What is “Accessible” in BS 7671?

Sarah Burrows of WAGO breaks down the confusion surrounding the term “accessible” in the BS 7671 regulation.

BS 7671 states that “a junction box with screw terminals must be accessible” so that connections can be available for inspection, testing and maintenance. However, the standard doesn’t actually define exactly what is meant by “accessible”, leaving the interpretation of the word somewhat open to debate.

Stipulating that connections should be accessible is a logical and welcome rule, but in some situations, installers could perhaps
benefit from some clarification as to what is accessible and what isn’t in order to improve consistency across the industry. As it stands, one person’s definition of accessible might be quite different to that of his or her industry colleagues, while electricians, consultants, designers and assessors all might have their own interpretations. No one wants their work pulled up on an assessment and have to rewire, especially if it’s arguably just the result of a grey area in The Regs. However, as I’ll discuss later, BS 7671 does offer provisions for a solution even if an area is deemed inaccessible.

Furthermore, it could be argued that ambiguity in the regulations is, in fact, essential to take into account the fact that no two installations are the same, and that what seems accessible in the context of one building may quite reasonably be considered inaccessible in another.

Take for instance laminate flooring. Some say that placing a junction box under laminate flooring would render it inaccessible. However, you could also argue that if the laminate can be lifted and replaced without damaging the property or its contents, then whilst this may be highly inconvenient, the connections can still be accessed. Just because a connection is difficult to access, so the argument goes, does not mean it is inaccessible. And if lifting the floor truly is the best option available, then that option starts to look rather more accessible when compared to the alternatives. The point is that without BS 7671 defining it specifically one way or another, these arguments are going to continue to rumble on.

In an ideal world all connections would be accessible so that they can be inspected and maintained, but in reality, there are occasions when it’s simply not possible to provide accessible connections. This could, for instance, be a project in a listed building where floorboards physically can’t be lifted, or a property where removing panels would create a structural risk, or if there simply isn’t enough space.

Important role

Electricians have a role to play in raising awareness of the issue amongst other trades, and ensuring that their own installations can be accessed wherever possible in case the work, for whatever reason, has to be revisited in the future.

Of course, one way to side-step the whole accessible vs inaccessible debate altogether is by using a maintenance-free configuration, which provides a secure and reliable option for the occasions when inaccessible installations are necessary, whilst conforming to BS 7671. These require the use of certain screwless terminals and enclosures to secure connections indefinitely. Screw-type products cannot be used as part of any maintenance-free accessory as they invariably require re-tightening over time, and repeated temperature cycling can and will cause them to eventually fail, therefore making them unsuitable for inaccessible areas.

Maintenance-free enclosures have to meet BS 5733, which applies to electrical accessories not already covered by BS 7671. The tests required to meet it are highly stringent and include long duration tests, vibration tests and current overload tests which test the terminals far beyond normal operating parameters, ensuring that they considerably outperform non-maintenance free products. Enclosures also have to be marked with the “MF” symbol.

So in summary, for a maintenance-free installation you require:

• Screwless term
  inals that are suitable for the type and size of conductor you are using, which have been tested and meet all relevant product standards and European directives, as well as the requirements of BS 5733

• A suitable junction box that is compliant with BS 60670-22 (applicable standard for junction boxes) and BS 5733 (applicable standard for accessories), as well as showing both the MF and CE marks, and meeting all relevant European directives

It’s important to note that the connectors and the enclosure do not qualify on their own as maintenance-free accessories. This is because an accessory is defined as the whole equipment and may comprise of two separate products – the connectors and the enclosure – both have to be certified for use together and installed according to the manufacturer’s instructions.