OK, I've looked up some product standards and done some cross referencing.
The proposed BS7671 reg is a non reg. the requirement is already built into the product standard.
So, the changes will have already have been made by the manufacturers as the standard has been in place for a few years now.
As follows over the next few posts.
[SIZE=10pt]Actually, if the enclosures are CE marked, designed, built and tested to the relevant product standard, then, now, IF they are made of a polymer material then they WILL comply with that proposed regulation.[/SIZE]
[SIZE=10pt]Excerpts from BS EN 61439-1:2011 - Low-voltage switchgear and controlgear assemblies Part 1: General rules[/SIZE]
[SIZE=10pt]8.1.3.2 Resistance of insulating materials to heat and fire[/SIZE]
[SIZE=10pt]8.1.3.2.1 General[/SIZE]
[SIZE=10pt]Parts of insulating materials which might be exposed to thermal stresses due to internal[/SIZE]
[SIZE=10pt]electrical effects, and the deterioration of which might impair the safety of the ASSEMBLY, shall[/SIZE]
[SIZE=10pt]not be adversely affected by normal (operational) heat, abnormal heat or fire.[/SIZE]
[SIZE=10pt]8.1.3.2.2 Resistance of insulating materials to heat[/SIZE]
[SIZE=10pt]The original manufacturer shall select insulating materials either by reference to the insulation[/SIZE]
[SIZE=10pt]temperature index (determined for example by the methods of IEC 60216) or by compliance[/SIZE]
[SIZE=10pt]with IEC 60085.[/SIZE]
[SIZE=10pt]8.1.3.2.3 Resistance of insulating materials to abnormal heat and fire due to internal[/SIZE]
[SIZE=10pt]electric effects[/SIZE]
[SIZE=10pt]Insulating materials used for parts necessary to retain current carrying parts in position and[/SIZE]
[SIZE=10pt]parts which might be exposed to thermal stresses due to internal electrical effects, and the[/SIZE]
[SIZE=10pt]deterioration of which might impair the safety of the ASSEMBLY, shall not be adversely affected[/SIZE]
[SIZE=10pt]by abnormal heat and fire and shall be verified by the glow-wire test in 10.2.3.2. For the[/SIZE]
[SIZE=10pt]purpose of this test, a protective conductor (PE) is not considered as a current-carrying part.[/SIZE]
[SIZE=10pt]For small parts (having surface dimensions not exceeding 14 mm x 14 mm), an alternative[/SIZE]
[SIZE=10pt]test may be used (e.g. needle flame test, according to IEC 60695-11-5). The same procedure[/SIZE]
[SIZE=10pt]may be applicable for other practical reasons where the metal material of a part is large[/SIZE]
[SIZE=10pt]compared to the insulating material.[/SIZE]
[SIZE=10pt]10.2.3.2 Verification of resistance of insulating materials to abnormal heat and fire[/SIZE]
[SIZE=10pt]due to internal electric effects[/SIZE]
[SIZE=10pt]The glow-wire test principles of IEC 60695-2-10 and the details given in IEC 60695-2-11 shall[/SIZE]
[SIZE=10pt]be used to verify the suitability of materials used:[/SIZE]
[SIZE=10pt]a) on parts of ASSEMBLIES, or[/SIZE]
[SIZE=10pt]b) on parts taken from these parts.[/SIZE]
[SIZE=10pt]The test shall be carried out on material with the minimum thickness used for the parts in a)[/SIZE]
[SIZE=10pt]or b).[/SIZE]
[SIZE=10pt]If an identical material having representative cross-sections as the parts has already satisfied[/SIZE]
[SIZE=10pt]the requirements of 8.1.3.2.3 then the test need not be repeated. It is the same for all parts[/SIZE]
[SIZE=10pt]which have been previously tested according to their own specifications.[/SIZE]
[SIZE=10pt]For a description of the test, see Clause 4 of IEC 60695-2-11:2000. The apparatus to be used[/SIZE]
[SIZE=10pt]shall be as described in Clause 5 of IEC 60695-2-11:2000.[/SIZE]
[SIZE=10pt]The temperature of the tip of the glow-wire shall be as follows:[/SIZE]
[SIZE=10pt]– 960 °C for parts necessary to retain current-carrying parts in position;[/SIZE]
[SIZE=10pt]– 850 °C for enclosures intended for mounting in hollow walls;[/SIZE]
[SIZE=10pt]– 650 °C for all other parts, including parts necessary to retain the protective conductor.[/SIZE]
[SIZE=10pt]As an alternative the original manufacturer shall provide data on the suitability of materials[/SIZE]
[SIZE=10pt]from the insulating material supplier to demonstrate compliance with the requirements of[/SIZE]
[SIZE=10pt]8.1.3.2.3.[/SIZE]
[SIZE=10pt]This test applies only to enclosures and external parts of ASSEMBLIES intended to be installed[/SIZE]
[SIZE=10pt]outdoors and which are constructed of insulating materials or metals that are entirely coated[/SIZE]
[SIZE=10pt]by synthetic material. Representative samples of such parts shall be subjected to the[/SIZE]
[SIZE=10pt]following test:[/SIZE]
[SIZE=10pt]UV test according to ISO 4892-2 Method A, Cycle 1 providing a total test period of 500 h. For[/SIZE]
[SIZE=10pt]enclosures constructed of insulating materials compliance is checked by verification that the[/SIZE]
[SIZE=10pt]flexural strength (according to ISO 178) and Charpy impact (according to ISO 179) of[/SIZE]
[SIZE=10pt]insulating materials have 70 % minimum retention.[/SIZE]
[SIZE=10pt]The test shall be made on six test specimens of standard size according to ISO 178 and on[/SIZE]
[SIZE=10pt]six test specimens of standard size according to ISO 179. The test specimens shall be made[/SIZE]
[SIZE=10pt]under the same conditions as those used for the manufacture of the enclosure concerned.[/SIZE]
[SIZE=10pt]For the test carried out in accordance with ISO 178, the surface of the sample exposed to UV[/SIZE]
[SIZE=10pt]shall be turned face down and the pressure applied to the non exposed surface.[/SIZE]
[SIZE=10pt]For the test carried out in accordance with ISO 179 for materials whose impact bending[/SIZE]
[SIZE=10pt]strength cannot be determined prior to exposure because no rupture has occurred, not more[/SIZE]
[SIZE=10pt]than three of the exposed test specimens shall be allowed to break.[/SIZE]
[SIZE=10pt]For compliance, enclosures constructed of metals entirely coated by synthetic material, the[/SIZE]
[SIZE=10pt]adherence of the synthetic material shall have a minimum retention of category 3 according to[/SIZE]
[SIZE=10pt]ISO 2409.[/SIZE]
[SIZE=10pt]Samples shall not show cracks or deterioration visible to normal or corrected vision without[/SIZE]
[SIZE=10pt]additional magnification.[/SIZE]
[SIZE=10pt]This test need not be carried out if the original manufacturer can provide data from the[/SIZE]
[SIZE=10pt]material supplier to demonstrate that material of the same type and thickness or thinner[/SIZE]
[SIZE=10pt]complies with this requirement.[/SIZE]
[SIZE=10pt]I will enter the titles of the cross referenced standards at the end of the last post.[/SIZE]
msl1: 
