Working with shielded cable: what to do and what not to do

Shielded cable is an electrical wiring solution where the ground, neutral and positive wires are encased in a flexible metal jacket. 

It is much more durable and resistant to damage than non-metallic or Romex wire and is approved for many more types of construction applications. 

Although shielded cable is stronger than NM cable, it is also more difficult to work with. 

So here are some do’s and don’ts of working with shielded cable that will make the job easier and more successful.

Do: buy a shielded cable cutter

If you want to make clean cuts on the shielded cable, you need to invest \$ 30- \$ 40 and buy a specialized tool for cutting shielded cables.

 Although this will slightly increase the overall cost of your project, it will be able to quickly cut through the tough metal casing on the shielded cable and will reduce the time required to install the cable.

No: use a saw to cut the shielded cable

Many people choose to use a hacksaw or other cutting tool to cut the shielded cable. 

While this is possible, I strongly recommended that you do not attempt it. 

When shielded cable is cut with a hacksaw or other cutting tool, it can produce rough or jagged edges that could damage the insulation of the shielded cable or even cut electrical wires inside the metal jacket. 

Notched cables within shielded cable create a dangerous fire hazard. Check out the first tip in this article and understand a shielded cable cutter.

Do: I always use anti-chaff bushings

Anti-short bushings are plastic funnel-type elements that are inserted at the end of the shielded cable. 

The rounded edges of the anti-short bushings help prevent nicks and cuts to the electrical cable within the sheathing and also help to better insulate the wiring to avoid arcing or short circuits.

 Never attempt to install a shielded cable without using anti-short bushings.

No: just hand-tighten the locknuts

When connecting the shielded cable to the junction box, you may be tempted to hand-tighten the locknut on the threaded portion of the shielded cable connector. 

However, you should always use a flathead screwdriver and hammer to tap the locknut until it is tightened securely. 

If you don’t, the locknut can move overtime for free and cause a short in your voting system wiring. 

In extreme cases, your cable can fall completely out of the junction box and create a very dangerous fire hazard.

Do: I always use armored cable support straps

When installing the shielded cable, place support straps every 24 inches to ensure that the weight of the cable is fully compatible. 

Long lengths of shielded cable can be quite heavy and cause strain on the connector between the cable and the junction box if it is not compatible.

 You should also attach a support strap within about 12 inches of the junction box. 

The last thing you want is for the weight of the shielded cable to cause the connector to fail and allow the cable to fall out of the junction box.

 

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