It's Electric!

February 13, 2005 8:07 PM

The outlets in my new apartment are two pronged. I've been tearing the third prong off of power strips in order to plug them into the wall. Is this bad?
posted by tomharpel to home & garden (18 comments total)

oh geez dude. yes bad. at the very least you're being destructive with your stuff needlessly. go pickup a batch of these puppies and go crazy.
posted by glenwood at 8:20 PM on February 13, 2005

Dear God it's bad.
The least you can do is get a converter that allows you to plug in a three prong plug to a two prong plug with a grounding thingie. Unscrew the wall plate slightly, put the thingie under the screw, tighten it back and (if you're lucky) you'll have the grounding you need.
posted by nj_subgenius at 8:20 PM on February 13, 2005

It's not a good idea, and it's especially bad if the appliances you're attaching to the power strips are three-pronged. The grounding wire is there for a reason, and you could do damage to your equipment (and yourself) if you don't ground the things that are built with grounding capability.

It might not require a rewire though -- if you feel up to it, cut the power at the breaker and remove the faceplate, and see if there's any ground behind the plate. If there is, you can buy a three-pronged plate and hook up the ground.

If you're at all squeamish about this, get an electrician (or your landlord, if you're a renter and he/she is nice) to check it out.
posted by aberrant at 8:21 PM on February 13, 2005

It's probably better to get two-pronged adapters. They aren't that expensive--something like 79 cents for a pair, last time I bought any. I don't think you're going to cause a fire or anything, though.
posted by goatdog at 8:21 PM on February 13, 2005

(Shows what I know.)
posted by goatdog at 8:22 PM on February 13, 2005

Yes. This article explains how to convert the outlets.
posted by MLIS at 8:23 PM on February 13, 2005

What everyone else has said. Go to Home Depot and get some new power strips and some three-prong to two-prong adapters. They're like eighty-nine cents each and less likely to burn your apartment down.
posted by makonan at 8:24 PM on February 13, 2005

nj_subgenius: not a good idea to just attach the ground wire to the faceplate screw unless you're absolutely sure that you've got a reliable ground behind the faceplate -- otherwise, you could do some major damage, including starting an electrical fire.
posted by aberrant at 8:24 PM on February 13, 2005

Makonan's link is good, but if you use GFIs, make sure you test them periodically, especially if you're using them in a place that gets moisture, dirt, dust, etc. You've seen these outlets before: they have the "test" and "reset" buttons on them.
posted by aberrant at 8:27 PM on February 13, 2005

It's not good to use a 3 prong device in a 2 prong outlet, whether or not you use an adaptor. The adaptors really don't protect you, they just keep you from having to remove the prong. Most adaptors have a way to ground the plug but you have to actually do something to make it happen, and generally you have to know what you're doing.

Under normal operation, the ground wire is generally not used, and does not carry current. National code, in fact, forbids it to carry current under normal conditions. However, in the event of a fault in the equipment, the ground line is there to provide a place for current to go, essentially to keep there from being a voltage drop between exposed metal parts of devices, and, well, the ground (i.e. you usually).

Some devices do not have a grounding connection on the plug. These are usually double insulated and certified to not cause eletrical shocks even under faults that might be expected.

There is a risk of fire with a device that has a grounding plug not being grounded. I don't know how great the risk is, but it exists. The fact that a device works with the ground defeated doesn't mean that it's safe.

There are some nice books that explain the electrical code, that are fairly light reading. I'd recommend it for anyone who needs to do more that, say, replace an outlet or a light switch (and maybe even for doing that. It's not actually that obvious how to wire stuff, or even which direction to apply wires, how much insulation to strip (and how), etc. I'm kind of a nerd but I worked my way through one of the code explanation books in a couple of days.
posted by RustyBrooks at 9:32 PM on February 13, 2005

fwiw, me and my 3 prong outlet stuff survived 2 prong outlets (using the adaptors). I'm not saying its safe or wise, just saying I did it and made it through without any problems.
posted by forforf at 11:34 PM on February 13, 2005

The risks of pulling the prong on a power bar are pretty straight forward.

1) If you use only two prong devices you can be sure that everything will work exactly as intended.

2) If you use three prong devices you are forgoing any added protection grounding offers, and you are probably making yourself liable if bad things happen.

In the case of 1) above you must be sure that nobody can inadvertently plug a three prong device in. They would naturally assume that the third prong was functional, and that would be bad. So, jam some plastic in the third prong hole to prevent use. In the case of 2)... Well, this is where it gets hairy, of course.

If you are looking for permission to not use the third prong you aren't going to get it here. However, people have been ignoring the third prong for many years, and some of them have survived...

It must be terribly inconvenient for you, so I will try to elaborate. I can think of five possible implications of removing the ground, and related consequences:

1) To the best of my knowledge the third prong is intended for electrocution protection only. Several sources state that it is intended for use whenever a device has exposed metal, to guarante that said metal is not 'hot'. I think I have used devices with no exposed metal that still had a ground, which raises some questions in my mind about those sources....

2) RustyBrooks pointed out that it is possible certain devices count on earth ground as a part of internal fire prevention measures. I'm not sure if safety standards such as CSA UL and CE allow manufacturers to assume that ground is functional when testing for fire hazard. It is worth noting that as far as I can tell safety agency approval voluntary in the USA and Canada, CE approval is required for devices sold in Europe.

3) MLIS's handymanUSA link points out that surge protectors sometimes/always(?) count on earth ground to provide surge suppression. If you don't have a surge protector or you care more about using a device than you do about having it protected from surges then you obviously don't need to worry about this.

4) Some devices may have electro magnetic interference (EMI) shielding that counts on earth ground. The worst case is that the device won't work properly, something you can deal with when you come to it.

5) Many devices have internal transformers that provide electrical isolation. Sometimes the third prong ground removes that isolation, and that is sometimes undesirable. I would sometimes lift the ground on my TDS210 oscilloscope because to isolate the probes ground clip from earth ground. Some audiophiles will lift ground on electronics because it can form a ground loop, which causes electrical interference.

How to proceed...

The handymanUSA link correctly points out that electrocution hazard can be taken care of pretty thoroughly by use of ground fault interrupters. Unfortunately the handymanUSA link also suggests several ways to replace a two prong outlet with a three pronged ones. I don't trust their methodology, and I would never do the replacement unless I was upgrading to a GFI outlet. Even then, I would probably jam something in the third prong hole so that nobody could mistake it for a functioning ground.

Finally, if you are going to run devices that should be grounded without ground, do it one device at a time. Disable all female ground connectors on every power bar and every GFI outlet you add. You don't want anybody assuming ground is going to be working, and have them find out otherwise the hard way.

Sources and additional reading:
A good starting point at HowStuffWorks, but you should read some of the other articles too. And a good Wikipedia article.

Well, it is a lot more complicated than I thought it would be when I started... Feedback welcome.
posted by Chuckles at 11:46 PM on February 13, 2005

I must learn to proofread more effectively. ARGH!
posted by Chuckles at 11:49 PM on February 13, 2005

RE: GFI outlets - you can protect every outlet on a single circuit with a GFI circuit breaker. This was done for lighting in wet locations in our new addition.

To test your existing system, you can buy a simple tester for $3.99 or so. It has a series of LEDs. It will show open ground, open neutral, neutral/hot switched, neutral and ground switched(!) and normal operation. Pretty handy when looking at real estate or maybe demonstrating to a recalcitrant landlord that you do have a problem.
posted by fixedgear at 1:55 AM on February 14, 2005

Some GFIs will pop off fine when you hit the test button, even without a viable ground. The same guys who make fixedgear's thing also make a thing that leaks a little current across to ground and drop it, which is the right way to test them. Woodhead used to be good, brand-wise, and not much more than the cheap ones.
posted by unrepentanthippie at 5:21 AM on February 14, 2005

unrepentanthippie made me think more about it (apparently that is possible)... If you are connecting two devices to the same GFI, and you are touching both devices, and they both have a fault allowing live/neutral to touch the chassis, then you will get shocked. The GFI won't do anything. However, if they were connected to two separate GFIs you would be protected...

So GFI doesn't help much except in the bathroom, kitchen, utility room, and outside (anyplace you are likely to come in contact with ground, which is to say plumbing, structural steel, wet earth...). That would be why they are recommended in those locations, duh!

This doesn't really help with the original question though...

What are the three pronged devices being used, and what rooms are they used in?
posted by Chuckles at 7:43 AM on February 14, 2005

4) Some devices may have electro magnetic interference (EMI) shielding that counts on earth ground. The worst case is that the device won't work properly, something you can deal with when you come to it.

"Won't work properly" can mean that you hear a buzz or hum through your speakers on audio equipment or televisions.

IF you adapt down to two prongs, AND you happen to plug them in upside down (so the polarity reverses), any exposed metal could be HOT (i.e. you are connected to 120 Volts AC if you touch the device). My brother got electrocuted on a refrigerator that way (he survived but has been a little edgy ever since!) That's why they make one blade of the plug slightly wider than the other- to prevent this. But if the plugs in the wall are worn, the wide blade can conceivably fit into the narrow hole.
posted by Doohickie at 8:54 AM on February 14, 2005

Doohickie, That refrigerator must have had a fault. Specifically, the neutral must have been improperly connected to the chassis.

CodeCheck is always a good source for this type of information, I should have checked them earlier. Here is their article on replacing 2 prong receptacles. It doesn't really say anything different from the handymanUSA site but it is much more precise, which is nice.

I think I scared tomharpel off :P
posted by Chuckles at 12:51 AM on February 15, 2005