2 vs 3 prong charger - advantages vs disadvantages?

With a three prong charger you are connected to the ground of the electrical system. You are protected from electrical hazards. They have a ground wire that safely carries away electricity if the neutral wire in an outlet fails. So safety here is the key.

As sig mentioned, the 3-prong AC plug has a ground. Without the ground, you may notice a slight tingling sensation as you use your computer. The sensation is not a safety issue, but it can be annoying.

Buildings wired to have the 3 prongs have 3-wire cable in the wall, with the "bare copper" wire being a common ground for the entire structure, keeing your used outlet safe from power surges from across the room. The cost of rewiring an entire building from 2 to 3 wire usually involves cutting every sheetrock panel and is most decidely not cheap. Besides, under building codes, if the owner finds *any* other issue during the require (structural, insulation, etc) they *MUST* fix it -- if they do not open the walls they can leave it even if they scecretly know about it.

In addition to what I mentioned above a possible problem with using the adapter without the ground plug is that the two prong plug is not polarized. It doesn't have one lug larger than the other so it is interchageble in the outlet. If the charger's transformer is designed not to care then no problem. If not then the neutral and hot legs can be switched causing an issue with the charger. It's usually not an issue except for aplliances that are internally switched.

steve359 wrote:

The cost of rewiring an entire building from 2 to 3 wire usually involves cutting every sheetrock panel...

Not necessarily.

The old wires can be used to pull the new wires through the conduit, or if there is none new wires "fished" from holes drilled in the attic or basement through the top or bottom plate using a long thin wire with a loop at the end. The old wires are cut and left in place and not removed obviously.

They can place new outlets right through decorative finishes like kitchen tile even.

Electricians try to do minimal damage to drywall (thus painting, trim, wall paper, wainscoting etc.) as little as possible as customers scream bloody murder.

However if they have to cut the drywall, like to get past a firebreak in the bay, they do it with minimalism and in a fashion that it can be easily patched, so they would cut the drywall on the firebreak only, then chisel out a notch in the wood for their wire and that's it.

And they do have some very long drill bits, so it's possible to drill through sideways through wall studs, thus leaving a tiny hole to patch only.

And another option is being able to run wires outside or inside, placing a cover over the wires to protect them, this is usually done for solid wall construction like concrete buildings. Run the wires outside the building and drill holes straight through to the outlets without messing up any drywall at all. 😉

sig wrote:

They have a ground wire that safely carries away electricity if the neutral wire in an outlet fails.

Dangerous voltages never reach the Mac laptops from the power brick, why they went with 2 prong plugs for so long.

Because the Mac laptop is metal, it can carry a charge if a higher voltage bare wire falls on it,, but with it grounded it will short out immediatly upon contact, thus not present a lingering threat to someone as long as it's plugged intto a grounded outlet.

steve359 wrote:

Still $$.

Minor compared to the cost of rewiring a house.

And may need a new fuse panel to accommodate a new standard of wiring.

If it's the old fuses instead of the breakers yes, also it usually coincides with uping the amerage to 200 watt service.

A typical 3 bedroom house should be about $5000-$10,000 or so to rewire depending.

Patch a few holes in the drywall and match the paint?, minor, a few hundred dollars.

Explains some leave "what passed inspection" as-is.

There are certainly situations where one goes to do one thing and the building dept will require more to bring certain things up to code. However it's for the safety of the house and those in it, lowers the insurance bill too.

In some areas, if it's a historic house, then the Historical Society gets involved and makes one do a lot more drastic changes to revert or maintain "historical aspects and details" which combined with building codes upgrades can turn a small roof leak on a 24" on center rafter roof into a major construction project to turn it into a 16" on center rafter roof, with new sheeting and "historical style" roofing that only one company makes and charges a fortune for it.

I've seen new homeowners of historical houses either go bankrupt over it or just keep replacing a tarp over the leak area, incurring daily fines and paying the city when they sell the house at a discount.

Soon as the building department finds out about the leaky roof, like from a too goody contractor the customer was calling to get estimates, then the city knows and calls the customers homeowners insurance, which if the house is under bank loan, the bank will be upset if the insurance is pulled as that is required to maintain the loan.

It's a real nasty mess one can get into with buildings and of course there are always sharks ready to bounce and they have their fingers all in the city too.

Not entirely accurate.

Still $$. And may need a new fuse panel to accommodate a new standard of wiring.

Explains some leave "what passed inspection" as-is. Learned that from Mike Holmes.