What should you use to connect two pieces of conduit securely?

To ensure a secure connection between two pieces of conduit, using a locknut is appropriate. A locknut is specifically designed to secure threaded fittings and create a tight connection, which is essential for maintaining the integrity of electrical systems. When used in conjunction with a conduit fitting, it helps prevent loosening due to vibration or movement, ensuring that the conduit remains properly aligned and that there are no gaps that could allow moisture or dust to enter.

In contrast, options such as conduit straps and connector sleeves serve different purposes. A conduit strap is used to support and secure conduit to a surface but does not connect pieces together. Wire nuts, meanwhile, are used for making secure connections of wires, not for conduit. Hence, the function of a locknut makes it the most suitable choice for connecting pieces of conduit securely.