/?\ Laptops don't have electrical grounding????

[ki4jgt]

I have a house (Renting) which has no grounding (Third prong in USA) All the outlets have holes for the third prong, but none of them are grounded. (I know this because the building inspector came and checked them out - then ordered the landlord to install outlets with only two prongs or to ground the house. <I got the two prong option>) I had a couple of plugs my landlord didn't change over (Which I am using to plug in my laptop) anyway, so I've been asking on (Yahoo Answers) Will my laptop get messed up if it's not grounded. Several of the responses were, laptops don't have grounding.
My question to you guys is, if laptops don't have grounding, why do they have a third prong?

[bukwirm]

The ground is there for safety purposes, it has no electrical function. Your laptop should work fine with no ground. Many laptop power supplies do not have a ground prong.

[ki4jgt]

The ground is there for safety purposes, it has no electrical function. Your laptop should work fine with no ground. Many laptop power supplies do not have a ground prong.

What kind of safety purposes are we talking ???

[Paqman]

What kind of safety purposes are we talking ???

In the case of a fault, it provides a path to Earth that isn't through you.

[uRock]

I am amazed the local code allows ungrounded receptacles. Very unsafe. I wonder if the owner's insurance company knows of this.

[1clue]

The round prong is called "chassis ground" in the USA.

It connects to the metal chassis (container) of a device, so that if the hot wire ever touches the chassis the fuse/breaker in the house will blow rather than causing the entire device to be "hot." It prevents the device from shocking somebody.

If you have a plastic case, the chassis ground is not required.

[piquat]

I am amazed the local code allows ungrounded receptacles. Very unsafe. I wonder if the owner's insurance company knows of this.

In some areas of the country it depends on the age of the home. My house doesn't have them... except for an addition that was built after the code change. If I were to rewire the house or make another addition, that would need grounded receptacles also. Really dependent on location IIRC.

[disabledaccount]

In fact, "grounding" is wrong word - in most cases this connection is not really connected to earth potential but to Neutral wire, often with use of differential current sensing device. This solution is provided to avoid danger situations if neutral wire is broken (and could be considered as some kind of redundancy). Additionaly separate wire will have lower voltage drops, because normally it doesn't carry load currents. In case of shorting between phase wire (hot) and metal case this ensures lower and safer "touch voltage".

[seenthelite]

Most Laptops use about 20 volts Direct Current and the Alternating Current power supplies are double insulated. Therefore grounding is not an issue. imo. :)

[lisati]

This thread raised my interest: My house has a ground wire from the internal electrics connected to a spike in the ground, which I nearly damaged today when dealing with a large Scottish thistle (http://en.wikipedia.org/wiki/Onopordum_acanthium) prior to mowing the lawn.

As has already been noted, the main purpose of the ground wire is to shunt away dangerous voltages in the unlikely event of a live wire touching the case, hopefully tripping the fuse/circuit breaker/RCD/safety gadget that cuts the power before someone gets zapped or worse.

(/me spares the troops an anecdote from when I was young, concerning a nail and piece of wire shoved into an electrical socket.)

[seenthelite]

This thread raised my interest: My house has a ground wire from the internal electrics connected to a spike in the ground, which I nearly damaged today when dealing with a large Scottish thistle (http://en.wikipedia.org/wiki/Onopordum_acanthium) prior to mowing the lawn.

As has already been noted, the main purpose of the ground wire is to shunt away dangerous voltages in the unlikely event of a live wire touching the case, hopefully tripping the fuse/circuit breaker/RCD/safety gadget that cuts the power before someone gets zapped or worse.

(/me spares the troops an anecdote from when I was young, concerning a nail and piece of wire shoved into an electrical socket.)
In New Zealand you have a multiple earthed neutral system for the distribution of the AC power, so by regulation you require the earth stakes at each point of supply. DC power for Laptops are above earth. So they are safe.

[disabledaccount]

Most Laptops use about 20 volts Direct Current and the Alternating Current power supplies are double insulated. Therefore grounding is not an issue. imo. :)Heh, I don'want to make things too complicated, but truth is that every power supply ensures that secondary DC ground will have reasonable potential with reference to Neutral wire. This is achieved by connecting secondary ground with primary (net) section by special compensating circuit. Almost none of PSU's have full DC separation and none PSU's can separate high frequency AC currents. Therefore f.e. many audio devices have additional grounding connectors that can be used to elliminate power network noises/spikes, etc and to equalize potential between cooperating devices
:)

[lisati]

In New Zealand you have a multiple earthed neutral system for the distribution of the AC power, so by regulation you require the earth stakes at each point of supply. DC power for Laptops are above earth. So they are safe.

<off topic triva>Our power outlets here are similar identical to yours across the ditch. When I was in Ashmore (near Surfers', north of Brisbane) back in '07 I was able to to use my laptop and camera gear without any extra adaptors. BTW, the news coverage of Brisbane looke like they're having a tough time of it at the moment.</off topic trivia>

[seenthelite]

Heh, I don'want to make things too complicated, but truth is that every power supply ensures that secondary DC ground will have reasonable potential with reference to Neutral wire. This is achieved by connecting secondary ground with primary (net) section by special compensating circuit. Almost none of PSU's have full DC separation and none PSU's can separate high frequency AC currents. Therefore f.e. many audio devices have additional grounding connectors that can be used to elliminate power network noises/spikes, etc and to equalize potential between cooperating devices
:)

http://www.users.zetnet.co.uk/computing/MainPage/SecDepts/Physics/Resources/Glossary/DoubleIns.html

http://en.wikipedia.org/wiki/Extra-low_voltage

[Yougo]

if you're worried about plugging any device in an 'ungrounded' socket, there are extention sockets that have their own fuse. should anything happen, power is cut from the extention.

[disabledaccount]

http://www.users.zetnet.co.uk/computing/MainPage/SecDepts/Physics/Resources/Glossary/DoubleIns.html

http://en.wikipedia.org/wiki/Extra-low_voltageIn case of laptops, TV sets, etc Double Separation is obtained by using plastic housings and it has nothing to do with PSU internals. You can destroy housing of some old laptop PSU and You will find at least one varistor and/or one capacitor connected between secondary and primary circuits.
This is protection against static electricity that can break transformer insulation and against transformer cross-capacitance, that otherwise would carry very high voltages (up to 400V high frequency AC voltage on 230VAC network) to secondary ground - due to the nature of DC-DC converters.
Secondary ground of every modern PSU is connected electrically to primary section - but impedance is so high, that it won't cause electric shock in normal conditions.

[seenthelite]

<off topic triva>Our power outlets here are similar identical to yours across the ditch. When I was in Ashmore (near Surfers', north of Brisbane) back in '07 I was able to to use my laptop and camera gear without any extra adaptors. BTW, the news coverage of Brisbane looke like they're having a tough time of it at the moment.</off topic trivia>

off topic, yes Australia and New Zealand use the same standards for wiring regulations. (AS/NZS 3000:2007) Floods, I went 40 k's up the road to see some friends, last week Thursday, and while I was there it started to rain and rain and I got home today. It is a terrible experience people are enduring with their homes going under and worse. We are fortunate our home is on high ground. So we are going down to Brisbane in the morning to help clean friends properties.

[ki4jgt]

This thread raised my interest: My house has a ground wire from the internal electrics connected to a spike in the ground, which I nearly damaged today when dealing with a large Scottish thistle (http://en.wikipedia.org/wiki/Onopordum_acanthium) prior to mowing the lawn.

As has already been noted, the main purpose of the ground wire is to shunt away dangerous voltages in the unlikely event of a live wire touching the case, hopefully tripping the fuse/circuit breaker/RCD/safety gadget that cuts the power before someone gets zapped or worse.

(/me spares the troops an anecdote from when I was young, concerning a nail and piece of wire shoved into an electrical socket.)

My cousin had a story like that once. He tried to charge a 9V battery by taking two wires and putting them into the + and - sockets and then touching it to the battery. Let's just say the results were a big bang and him laying across the room. :-)

[ki4jgt]

if you're worried about plugging any device in an 'ungrounded' socket, there are extention sockets that have their own fuse. should anything happen, power is cut from the extention.

What would they be called :-)

[cascade9]

<off topic triva>Our power outlets here are similar identical to yours across the ditch. When I was in Ashmore (near Surfers', north of Brisbane) back in '07 I was able to to use my laptop and camera gear without any extra adaptors. BTW, the news coverage of Brisbane looke like they're having a tough time of it at the moment.</off topic trivia>

Some of Brisbane is pretty much flooded out (another word starting with 'f' would be applicable as well, I'm sure you can imagine which one). Nobody should be that suprised as far as the old suburbs go. I'm not that suprised about what happened to some of the new estates, thats what you get when you build on a swamp.

Sorry about that, I just saw your post lisati and couldnt help myself ;)

[TheNessus]

What kind of safety purposes are we talking ???

The apartment below mine is ground-level. The whole building has no grounding. Anyway, they were two roomates. And I say were, because one of them died because he got himself electrocuted. This is how: they have a yard, and the one who died, his gf came with her dog. He played with her dog in the yard, and stepped on the outer unit of their air-conditionair. When he stepped on it, barefoot, and reached up to hold an object to maintain a firm grip, he closed an electric circuit. 250 volts shot through him for a whole minute, to cardiac arrest. Grounding would have prevented that and diverted the power to the ground instead of the close circuit he created.

[tgalati4]

But the dog survived.

[ki4jgt]

The apartment below mine is ground-level. The whole building has no grounding. Anyway, they were two roomates. And I say were, because one of them died because he got himself electrocuted. This is how: they have a yard, and the one who died, his gf came with her dog. He played with her dog in the yard, and stepped on the outer unit of their air-conditionair. When he stepped on it, barefoot, and reached up to hold an object to maintain a firm grip, he closed an electric circuit. 250 volts shot through him for a whole minute, to cardiac arrest. Grounding would have prevented that and diverted the power to the ground instead of the close circuit he created.

O, well at least it wasn't like the capacitors they used to make when they grounded light poles in peoples yards. People thought they were safe and then all of the sudden. Anyway, thanks for the tip.

[beniwtv]

Laptops / Computers internally run at ~12 Volts DC (+12V wires), so there is no chance of getting electrocuted on that.

However, their power supplies convert 90-250 V AC to 12/14 V DC, so those can potentially be dangerous, and therefore are required to have grounding, under all circumstances.

Operating a power supply without grounding is NOT recommended, while technically possible.

[uRock]

Let us not forget that with PCs, grounding is important for channeling static discharge away from the components.

[Paqman]

As has already been noted, the main purpose of the ground wire is to shunt away dangerous voltages in the unlikely event of a live wire touching the case, hopefully tripping the fuse/circuit breaker/RCD/safety gadget that cuts the power before someone gets zapped or worse.


Unfortunately the protection on your circuit won't stop you from getting a zap. It just isn't quick enough for that. What's it's there for is to prevent fires. In the case of a short to earth on your mains voltage, large current would flow, which would be a real fire danger if the MCB/fuse didn't step in and trip it out.

So you could still get a lethal shock, but at least it won't be made worse by burning your house down around you as you lie unconscious :)

[ki4jgt]

So how complicated is it to add grounding to an older house?

[seenthelite]

Double Post

[seenthelite]

While they are in normal use Laptops are not connected to the grounding or earthing conductors of the AC power outlet. However if you are servicing or changing components of a Laptop there is then the need to use earthing or grounding.

[Chronon]

Unfortunately the protection on your circuit won't stop you from getting a zap. It just isn't quick enough for that. What's it's there for is to prevent fires. In the case of a short to earth on your mains voltage, large current would flow, which would be a real fire danger if the MCB/RCD/fuse didn't step in and trip it out.

So you could still get a lethal shock, but at least it won't be made worse by burning your house down around you as you lie unconscious :)

You seem to be confusing circuit breakers with chassis grounding. Chassis grounding provides a path to ground so that a large current will flow out of the compromised device to ground and keep the voltage of the chassis close to ground. It is then the circuit breaker's job to break the circuit under the large current and prevent consequential high temperatures.

Chassis grounding prevents the charging up of an instrument chassis, which would then be apt to discharge through a person.

[Paqman]

So how complicated is it to add grounding to an older house?

Not complicated as such, just labour-intensive.

[uRock]

Rewiring a house to add the third line of copper to every receptacle takes a lot of work, not to mention copper isn't cheap. Especially if the building permit requires the sheetrock be stripped to run properly protected wiring, so nobody gets jolted when putting a nail in the wall to hang up a picture. Also the consistency of the earth around the house may not have the ability to absorb electricity. If that fails then longer, more expensive grounding rods have to be driven into the ground. Though I have heard stories of people soaking the ground with water the day before the inspector came in, so that the ground would score higher when tested.

[Paqman]

You seem to be confusing circuit breakers with chassis grounding. Chassis grounding provides a path to ground so that a large current will flow out of the compromised device to ground and keep the voltage of the chassis close to ground. It is then the circuit breaker's job to break the circuit under the large current and prevent consequential high temperatures.

Chassis grounding prevents the charging up of an instrument chassis, which would then be apt to discharge through a person.

I was responding to Lisati suggesting that MCBs were there to protect you from shocks, which they aren't.

[uRock]

I was responding to Lisati suggesting that MCBs were there to protect you from shocks, which they aren't.
Not completely true. I once had a guitar amp that started shocking me through the strings after the ground prong broke off. Luckily it was low voltage, but it put the electric in the electric guitar.

[seenthelite]

I was responding to Lisati suggesting that MCBs were there to protect you from shocks, which they aren't.
True, the average Circuit Breaker or MCB or Fuse in a home is rated at 20, 15 or 10 amps which can kill a person. RCD's (residual current devices) are what people should consider fitting to their homes,(as well as MCB's) these trip at 10 or 30 mA which is considered safe.

[uRock]

True, the average Circuit Breaker or MCB or Fuse in a home is rated at 20, 15 or 10 amps which can kill a person. RCD's (residual current devices) are what people should consider fitting to their homes,(as well as MCB's) these trip at 10 or 30 mA which is considered safe.
I have heard that those burn out really often, but they are required by code for bathroom outlets where I live.

[1clue]

Regarding house wiring.

I just went through a plumbing upgrade, which in my city requires a certain interface with the electrical system. I also regularly talk with a cousin who is an electrician.

The 'hot' line is where the high voltage is supposed to be.
The 'neutral' line is where the power normally returns to the power company.
The 'chassis ground' is hooked up to the chassis of a device, not normally used for completing a circuit.


All 3 of the above wires require a route back to the electrical fuse box. In my city, they have updated the codes so that if you mess with the electrical enough to require a building permit, they require a SEPARATE bare chassis ground going back to the breaker box for EVERY DEVICE. Not just going to the nearest place where there is chassis ground, but every outlet has its own wire going all the way back to the circuit box. WTF?

IMO you should investigate your local building codes anonymously through a call to the city before you consider getting an electrical building permit.

Now, regarding the spike going into the ground:

The electrical box is required to have a connection from the chassis to the plumbing through the most direct route.

As well it requires a connection from chassis ground to the spike outside.

Those two features are for lightning safety so they don't kill the whole neighborhood or burn your house down in case of a lightning strike.

If you have an outbuilding with a separate fuse/breaker box, then the second building also requires the plumbing and ground spike connections.

All that comes from my city inspector.

FWIW I don't think it would be that difficult for a professional electrician to update your house, but it definitely is a PITA to crawl around in the attic so I would say it's a prohibitive do-it-yourself project.