Junction Boxes

One rated at or above the circuit it joins. The Knightsbridge SN8400 is a 5A box, the SN8410, SN8420 and SN8460 are 20A, the SN8430 is 30A and the SN8470B is 60A, which also takes cable up to 25mm². Outdoors, the IP68 gel boxes JB0014 and JB0015 are rated 24A, and the JB002 and JB004 connectors 16A.

Enough for the conductors being joined, so count the cores before choosing. The Knightsbridge SN8430, SN8430B and SN8470B are 3-terminal boxes, the SN8400, SN8410 and SN8420 families have 4 terminals, and the white SN8460 has 6 terminals in an 89mm body rated 20A.

An IP68 box, sealed against water, such as the Knightsbridge JB0014 3-way or JB0015 4-way weatherproof gel junction box. The pair are rated 24A and made from PA66, and the JB004 is an IP68 polycarbonate connector box rated 16A. IP20 boxes such as the SN8400 belong indoors, in dry places.

A junction box filled with gel that seals the joint against water once it is closed. The Knightsbridge JB0014 is supplied prefilled with gel and includes cable sleeves and a lever connector, the JB0015 4-way and JB0016 inline gel boxes are IP68 rated for H07RNF cable, and the JB0016 accepts cable diameters of 5mm to 14mm.

Use an IP68 inline connector or an inline gel box. The Knightsbridge JB0013 has lever terminals for tool-free connection and takes 5mm to 14mm cable through M22 glands, the JB002 has screw terminals and takes 0.75mm² to 4.0mm² H07RNF cable, and the JB0016 gel box is supplied with sleeves and a 3-way lever connector. The JB0013 lists repairing and extending cables as typical uses.

The indoor round boxes, SN8400 to SN8470B, state BS EN 60670, and the JB002 and JB004 outdoor connectors state EN 50262. The SN8470B, for example, is a 60A box certified to BS EN 60670 with built-in cable strain reliefs. When matching a box to an installation, check its rating and standard against the design of the circuit.

Yes, black and brown versions are made. The SN8400B, SN8420B and SN8430B are black versions of the white 5A, 20A and 30A boxes, and the 60A SN8470B is brown. Outdoors, the IP68 JB0013, JB0014, JB0015 and JB0016 are black, and so is the JB55BK garden box.

A garden box keeps plug-in connections dry outdoors, so a supply can run to seasonal lighting or equipment in the garden. The Knightsbridge JB55BK is IP55 and IK06 rated, with a five-channel gasket for one power input and four outputs, room for 4G trailing sockets, a supplied mounting bracket and a screwless design for easy access.

Where a diameter is stated, it is 59mm, 79mm or 89mm. The 5A SN8400 and 20A SN8410 are 59mm, the 20A SN8420 is 79mm, and the 30A SN8430 and 6-terminal SN8460 are 89mm. A smaller box fits a tighter void, and a larger body gives more room to dress conductors onto the terminals.