US House wiring question

No tricks, just a regular old house in the US, call t a 200 amp service, 15 or 20 amp circuit.

What are the potential problems with reversing the polarity of outlets?

Outlets with reversed polarity are generally harmless* to the house itself, but they can and will damage certain equipment plugged into them - those with a polarized plug - one prong larger than the other.

*in and of themselves they are harmless, but under use and under load may cause issues/damage.

It will mean that a device with a polarized plug won’t be as safe to use.

Generally speaking, it’s not a huge deal. But for maximum safety the receptacle should be wired correctly.

could be fatal. it could start fires.

it is one of those all depends on many things. if the hot and neutral conductors were reversed then the outside of some electrical devices could have the hot electrical voltage on it. the screw threads of a twist in light bulbs would have the hot electrical voltage on it. if you contact that hot electrical voltage, depends on conditions, you could die or be injured.

electrical devices could be damaged and cause fires.

correcting it is an important and easy remedy.

I understand the threaded part of a light bulb socket is connected to neutral. But I am not aware of any appliance or device where the metal chassis is connected to neutral. I have always been under the impression that it would be illegal to do this. Please correct me if I am wrong.

As far as device cases are concerned, I believe they’re always connected to ground, not neutral.

The US House holds elections every two years. It is not uncommon for the majority and minority powers to reverse, often in rancorous, polarizing times. Regardless of which party holds the majority, increased polarity can undo or override previous legislation passed by a more moderate chamber–paradoxically imposing the will of a smaller minority on the country as a whole. Risks include loss of recent electoral gains, deadlock, and further polarization of people’s views.

I’m disappointed that you didn’t make a joke about Speakers.

You also run the risk of damaging any electronics, appliances, etc. that have polarized plugs.
As johnpost says, depending on circumstances, you could have a fire or be electrocuted, since parts may be energized.
For example, your toaster uses a switch to interrupt power to its element, with a reversed polarity, the element is energized even when it is off and cold.
Years ago I ran into some electrical baseboard heaters that gave me a little bit of a shock.

The solution is extremely simple, get it fixed ASAP.
FTR, whether you rent or own, everyone should have one of these. They are inexpensive and could save you big bucks, if not your life.


It’s because I was distracted by the sequential threads:
US House wiring question
Why is our House of Representatives fixed at 435 members?

It just occurred to me that every wiring project I’ve done in our house over the past five years has been done with the help of the SDMB–and most of the contributors are in this thread too. From new outlets to a garbage disposer to, yes, speakers, nothing ever gets done without checking in here. Thanks!

I do not understand how a reversal of polarity can cause a device or appliance to become damaged. Could you elaborate on this? As far as I can tell, the biggest risk of polarity reversal is to human safety. (Devices with polarized plugs usually have a power switch, and the power switch is connected to the power cord’s hot conductor. When plugged in to a properly-wired receptacle, flipping the device’s switch to the “off” position will keep the device’s internal wiring & circuitry at ground potential, thereby making it safer in an overall sense.)

It was an ohmage.

Electric dryers and ranges wired with the older NEMA 10- plug/receptacle connect neutral to the chassis.

Or a response to current events.

Actually, I was trying to remain neutral.

Good to know. But those are 220v applicances, right?

I worked construction for a couple years when I was younger and was witness to 2 deaths on the job. One, a roofer fell off a 3 story beach house trying to climb down an extension ladder, and the other was a plumber that was electrocuted because the hot and the neutral were switched.

Basically the house was in the trimming out stage and the painters wanted spot lights around the house to shine on the walls. Rather than drag around power cords pulling form the temporary power poles they ran a cord and lugged it into the meter base. Not legal at all! The electricians had already cut everything in, so the cord pushed power through the meter socket, into the panel, and distributed it to the receptacles. Now the painters could just plug their lights into any receptacle in the house. Problem was the feed cord to the meter base was plugged in backwards. It reversed the polarity and sent power down the neutral line. On a 200 amp service (at the time, might be different now) inside the panel the neutral and ground wires lug into the same bar. This made anything grounded in the house hot.

A plumber under the house running the drainage tried to slide underneath a metal HVAC trunk line. The trunking was grounded and therefore hot. It was middle of summer, so he was sweating a decent amount. Plus he was perfectly grounded….his back was pressed to the earth! Having your equipment grounded is good, a human grounded is bad. The current ran right through and he was pinned under the AC trunk. He died on 120v. Very sad.

I spent 5 years doing construction and I’m glad that I made it out unscathed. It seemed like everyone I worked with had at least one really near death experience.

The purpose of polarized plugs is safety.
It’s rare with today’s electronics due to the use of the use of diode bridges, rectifiers, etc. to protect against it, there is still the potential to cause damage.
For example, electric motors and voltage regulators are especially vulnerable to reverse polarity.

In the “Age of Recalls”, I would never, knowingly, plug something in with its polarity reversed and assume that it’s OK.

Yes, I agree. But you said reverse polarity could also “run the risk of damaging any electronics, appliances.” I’m just wondering how reverse polarity could possibly damage a device.

If they’re strictly 120 VAC, single-phase devices, why would they care about polarity?

As for old dryers and ranges, I wasn’t aware they connected the chassis to neutral. A break anywhere in the neutral wiring, therefore, could render the chassis hot. :eek:

I think it once was common. Like some other things, it was banned after it killed enough people. The early metal housing TV’s were a frequent culprit.

A lamp with a polarized plug won’t be damaged by reversed voltage, but more chance for a person changing the bulb with the lamp turned on.

It would be best if somebody knowing what they are doing fixed the problem. Who did the work? Your local building inspector might force them to fix it right at their expense. No sense risking it yourself if you can have it done by a licensed electrician at somebody else’s expense. If you just bought the house, talk to the lawyer that did the closing or your morgage holder. Oh, it you sell the house that way, the buyer can have it redone at your expense. May as well get it done now.