This article is a continuation of the first part of the Hager Junction Box Guide to the 17th edition. Find out more about the
- Building Regulations;
- Requirements of the 17th Edition Wiring Regulations;
- Downlighter Junction Box;
- Maintenance Free Connections;
- Traditional Junction Boxes;
- Product Selection Guide;
- Selection Chart.
Maintenance Free Connections
Junction boxes are commonly used during alterations and additions to an installation. With certain exceptions regulation 526.3 requires that every connection shall be accessible for inspection, testing and maintenance. The Electrical Safety Council Technical Manual states that “a junction box with screw terminals is an example of where connections must be accessible”. The reason is to allow inspection of joints which could have relaxed or loosened over time, a recognized problem with screwed terminals.
Unless provision is made for access, where boarding, carpet or other similar covering is laid over a junction box with screw terminals, it may not be considered accessible and maintenance free terminals should be used. This is further reinforced in Appendix 15 of the Wiring Regulations which states “Junction boxes with screw terminals must be accessible for inspection, testing & maintenance or, alternatively, use maintenance-free terminals / connection (Regulation 526.3)”
Tests, including long term vibration, shock test, long term connection test, pull out, voltage drop, temperature rise and exposure to corrosive atmospheres validate the suitability of these terminals. Equally suitable are solutions such as a ‘joint made by a compression tool’.
Maintenance free terminals have the additional advantages of allowing the direct insertion of solid, stranded or flexible conductors, and allowing the connection of up to four conductors from 0.5mm2 to 4.0mm2(see Hager J501, Hager 803 and Hager J804).
Traditional Junction Boxes
As we have discussed, unless using a solution such as maintenance free terminals, the access to electrical connections should be adequate for their safe and proper inspection, testing and maintenance. In this respect, connections should be in a location where they can reasonably be reached and where there is adequate working space.
Where connections are made in roof spaces and inter-floor spaces the enclosures containing the connections should normally be fixed and provision must be made for their access.
Providing these two constraints are complied with, then the continued use of standard circular junction boxes remains acceptable.
Providing the enclosure is fixed and accessible traditional junction boxes are acceptable.
The requirement for accessibility applies equally to the situation where, because of damage to an existing cable, a repair is effected by the introduction of a joint. The joint must be accessible, alternatively the joint may be made by an appropriate method, a maintenance free terminal for example(see Hager J501, Hager 803 and Hager J804).
Some conclusions regarding the 17th edition compliant Junction Boxes
- Junction boxes are an integral part of virtually every electrical installation. Unfortunately these connections often do not comply with the Wiring Regulations due to incorrect product selection.
- It is clear that careful consideration from designers and installers will be required to meet the requirements of the 17th Edition of the Wiring Regulations.
Product Selection Guide
17th Edition Junction Boxes Selection chart
|Description||No of terminals||Terminal Rating||Reference||Benefits / Considerations|
|Downlighter Junction Box||3 x 3 x 1.5mm2
1 x 2 x 1.5mm2
|16A||J501||Provided with cable clamps and
separate terminals for flex
|Maintenance Free Junction Box||3 x 4 x (0.5-4.0mm2)
4 x 4 x (0.5 – 4.0mm2)
|Suitable for use in inaccessible
|Traditional Junction Boxes||4
|Acceptable for locations which are
Download this 17th Edition Junction Boxes guide by Hager online here, or read part 1 and part 2 on our website. To purchase online 17th edition junction boxes, visit the Electrical Items section, Accessories, Junction Boxes. Some of the Hager 17th Edition compliant junction boxes are: Hager J501, Hager 803 and Hager J804.