I had a question posed to me the other day and I did not have the answer. I often find older homes with 2 prong outlets. The question was… If the 2 prong was switched out to a 3 prong and multiplier for a computer was used would the electronics be protected properly. I understand that there is no ground back to the panel but would this type of multiplier work?
When using a 2 conductor circuit with 3 prong outlets, a GFCI is the solution.
Gfci breaker at panel or a gfci plug?
Either. If you use the combo receptacle/breaker, put it at the beginning of the circuit in the room and it protects all downstream outlets as well (if you wire it correctly).
Although a GFCI device will make the circuit safer it should not be used as a replacement for grounding. The NEC gives us the “better than nothing” approach of allowing a three prong receptacle on a 2 wire circuit. If the manufacturer requires that the piece of equipment be grounded it should be used as such.
A gfci can never be a substitute for device requiring a safety ground connection.
2 wire circuits are “grounded”, are they not?
Not if it doesn’t have a continuous EGC back to the panel. :roll:
In the context in which it is normally used grounded refers to a grounding conductor or other means not the grounded neutral conductor.
The grounding conductor is provided to protect people if there is a malfunction and provides a path to ground. A GFCI protects people and trips at 4-6 miliamps.
So tell me what is wrong with this statement:
"XX outlets were the 3-prong type and nearly all had no equipment ground. Although an equipment ground isn’t required of 2-prong outlets, if the receptacle is 3 prong and lacks an equipment ground it gives a false sense of safety. Grounding of all 3-prong outlets, reverting back to 2-prong outlets, or protecting them with ground fault circuit interrupters (GFCIs) is recommended for safety reasons. 3-prong outlets that are not actually grounded should be labeled, “no equipment ground”.
A 2 wire system is “grounded”. The neutral is called the “grounded conductor”. Research it.
I don’t think you quite understand this yet. What happens if the neutral becomes disconnected on a branch circuit? Here is a link for you…
Sounds good to me but I would use the word receptacle in place of the word outlet. Also if you wanted to use 3 prong receptacles on an ungrounded system then as you’ve stated GFCI protection and the labels you’ve mentioned are both required.
I understand perfectly. Just disputing your ascertain that the system is not grounded “if it doesn’t have a continuous EGC back to the panel”.
Ok, a two-wire system has a return path to source, but it is not “bonded”, which is what an equipment ground is.
Agreed. My point was that a gfci provides equivalent or better personnel protection than an equipment ground.
Agreed, but only for the human. However, the equipment may be toast if a ground fault occurs.
Some are, some are not a 240 volt circuit would not utilize a grounded conductor. If a piece of equipment is required by the manufacturer to be grounded that is accomplished by a connection to an EGC (grounding conductor) not the grounded conductor but I’m sure that you know that.
Here is a diagram I send to clients. In many cases it is this solution or a complete gut and rewire which is out of the question for most.