Just got a new dryer yesterday, and the installation instructions say I need a strain relief for the power cord. Unfortunately, the delivery guys took my old dryer for recycling and only left the cord - no strain relief. Is the strain relief absolutely necessary? Seems they are only sold with new cords, and I'm trying to avoid spending money needlessly.
Yes, for legality and safety. Dryers in particular move a lot, and you don't want your conductors wearing through on the sharp edges of the chassis and electrifying the entire unit or starting a fire.
There's often one built into the dryer. It may be reversed for shipping. Otherwise they're readily available at hardware and home improvement stores for a buck or two.
Strain-relief hardware is readily available at an electrical supply house. This is not a retail store, they are in industrial parks and keep bankers hours, but will happily trade with the public. Except 0-1 cars in the parking lot, no well lit showroom, and a service desk with very knowledgeable staff. Take some photos with your phone and show them.