This eliminates the possibility for a ground current traveling to the machine, as it features a separate return path for unused power. The more recent 4-prong dryer cords feature two hot wires, a neutral wire and a ground wire. If a current happened to make its way onto the ground wire, it could travel up to the dryer. 3-prong dryer cords contain two ‘hot’ wires along with a third wire that contained both the ground and neutral wire. So, why did the NEC make the decision to switch from 3-prong to 4-prong dryer outlets in new homes? Although the old 3-prong outlets were effective at providing power to dryers, they had one major flaw: the ground and neutral wires were grouped together, creating the potential for shock. Existing homes may still use 3-prong outlets, as the NEC changes are limited strictly to new homes. It wasn’t until 1996 when the National Electrical Code (NEC) was updated to require 4-prong dryer outlets in all new homes. Nearly all homes built before this time featured either a 3-prong outlet or range outlet (slightly different than a typical 3-prong dryer outlet). Up until the mid-1990s, 3-prong outlets were the standard used in American homes. In an effort to shed some light on this subject, we’re going to discuss the purpose of these cords and why there’s a growing popularity for 4-prong cables. Unfortunately, few people understand the difference between 3-prong and 4-prong dryer cords. Whether you move into a new home that has a different outlet or purchase a new dryer with a different power cord, this is an all-too-common scenario. For example 14-50R becomes 14-50 receptacle or 14-50 outlet.Most homeowners have run into a problem with trying to hook a 3-prong dryer cord up to a 4-prong outlet, or vice-versa, at one point or another. The R stands for Receptacle (outlet) and the P stands for Plug, we commonly truncate this to just the numbers and add the word receptacle (or outlet) at the end. In the full NEMA number you will see a capital R or P. Be sure to carefully look at your outlet and the chart, it's easy to mistake one outlet for another if your outlet has it's ground pin facing the floor instead of the ceiling or Vice Versa compared to the chart. 110/120 volt outlets can be found mounted in all directions. L6-30 (locking 240 volt 30amp) Twist-Lock 30A 240 volt outlet, my personal favorite locking connector, easy to find in stores, works great for adding adapters to portables EVSE’s equipped with a L6-30 plug.Ģ20/240 volt outlets are commonly install with the ground pin towards the ceiling for safety.TT-30 (Travel Trailer 30amp) 30A 120 volt 3-prong outlet, the older style found in RV parks, not used in residential homes. This is the one the Tesla guys install in their garages. By far the best universal connector to have for an EVSE.
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