How NOT to Terminate 3 Core SWA Cable

I had problems with a low resistance fault on a ring final circuit during testing last week. After breaking the ring into sections I identified the defective section. I had to lift the floorboards in a bedroom to check for any cable defects or jointed connections. I was surprised to find the following junction box connection. It was connected to a supply to the detached garage outside.

How NOT to Terminate SWA Cable

The picture above shows SWA cable supplying a detached garage. The cable was connected into domestic Ring Final Circuit [RFC] under upstairs bedroom floor. SWA outer armour was not bonded at either end of cable run. PME/TNCS earthing system, so no adequate means of earthing in the garage. The SWA circuit cable was disconnected for safety reasons.

The picture below shows what should be done. A correct gland coupler has been used to connect outer armour to the accesory. This provides mechanical protection of the inner cores and a means of earthing of the outer SWA strands.

SWA Cable and Gland Coupler

I now use an adjustable pipe cutter to prepare SWA cable for connection to gland couplings.

Adjustable pipe cutter can be used to prepare SWA cable for termination into a gland coupler.

Two turns to cut outer PVC, then five to ten turns to cut individual SWA strands. This process is much quicker and cleaner than using a hacksaw.

The picture below shows the quality of preparation using an adjustable pipe cutter.


Hand cut SWA using a hacksaw and/or side cutters can be subject to failure due to uneven SWA strand lengths.

SWA cable cut using a hacksaw. Note uneven strand lengths. This makes connection to gland difficult with possible failure of coupling and bonding of SWA strands.

A little extra care and attention in the preparation can make for a much improved and long lasting installation.

Please let me know if you have any tips to improve the standard of electrical installations.


About aimhome
All aspects of energy efficiency and help with saving money spent on utility bills. Home visits undertaken to assess what is used and explain what can be done to save money. Central heating control upgrades, central heating system power flushing. Energy saving lighting surveys and installation of low energy lamps and lighting. Every day that action is not taken is an added cost in hard cash terms. Call today to see what can be done. Green Deal Ecologic Ltd, improving your world without costing the earth.

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