1) Do two prong outlets have to be grounded?

Not necessarily. The installation conforms to code if the circuit is protected by a GFCI. Also, the installation is generally legal if it conformed to code at the time it was installed, providing that it has not been altered in the meantime.

2. Do two prong outlets have to be correctly poled?

Absolutely. If the polarity of the outlet was incorrect, and you can show that the reversed polarity damaged your computer, then you have a case against your landlord.

3. Must they install three prong outlets?

No; in general, it is not required to upgrade existing installations to meet revised codes. If the two-prong outlets were code at the time they were installed, then they are still permissible. In fact, installation of 3-prong outlets on an ungrounded circuit is impermissible unless a GFCI is installed to protect the circuit.

4. Must they correct the circuit breaker amperage rating problem?

Yes. That cannot possibly have been code at the time of installation (unless the installation is really seriously old, like maybe 100 years.)

5. Will the necessary repairs make it possible for me to plug in my computer there?

You can plug it in and it will power up, but without a ground, the surge protector will not perform any protection function.

Wow thanks a lot for the lightening quick response.

Am I right in thinking that in the course of correcting the reversed polarity problem/circuit breaker problem they must also correct the grounding problem or install a GFCI in the circuit, since an alteration is being done?

I appreciate the help.

They should correct the reversed polarity and circuit breaker problem, but they do not have to correct the grounding. They have the option of replacing the two prong receptacle with a new two prong or replacing it with a GFCI receptacle (or making the circuit GFCI protected) and labeling the receptacle as "no equipment ground". To properly ground this receptacle would, in my opinion, not be required.

no they are not required to fix the grounding (its not technically a problem). Reverse polarity simply means that either on the outlet or one somewhere upstream the wires are connected to the wrong screws.

The reversed polarity should be corrected. However, I will stick my neck out here and say that I doubt that your computer was damaged by reverse polarity.

If your description of the circumstances is complete and accurate, I'd say that the computer failure was coincidental. There is no justification for blaming the landlord, and IMO he should not have to pay for repairs to your computer.

The landlord should have the problems with the breaker and the polarity repaired in order to comply with code, however.

Hi davidr,

I'm curious, on what basis do you think it's coincidental? I think it's extremely unlikely that a short suddenly appeared in my power supply that caused sparks to fly out of there (it had just been tested ~12 hours earlier. It's much more likely that the reversed polarity just wasn't appropriate for the computer power supply.

I'm going to buy a new power supply, and I'm praying that none of the other computer components are damaged.

It does seem unlikely to me that this would cause the failure esp as dramatic as you describe.

The term "polarity" is a misnomer. By its very nature, alternating current as provided by a 120 volt receptacle doesn't have polarity.

So-called "polarity" in this context refers to the fact that one side of a 120 volt receptacle is grounded (neutral), and the other side is hot (not grounded). These are related to safety and shock protection, not to preventing damage to an appliance.

(BTW, the "polarized" plug is a relatively new development. As recently as 25-30 years ago, 120 volt plugs could be inserted either way.)

Anyway, to cut to the chase, there is no mechanism in a hot-neutral reversal to cause the symptoms you described. Sorry.

Good luck with the computer, and make sure your landlord takes care of that circuit.

My knowledge of the "workings" of computers is limited. But I agree with DavidR that the reverse wired receptacle would not cause an electrical problem for equipment. Under some circumstances, it could pose a safety hazard for people.

I understand about the polarity definition & AC davidr.

There's a discussion of this topic here: http://forums.mikeholt.com/showthread.php?t=68736&page=3

Apparently some circuits in electronics are affected by reverse polarity, if they somehow connect neutral and ground.

Of course, a simple experiment would work. Take your desktop computer, reverse live and neutral on the lines, and see what happens (hopefully you'll still be posting :-)

Talk about errorsÂ

1) Do two prong outlets have to be grounded?
Not necessarily. The installation conforms to code if the circuit is protected by a GFCI. Also, the installation is generally legal if it conformed to code at the time it was installed, providing that it has not been altered in the meantime.
A 2 prong outlet by definition does not have aground present.
2) Do two prong outlets have to be correctly poled?
Absolutely. If the polarity of the outlet was incorrect, and you can show that the reversed polarity damaged your computer, then you have a case against your landlord.

Polarity was not required until recently. A 2 prong outlet with equal sized prongs is NOT polarized. If one blade opening is larger it should be polarized.
3) Must they install three prong outlets?
No; in general, it is not required to upgrade existing installations to meet revised codes. If the two-prong outlets were code at the time they were installed, then they are still permissible. In fact, installation of 3-prong outlets on an ungrounded circuit is impermissible unless a GFCI is installed to protect the circuit.
This is only half correct.
A 3 prong receptacle is allowed if protected by a GFCI, but the stickers in the GFCI box MUST bew affixed to every outlet downstream. ÂGFCI protected and ÂNo groundÂ.
4) Must they correct the circuit breaker amperage rating problem?
Yes. That cannot possibly have been code at the time of installation (unless the installation is really seriously old, like maybe 100 years.)
Knob & tube wiring did NOT follow te existing wire sizes. Even the requirement that #14 wire be limited to 15 amps, and #12 to 20 amps, are relatively new rules.
5) Will the necessary repairs make it possible for me to plug in my computer there?
You can plug it in and it will power up, but without a ground, the surge protector will not perform any protection function.
A surge protector will provide line to line protection without a ground.
It will NOT provide line to ground protection without a ground.

A swapped line-neutral will NOT cause any modern electronics to fail.

Everybody seems so sure that the swapped live/neutral could not have caused the problem. Have you guys actually tested this out?

I was somewhat joking before, but really - could one of you swap live and neutral on the line to your desktop computer, and tell me what happens?

I would say the fact that you used a "converter" to go from a 3 prong plug to a 2 prong receptacle cost you any chance of recovery of damages to your computer. If the 3 prong receptacle you first used has been upgraded to include a proper grounding circuit, then that is the one I would stick with. Otherwise, you are going to have to convince the landlord to upgrade the wiring in the entire house (should be done and he knows it) or move to another house.

I don't think the swap live/neutral is a big deal.
I have a bunch of computer power cords that I pulled the ground plug off of (used to live in old house with no ground...and ran out of cheater plugs). I use those regularly in my new house. I make no effort to correctly plug where the ground SHOULD be. These plugs are not polarized...as the grounding conductor would have that same affect.

I've lived in old houses where, prior to upgrading the wiring, I plugged computers into 2-pin, nonpolarized recepts. There was actually one case where, for a few weeks, I had to use a plug body in a ceiling light - the only outlet in the room! (Don't try this at home. ;-)

In the 23 years I've used home computers, I've had only 3 computer PSes fail. Concidentally, they were connected to properly grounded and properly "polarized" circuits. I suspect that the reason they failed is that they were all the typical low-budget PSes that you get in $30 computer cases. (Don't try this at home, either.)

Everybody seems so sure that the swapped live/neutral could not have caused the problem. Have you guys actually tested this out?
I was somewhat joking before, but really - could one of you swap live and neutral on the line to your desktop computer, and tell me what happens?

i have done this many times, it WILL NOT harm a power supply. when we run sound at concerts and such many times the supplied electrical feed will have a hum on it due to ground potential, especially in older venues. we use a 2 prong adapter with the neutral blade ground down so that we can reverse it in an outlet. the computer, mixer boards, effects boxes and power amps all work just fine. though this is not recommended, nor legal, for permanent use, in our case it is a requiremenet of the job.

i suspect the power supply just failed. the FIRST clue to this is that it was "about a minute after" you plugged it up. if the miswired outlet were the cause, it would have fried instantly.

Carefull, I remember from somewhere a church minister got killed touching his lips to a microphone on stage. The board had the ground lifted and their was a ground fault to the shielding of the system.

i have seen nasty shocks before on sound equipment. our stuff is checked before use to make sure there is no problems with the setup. if we detect voltage, we make them find the problem and fix it before anyone can use the system. but for a simple ground hum we just use the reverse polarity to clear it.

Isn't the center screw on an 2 prong outlet the equivalent of ground/neutral (inside the receptacle they are wired together)? On the 3 prong adapters, you have a prong that comes out of the bottom of the adapter ground lug to attach to this screw for grounding purposes (see link at the bottom for a picture of what I'm talking about).

Follow me here...If the plug is wired with reverse polarity, then the center screw is live. The ground wire on a PC screws directly to the metal case of the power supply, which in turn connects to the metal case that connects every other part inside the PC to this ground lug.

In this scenario, the case of the power supply (and subsequently the PC) is live.

While I will agree that reverse polarity is fine, but only if you were to reverse the 2 wires. With this 3 prong adapter, we have 3 wires reversed: The hot has become neutral, the neutral has become hot, and the ground lead has become hot. This would equate to a direct short in the PC power supply.

With a 3 prong receptacle that has been wired in reverse, the hot becomes neutral, the neutral becomes hot, and the ground stays ground. No problem here...PC will still work fine.

I disagree that this was coincidence. I have seen many power supplies go, and they can be graceful...but they can also be violent with sparks and even flames.

Here is a link that might be useful: Grounding adapter

"Isn't the center screw on an 2 prong outlet the equivalent of ground/neutral (inside the receptacle they are wired together)?"

No, the yoke of a receptacle is not connected to the neutral, except when it is a 3 prong receptacle with a "bootleg" ground. The neutral, just like the hot, must always be insulated from all other metal parts all the way to the service entrance.

The only time I have ever seen a power supply fry was when it accidentally got 240 volts.