GFCI on 2 wire systems

Looking for some help on clarification. My understanding is a GFCI will prevent elec shock in a 2 wire system. I have seen them in bathrooms and kitchens. The part that trips me up is, a 2 wire system is still not grounded. That should be a safety concern, but not unsafe with a GFCI installed. (correct?)
Second part of question, in a home with 2 wire outlets why couldn’t a person put GFCIs in all the locations? Like the living room for example. I was ask this question the other day. The occupants would be protected, correct?
Thanks folks.

He can.

I wouldn’t say they prevent, but rather that they reduce the potential for someone to get shocked. People can always find ways to electrocute themselves.

Many older homes’ electrical systems are not grounded, however, short of fully rewiring the house, GFCI can be an effective way of providing improved protection against shocks and maintain “code” compliance with three prong outlets (use the “no equipment ground” stickers).

As Mike said so succinctly, he can install them on most circuits for enhanced protection. Don’t need to install on every outlet, just lead outlet on each circuit. Change the other outlets to three prog, install stickers and he’s good to go.

Of course, I would advise him to use a qualified, licensed electrician to do the work vs. Bubba that handy guy.

They prevent a fault current in excess of 5 mA from going through a person.

That is sufficient to prevent electrocution in most of the population.

Those at risk are ones that have a pathway via inter-venous lines or a compromise layer of skin.

GFCI outlets in non three wire systems need to be labeled appropriately.

Tim a grounded system is to protect the equipt and not you.

Not sure I would want a bunch of GFCI outlets with stickers everywhere that no one will pay attention to when they plug things in.

If this place has real conduit, a switch to grounded outlets is easy.

Conduit in Iowa?

Come on Bob get real.

Do you assume Mike? or have you been there.
I have not.:slight_smile:

For all I know they are using Tesla coils to beam it all through space.

Got relies their Bob.

True, but GFCI’s are not going to protect the 60" Plasma, microwave oven, computer, fridge,…

Never said they were for equipment protection.

Follow the mfgs. instructions for appliances.

I’m sorry, but it really bugs me when people state that GFCI will reduce the risk of (or worse yet - prevent) electrical shocks.


They reduce the risk of death by electrocution, but have absolutly no affect on electrical shocks in general. A 5ma shock is still VERY painful (from what I have read).

Not really

Now 220 kinda bothers you.
110 just tickles.

Have you ever tripped a GFCI with your body (across two fingers doesn’t count)? I don’t recommend trying it, but would be interested in hearing if anyone has.

From what I have heard, at least 220 will knock you off, unlike 110 which just makes your muscles hold tighter.

I have been shocked many times ,so I do not count as I may have built an immunity.

In used to experiment from the time I was a kid.

None the less I would not depend on any devise to always do its job.(haven’t we all inspected bad GFCI)?

Resisting going there. :wink:


I thought I was an electrician .May explain my Einstein hair.

I used to work with a maintence electrician that would wet two fingers and swipe at wire exposed wires to make sure they were dead. :roll:

No different from all the Gas company guys that used matches to check for leaks (OK I was guilty of that one too).

What drives me nuts is how many of the Electricians told me to work live or I was a sissy.

Other than getting scared, I ended up with many bloody knuckles from the kickback.

I have had 440 three phase throw me back when I was an industrial electrician. The flash and the loud pop is unreal. I accidentally bumped some dirt and it fell in the cabinet that I was testing a circuit in. I learned to knock the dust off the panel first before I opened it.
Also once my supervisor was hauled away to the hospital because some water was lying in an electrical panel when he opened the door. I heard the loud pop and I was a good 75 yards away.

I was referring to all of the other possibilities for electrical incidents e.g., miswired (line/load), malfunctioning, people getting shocked at switches, panels, dryer outlets, other devices, etc. People can come up with myriad ways in which to shock themselves. I just don’t like to use absolute terms like “prevent” for these types of things, it can create a false sense of security for the unwitting.