2-prong electrical outlets in my house. What should I do about them?

September 27, 2015 6:04 PM

Our house, built in the 1960s, has a few rooms where the only outlets are the old two-pronged type. One of these rooms is my office, and the only way I could setup my computer and desk was to use a "cheater" plug to adapt a power strip with 3-prongs to the 2 necessary to plug into the wall's outlet. I have several questions regarding the situation:

1. How much of a priority should it be for me to have an electrician change these two-prong outlets into 3-prong? How much does this typically cost? If the wiring in the house is old is it going to lead to a money-pit of upgrades and work? Can this be done inexpensively?

2. Is it a safety hazard to have the power strip using the cheater adapter? In the case of an actual lightning strike or power surge, would the cheater adapter render the power strip ineffective?

3. Anything else I should know, consider, buy, etc. before/when I talk to an electrician about doing this?

posted by arm426 to Home & Garden (13 answers total)

Where are you located?

A lot of times, updating depends on your municipality - for example, when I lived in Indiana during college, the local fraternity houses couldn't really update their wiring because if they opened any walls they had to bring the entire house up to modern code, so they tended to run new electrical systems on the outsides of walls every decade or so.

Conversely, where I live now (NC), as long as fewer than 50% of my walls are open at any given time, I can perform work piecemeal. We have a crawlspace and an attic so have access to all the wiring except for first floor switches-to-ceiling-lights without opening any walls.

To get to your questions in no particular order:

2. Yes - in case of lightning strike, the 2-prong cheater means any UPS or surge protector will be useless, as there is no ground prong available to shunt the sudden surge into. Whether or not your electrical equipment actually runs into problems during a surge will depend on what path the surge takes through your household wiring.

1. If you're comfortable working with electricity (and respect working with electricity), you can turn off the breaker for that outlet (get a non contact voltage tester like this to verify there is no power), take off the faceplate and pull out the existing 2-prong receptacle to see how many wires (conductors) enter the electrical box. If the existing wire supports it, it is a fairly simple fix to install a 3-prong receptacle.

Watch Youtube videos, etc, or if you have knowledgeable friends (or post photos to Metafilter!) you can ask them.

If you aren't comfortable with electricity, hire an electrician out for consultation on the upgrade - oftentimes they'll work with you to figure out how much work you need and what you can do yourself to save money. This professional can also tell you what kind of wire you have (copper or aluminum) and what kind of upgrades you're looking at. They can likely teach you how to change out the receptacles, which (in most places) doesn't require a permit.

Feel free to memail me if you have more questions or for looking at pictures.
posted by bookdragoness at 6:19 PM on September 27, 2015 [1 favorite]

There are two-to-three adapters.(not recommending amazon--you can get these anywhere.) Remove the screw from the wall plate, plug the item in, and screw back in through the little loop thing (some adapters have a little wire on them--same deal, screw it in)
posted by hexatron at 6:19 PM on September 27, 2015 [1 favorite]

We had a handful of two-prong outlets in our house when we moved in. We were nervous about hiring an electrician and scared we'd learn that our wiring was old and scary, so we procrastinated for a year. Finally when pregnant we pulled the trigger. $800 to update 10 outlets, install one new grounded outlet, and get professional sign off that nothing looked scary. Well worth it.
posted by marmago at 6:55 PM on September 27, 2015

And if the screw isn't grounded, you've accomplished nothing. As Bookdragoness alludes, you need three wires - white/common, black or red 120 v, and green or bare copper ground - or - the two wires can be run inside a grounded covering, which might look like a spirally wound sheath over two single conductors.
Get a cheapy multimeter at the big box store, you should get 120v or thereabouts between the two receptacle prongs. Remove the cover screw and cover and test between the slots in the recept., and the hole where the cover screw screws in. If you don't see 120v or thereabouts, the recept. is ungrounded.
Of you are in a one story building with an attic, it might be possible for an electrician to use the old romex wire to pull a new three conductor piece of romex through the wall w/o opening it and carry it back to your panel box where it can be grounded. If you are on the first floor of a pier and beam house, this can be done through the crawl space.
If I were you, - sensing your level of experience with electrical, I'd get an electrician to come out and evaluate and give you a price for at least getting a grounded outlet to your electronics. It isn't so much a safety hazard as much as it increases the probability of electronics getting fried. When you call, make it clear what you are looking for and that you are prepared to pay for the electrician's time to come out and look at your issue. Most places I know everyone is very busy No one here can give you a price as we can't see what is involved.
Your wiring is not "money pit" old - the only really bad outcome is if it is wired with aluminum wire, which was done for a short while (late 60's to early 70's) until it was found to be a Very Bad Idea.
posted by rudd135 at 6:58 PM on September 27, 2015 [2 favorites]

Most of the time, the reason there are only 2 contacts in the plug is that there are only two wires from the breaker panel. In this case the only real fix is to somehow get a ground wire from your outlet back to the breaker panel. Usually, this means entirely replacing the wiring to the socket.

How expensive this is depends on where the socket is located and on the construction of the house.
posted by mr vino at 6:59 PM on September 27, 2015 [1 favorite]

If I were in your shoes I'd hire an electrician to replace the outlets. If there are only a few without ground, I bet the fix will be relatively easy. I once owned a house built in the 60's and the 2 prong outlets (which was nearly all of them) were actually housed in fully grounded metal enclosures with three strand copper wiring, so I just replaced the old outlets with modern ones. I also took the time to make sure each outlet was fully seated and supported. No more outlets that sank into the enclosure when you went to plug stuff in.
posted by Poldo at 7:05 PM on September 27, 2015

This house, 1958, mostly had 3 prong outlets but they were not real, just ungrounded and installed for convenience. You need to have someone check all of them.
posted by Mr. Yuck at 7:06 PM on September 27, 2015

And it needs to be a physical inspection as those little plug in testers can be fooled by illegal modifications to the electrical system.

You can get most of the safety of a 3 prong outlet on your 2 prong system by installing GFCI receptacles. You just need to install one per circuit if you can identify the first receptacle. The cost is fairly modest and it doesn't require opening up any walls. If the wiring is exposed around the electrical panel you can install a GFCI receptacle right at the panel or a faceless if the circuit is already maxed out.

Note this does not provide an equipment ground. Some electronics need the reference ground to function properly and this won't give you that. If all your stuff is working now though you are probably all right. Most UPS will provide "triangle" surge protection between all three conductors and will therefor provide some surge protection even when plugged into a receptacle that doesn't provide an equipment ground. You could layer that protection with a whole house surge protector installed in your panel.

hexatron: "There are two-to-three adapters.(not recommending amazon--you can get these anywhere.) Remove the screw from the wall plate, plug the item in, and screw back in through the little loop thing "

Note these only work if there is a ground provided to the box (via cable armour, pipe work or an equipment bond conductor).
posted by Mitheral at 8:25 PM on September 27, 2015 [3 favorites]

Our house, built in the 1960s,

Most likely has copper water pipes and copper baseboard heating elements? I'd run a single ground wire from the receptacle to the closest piece of copper pipe and you can't get a better ground than that.
posted by three blind mice at 2:45 AM on September 28, 2015

In our basement, we have two-prong outlets (we're renting, not in a position to upgrade ourselves), and I used a cheater....and I'd get a 'buzz' slight electrical shock if I touched the screen of my computer monitor. The issue isn't just grounding against lightning; it's that the device can build up electrical potential in its internal 'ground', which will want to discharge into anything sufficiently grounded enough, including you, or other electronics that might not tolerate the extra voltage. Don't use a cheater if it doesn't actually provide a ground.

Since I was in the basement, I screwed that little tab on the cheater onto the plug plate, and attached a wire to the same screw so it was touching the tab and I ran the wire to the electrical room where the cable company had added a valid ground so their equipment would survive.
posted by AzraelBrown at 5:41 AM on September 28, 2015

A home we moved out of had ungrounded three prong outlets in a few rooms. This also happened to be all of the outlets in the roomm that we kept some computers etc. Yes, they were all surge protected, and UPS'ed. I went through about 3 power supplies a year, and had periodic deaths of equipment (2 video cards had popped capacitors (one made enough of a mess to also kill the motherboard), 1 motherboard had popped capacitors on it's own, I had a cpu die (I've never had that happen before), and a tablet died while charging). When I finally noticed the state of the outlets, and got them grounded (easier said then done for many of them (I needed to remove the ceiling in the finished basement underneath the room)) I didn't have a single piece of equipment failure in the 1.5 years we lived there after fixing it.

You need grounded outlets in your office. A surge protector/ups can't function effectively if it's not grounded.
posted by nobeagle at 7:47 AM on September 28, 2015 [1 favorite]

As one reference point - - my house is from the early 1960's, and I recently discovered that the original wiring (which runs along the ceiling in my unfinished basement) only has two wires contained within it - - the hot and the neutral. Apparenly, back then, it wasn't standard to include the ground wire..?

This old wiring is sheathed in a brown paper/cardboard material, not the white or yellow plastic that you'll see in today's Romex. So, if your house's original wiring appears anything like mine, there may have no ground wire within it, and therefore, changing to a 3-prong outlet would involve replacing the wiring from the outlet to the breaker box.
posted by see_change at 9:42 AM on September 28, 2015

When I tried to find 2-prong-to-3-prong adaptors at a hardware store, I was told that they're illegal to sell here because it's a fire hazard. The codes may be different in your area, but the level of safety probably isn't. That said, we still used some old adaptors for >5 years and didn't manage to set the house on fire, but your risk tolerance may vary.

I would also be seriously concerned about frying any valuable electronic plugged into a 2-prong outlet. We only used them for things like lamps and toasters, since luckily we did have a few modern outlets installed that we could use for our computers etc.
posted by randomnity at 10:10 AM on September 28, 2015