Splicing connector overvoltage category

Question

I have recently been reviewing the technical details for a popular brand of lever type splicing connector and, according to the information on the manufacturer&rsquo;s website, the connectors are only rated for use in overvoltage category II applications. My understanding is that for a fixed wiring installation to comply with BS 7671, all equipment must be rated for overvoltage category III (regulation 443.6.2 and table 443.2) i.e. be capable of withstanding an impulse voltage of 4 kV. The certification data, also published on the manufacturer&rsquo;s website, states that the connectors have only been tested to 2.5 kV. 
 I have queried this with the manufacturer, who advised that the 4 kV electrical strength test only applies to IT equipment. 
 I may well have misinterpreted the requirements, but I would be interested to hear anyone else&rsquo;s views on this.

gkenyon · Accepted Answer

For completeness, though, Overvoltage Category is important for some other kinds of products. 
 Most importantly for electricians, please make sure you use electrical test equipment of an appropriate overvoltage category depending on where you're using it, per Table 443.2 of BS 7671 . The overvoltage category is (for those who are learning about the industry) marked on conformant equipment as "CAT III", "CAT IV" etc. along with a voltage rating (or may be multiple pairs of category and voltage rating).

Geoff Lyons · Answer

Thank you very much for taking the time to prepare such a detailed response Graham. I believe we are both looking at data from the same manufacturer and I am not surprised to learn that my confusion is a result my misinterpretation of the requirements. 
 I think that the learning point for me is not to take the guidance in section 443.6.2 too literally and that the specific product standards will take precedence.

Geoff Lyons · Answer

That's useful to know, thanks Graham.

Splicing connector overvoltage category

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