Ω would need to be investigated


Insulation resistance test

The insulation resistance test will normally be carried out by applying a test voltage of 500V dc and measuring resistance.

This may not be possible on some fixtures that contain LED drivers or SMPS which may contain EMC filters or Surge protection devices. In this case the test voltage should be reduced to 250V dc. A note should be made on the test certificate by the inspector that the test was carried out at the reduced voltage for this purpose.



Productive conductor test

This test is a complementary test to the insulation resistance test and is especially important where a reduced voltage had to be used because of problems with EMC filters or SMPS or in the case of lower than expected readings during the Insulation resistance test.

The equipment should be switched on for this test and will be operating at supply voltage for the duration of the test. The person carrying out the test should take all the necessary safety precautions highlighted in their initial risk assessment of the inspection and testing procedure before initiating this test.


Substitute Leakage Test

Some Portable appliance testers(particularly handheld devices) carry out a substitute leakage test.

This is not a suitable replacement to the protective conductor/touch current test and is not recognised as an alternative to the insulation resistance test due to limitations in the way the instrument carries out this test.

Design Conformity will not except this test as an alternative to the protective conductor/touch current test.


Load Test 

When previous tests indicate it is safe to proceed, a full load test should be carried out on the EUT. The results, usually given in KVA must be included in the test results provided to Design Conformity

(This test is often combined with the protective conductor/touch leakage test when using a Portable Appliance Tester to carry out the tests).


The easiest way of carrying out these tests would be with a downloadable Portable Appliance Tester; this ensures test results are easily available if required for future testing/maintenance purposes.


If you have any doubts concerning inspection and testing, we recommend you consult a qualified electrical engineer who will have both the necessary experience and correct equipment required to carry out the task safely.



Labelling of Electrical Display Units

  1. All display units and systems powering luminaires must be clearly marked or labelled.
  2. Marking/labels have to be visible, legible, durable and clearly accessible to the person undertaking installation and maintenance tasks.
  3. Information must be provided in text not smaller than 2mm high.
  4. Tamperproof labels should be used rather than paper printed labels as these can be damaged by cleaning agents and or UV damage.
Information to be Included on Labels/Marking
1. Manufacturers identification and contact details (mandatory)
2. Manufacturers batch number of product for tradability (mandatory)
3. Test date and initials of person conducted test (mandatory)
4. Voltage rating of the unit (mandatory)
5. Rated maximum ambient temperature, if not 25°C.
6. Symbol for class II luminaires, where applicable.
7. Symbol for class III luminaires, where applicable.
8.IP rating, if greater than IP20.
9.The relevant symbol for suitability of direct mounting on combustible or non-combustible materials.
10. The unit rating (Watts).
11. Termination points. These should be marked to indicate polarity. For ELV cables, use red for live and black for neutral.
12. The earthing connection point.
13. The maximum number of luminaires that can be interconnected.
14. Nominal operating frequency.




Once the unit is ready to be inspected a dc appointed inspector will conduct a visual inspection and test the pre-production display equipment.


dc label and reference number

Manufacturers that pass inspection and obtain a dc certificate of conformity also gain the right to use the dc logo on their test label only when in conjunction with the dc certification number. EG:


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