The Difference Between a 3-Prong and 4-Prong Plug

If you have recently purchased a new dryer, dishwasher, or other large appliance, you may have run into a slight hitch during installation. This is especially true if you live in an older house.

Actually, if you live in an older house, you may have run into several slight hitches as you attempted to install modern large appliances, but today we are focusing on one.

Order homes generally weren’t built to handle the amount of electricity needed to power today’s large appliances.

And importantly comment they didn’t have the safety features necessary to make sure these large appliances don’t pose a risk to your house and family members.

Traditional vs modern grounding

In order to safely operate, appliances need a grounding wire. This is a dedicated wire to deal with a surplus charge that could be created by exposure to water, a burst of electricity, or a lightning strike. The job of the grounding wire is to allow that Surplus electricity to travel quickly to the ground.

This is where electricity wants to go anyway. The grounding wire just makes sure that it – and not you – is the fastest way for the extra electricity to get to the ground. Thus the primary purpose of a grounding wire is to prevent people from being electrocuted.

Grounding wires also prevent sparking and house fires.

But if the 3-prong plug does that … why do I need 4?

So you might ask, if a three-prong plug has a grounding wire why do I need four prongs?

The 4-prong setup allows multiple advantages. The 4 prong plug has a positive and negative prong, a ground prong, AND a neutral prong. This allows it to not only safely carry Surplus charge to the ground, but also to protect the appliance from those excess charges.

The neutral wire also allows the cord to safely carry higher voltage to your large appliance, and is used in appliances where electricity is being turned into heat. Creating heat is generally an inefficient practice and takes larger amounts of electricity than other applications, so the extra layers of safety are necessary to prevent damage to the house, the power lines, and to users, and to prevent overheating, sparking, and possibly fires in the event that something goes wrong.