Strain reliefs protect electrical cords and various cables and tubes by absorbing pulls and twists. A strain relief is sometimes short and rigid, but other times it includes a long flexible portion, called an over-mold, like the kind you'd find on a vacuum cleaner. Some strain reliefs attach mid-line, but most attach at the end to reinforce the connection between wire or cables and equipment.

When shopping for strain reliefs you have various options, like nylon or metal, knockout or threaded, and dome or flex. You'll also want to find a decent match to the color of your cord or equipment. Here are a few other important strain relief parameters:

1. Diameter of wire or cable that the strain relief will accommodate.

2. Temperature range in which the strain relief will operate properly.

3. Type of integral clamp that secures the strain relief in place.

Action Steps
The best contacts and resources to help you get it done

Buy strain reliefs that suit your application

You may look for a strain relief connector, cable strain relief, wire strain relief or even a rubber strain relief. In addition some types that have O-rings, as apposed to seal; and some types that have knockouts, as opposed to threads. Manufacturers that have wide selections can be a huge help when it comes to finding exactly the right part.

I recommend: Estco Enterprises, Inc. carries a wide range of cable and some wire accessories and products, including large selections of nickel plated and nylon strain reliefs. If you are looking for mid-line strain reliefs or right angle strain reliefs, then Bolt Products, Inc. is a great place to look. They have a huge variety of products.

Look for a standards rating when you shop for an electrical strain relief

Underwriters Laboratories, or UL, may be the most common type of approval. The UL Listing Mark means that a product tests at the UL published standards. The UL Recognized Component Mark is different; essentially, it denotes that a product is only one part of a whole system and may or may not perform at the usual UL standards. Also look for CSA, the mark from the Canadian Standards Association. NRTL/C denotes certification in both the U.S. and Canada.

I recommend: Take a look at the products from Lapp USA. You'll notice that along with their product diagrams and technical data, they publish both CLA and UL marks, as well as other standards marks. Sealcon USA goes as far as to publish their approval certificates from various standards institutions for their strain reliefs and other products, including UL, CSA and many others.

Replace a worn cord strain relief with a similar part

To replace damaged strain reliefs, look for companies that clearly publish their product specifications. This will help you locate the right replacement part quickly.

I recommend: So-Cal carries a nice selection of solid or ribbed strain reliefs, each with clearly published dimensions for round, square or even rectangular shapes. If you are looking to replace liquid tight strain reliefs, Major Electronics Corporation carries a wide variety in various materials and types, including flex and dome strain reliefs.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Strain reliefs connect wire or cable to devises, but the over-mold portion of a strain relief alone can increase pull force tolerance by over 40 pounds.