We are house hunting for a new home and my fiance loves a house we saw last night. I noticed most of the electrical outlets are two prong instead of three. Checking out our lamps and other electrical equipment at our current townhouse I find that most are two prong devises except our (in my mind) important stuff like the 47" LCD and other home entertainment equipment and computers are three prong connections.

What's involved with turning a two prong outlet into a three prong? I always guessed that the three prong had the extra hold for the ground? Does that mean the two prongers are ungrounded?

I hope this is in the right area and thanks for the replies in advance!

Best thing is to open up an outlet and check (turn the power off at the fuse box first please), but that house could be lacking what is now standard wiring. The only way to fix that is rerun the wire. I would avoid buying a house like that.

Two-prong outlets haven't been installed in ages, which means that the wiring is surely quite old.

In practical terms, that means that you have some additional work ahead of you, but since i love old houses (my first one was 200+ years old and this "new" one is 80+ years old), I wouldn't let that stop you from buying a house you love. Retrofitting wire in a stick-built house is not as hard as a novice might fear, but it is very labor-intensive, so if you're on a budget, you may have to get creative about you split your time to do the time-intensive fishing, etc, versus have an electrician do the final hookups. (Let's face it, if you're asking this question, you shouldn't be doing the final electrical work. No offense, just a practical observation.)

It does however mean that you shouldn't plan on running any power-intensive devices on that old wiring until you get it checked out and probably upgraded. Air conditioners? Hell no. Big TVs? Laser Printers? Halogen lamps? All out.

It's not a matter of just adding a "cheater" plug and plugging your 3-prong power-hungry device into that and making it work. Not safe.

It does however mean that you shouldn't plan on running any power-intensive devices on that old wiring until you get it checked out and probably upgraded. Air conditioners? Hell no. Big TVs? Laser Printers? Halogen lamps? All out.


I think that is taking it a little bit to the extreme. You just have to make sure you don't exceed the capacity of the circuits and the wires in the walls. My Laser printer only draws 2 amps. I can't imagine a 100 watt halogen lamp having any problems. I'm sure there are plenty of old homes with ungrounded outlets that have had window air conditioners running for years.

I grew up in a house with ungrounded plugs. My father had a wood working shop with Table Saw, Lathe, Planer, Drill Press. All ungrounded plugs. Every once and a while you would blow a fuse, no problem you just screwed in a replacement.

I still have the Delta Drill press. It's over 60 years old and runs just fine with the original motor. I keep thinking about putting on a grounded plug but haven't gotten around to it.

We are house hunting for a new home and my fiance loves a house we saw last night. I noticed most of the electrical outlets are two prong instead of three. Checking out our lamps and other electrical equipment at our current townhouse I find that most are two prong devises except our (in my mind) important stuff like the 47" LCD and other home entertainment equipment and computers are three prong connections.

What's involved with turning a two prong outlet into a three prong? I always guessed that the three prong had the extra hold for the ground? Does that mean the two prongers are ungrounded?

I hope this is in the right area and thanks for the replies in advance!


I would investigate the wiring. Is the wiring in 'greenfield' armor or is it in metallic conduit?

If the wiring is in either of the above, chances are that you have a grounded box at each outlet in the form of the outlet box (metallic box?).

If the outlet boxes are metallic, you can probably use a three prong adapter and run the ground wire to the box. I would also have an electrician inspect the wiring for proper connection to the main ground system if applicable.

Yes, the third plug is a hard ground. Two prong plugs have a hot and a neutral, which may not be ground. Some two prong outlets have grounded steel boxes, so they can be converted to three prong. In some cases, grounds can be run to water pipes. This will depend on local codes, so it's a good idea to have a professional do the work or at least look them over.

One danger: if neutral is not ground, putting in some grounded plugs and leaving some ungrounded can be really dangerous. Most of the time neutral can be forced to ground, but this is truly a job for a pro and may require driving grounding rods.

Not the cheapest thing, but worth doing in my opinion.

I think that is taking it a little bit to the extreme. You just have to make sure you don't exceed the capacity of the circuits and the wires in the walls. My Laser printer only draws 2 amps. I can't imagine a 100 watt halogen lamp having any problems. I'm sure there are plenty of old homes with ungrounded outlets that have had window air conditioners running for years.

I grew up in a house with ungrounded plugs. My father had a wood working shop with Table Saw, Lathe, Planer, Drill Press. All ungrounded plugs. Every once and a while you would blow a fuse, no problem you just screwed in a replacement.

I still have the Delta Drill press. It's over 60 years old and runs just fine with the original motor. I keep thinking about putting on a grounded plug but haven't gotten around to it.

I agree. My mother's house is very old with old 2 prong wiring. She had two window AC units running simultaneously for 20 years along with an Oxygen Machine. I'm not saying that he shouldn't rewire, but I agree that the one comment above was extreme.

This comment is extreme? It does however mean that you shouldn't plan on running any power-intensive devices on that old wiring until you get it checked out and probably upgraded

By all means, it's OP's family, not mine, but I don't think getting someone qualified out to check out the known-old and unknown-condition wiring prior to plugging in modern high-current devices is extreme. My advice is free and comes with a double-your-money-back guarantee if you're not satisfied or think it's too extreme... :D

Just as a side note, a 15 amp circuit is a 15 amp circuit, period. Provided that the wiring is still in good condition, there's no reason you cannot run your non-grounded devices safely. Our home was built around 1925-1932 (conflicting documents). All but one circuit has been upgraded over the decades. The one remaining has original, non-grounded knob and tube wiring. I'd still like to replace it some day, but it is only a handful of outlets, such as in the bedrooms upstairs; one TV, a few table lamps, lights, and alarm clocks. I had an electrician inspect it, and he said it all looked terrific. The insulation was in good condition (i.e. not dried or cracked and no signs or overheating). They still sell 2 prong outlets and they're still legal to install in old work.

In a situation like yours, it *is* important to have the wiring evaluated during the inspection prior to purchasing. I'd even go so far as having a qualified electrician inspect it and give you a quote. If the wiring is in good condition, I would only have a couple new circuits run where you need grounded outlets; kitchen(s), bath(s), living room and the garage.

For what it's worth, I'd almost feel safer with a house like that. Too many have had owners that pulled the 2 prong outlets, and simply tied the ground to the box (or worse, an unconnected ground) without knowing whether it was done right or not. This way, you can have things upgraded, and have confidence it was done correctly. Like I said, a 15 amp circuit is safe for 15 amps.... grounded or not... it's when people start monkeying with it or overloading it that wiring gets unsafe.

Unfortunately we did not get the house, another offer was put it so we countered that and beat it but they current homeowners have two mortgages going on the current home and the one they are selling and needed a closing date of September 15th and we couldn't close until October 18th (getting married October 14th)

So while I am disappointed, this thread will help me when find another house we want to put an offer in on. Thanks all.

I *think* greenfield (eg BX) is not suitable as a grounding conductor unless it is less than 6'. Definitely not in new homes.

You can get a third prong by using a GFCI as the first device and replacing the remaining devices with 3-prong outlets. They must be labeled "No Equipment Ground" or some such.

Doesn't sound like that's a task you should undertake. However, I wanted to let you know that the option is out there.

Be sure to read my disclaimer! :)

Tim

Hi, don't mean to hijack the thread (and sorry that you didn't get the house) but this thread comes at a perfect time for me. I just moved into an old (1899) duplex in Wisconsin that has 2 pronged outlets throughout the house (except for the bathroom which has GFCI outlets). We're renting for the year while we look for a house to buy in the area, as we moved from SoCal.

Anyhow, since this is temporary and I do not have the option to rewire the house (the owner is planning on it at a cost of ~15K, yes, very labor intensive) but I do want to setup my home theater system and be relatively confident that surges will not be a problem. We have 2 window air conditioners running constantly, 3 fans, and I've tested with a hair dryer and microwave on as well with no problems. So I don't think that load will be an issue. I guess my question(s) would be, in addition to my surge protection setup, is my only option to get GFCI protection on the outlets or can the cheater plugs properly grounded do the job as well?

Any additional temporary solutions/ideas are greatly appreciated.

Cheers!

I can recall a thread similar t othis one a while back....

My last house was built in the very early 50s. I had an electrician in to replace a non-working 2-prong outlet in the basement that had some scorch marks around it. As I watched him replace it with a grounded outlet, he realized that the builder actually ran 14/2 with a ground throughout the house, and cut all the grounds off EXCEPT in the kitchen, where all (OK, both) of the outlets were grounded to the metal boxes. So he managed to grab the ground with electrician's pliers, twist on a pigtail and install a new three-prong grounded outlet.

I'm guessing it must have been faster and cheaper to run ONE type of wire and to install the 2-prongs except were necessary, so the builder did it the cheapest way. At the time, it probably saved 10 or 15 cents per outlet, but multiplied by every room in 250 houses, I guess it adds up.

After watching him do that, I figured it was easy enough and over the course of the nine years we lived there, everytime we moved furniture and exposed an outlet, I replaced it with a new three prong outlet. It's really not that hard to do. Just be sure to check the new outlet with a tester to be sure you've got it wired correctly.

So, to the OP, if you are looking at older houses, it may be worth checking to see if there is 14/2 WITH a ground already run.

Good luck,
Tom

thanks so much for the replies!

We ended up putting in an offer on another house that was built in 1994 and now I have no more electrical worries. I appreciate all the replies regardless, it's always good to learn something new.

Thanks again.