2 prong and 3 prong?

Hi Electrical gurus,

This house was built in the 60’s when 3 prong outlets didn’t exist. But what about when the house has some 3 prong added also?? I was under the assumption the 3 prong additions were not proper when the rest of the house had 2 prong. Help? Opinions?


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Are they grounded? If they are grounded properly they are fine.


**The use of three-hole ground-type receptacles on a two-wire electrical system gives the impression that safety protection is present in the circuit, when in reality it is not. Older style two-hole receptacles are still available and should be installed to eliminate this false sense of security. Three-hole receptacles may be more convenient (and often less expensive), but are often installed without giving consideration to this situation. **
**The use of a three-pronged plug in an ungrounded receptacle can be a safety concern. The plug has the grounding provision for a reason and electrical appliances should always be used for the function they were intended to perform. **
**All such installations should be labeled “No Equipment Ground” on each receptacle that applies. **Grounding of all “three-pronged” receptacles or protection with a Ground Fault Circuit Interrupter (GFCI) on each is recommended for safety reasons, prior to the close of escrow or after taking possession of the property.

**“Two-hole” outlets are not grounded and should never be used with a “three-pronged” plug. Adapters have been devised for this usage, but there is still no adequate ground and such adapters are not always safe. Until the electrical system is upgraded for “three-pronged” usage, it would be prudent to not use adapters, extension cords, or “three-pronged” plugs in any way. Consider that “three-pronged” plugs have been engineered for use with a “three-hole” grounded receptacle. **

Check for a ground, I had a neighbor upgrade all his two prongs to three after he established his boxes were grounded, via AC.


You just have to dig a little deeper into the system. One can not assume that just because one room a home has two prong ungrounded circuits that all of the the rooms do. It is not uncommon to find homes that have been upgraded at some time to have part of the home grounded while some is not. I find many where the kitchen, or a converted garage, etc. has 3 prong receptacles and is in fact grounded while the remainder of the home is not. This is one reason many HI use a little more sophisticated circuit tester. If it is a two prong outlet, I use a voltage detector to see if it does have power and to the correct side. Doesn’t take any extra time to scratch below the surface. Be aware that many older homes have wall receptacles serviced through a wall switch. If there is not a ceiling light/fixture look for this.