How to easily upgrade 2-prong electrical outlets to 3-prong outlets without grounding them

Check your electrical codes – some frown upon placing low voltage DC alongside mains wiring. This can also introduce noise with badly shielded cables.

So, what, put a wall wart somewhere else? The voltage drop will be pretty sizeable if you want to pass enough current to charge, say, a single iPad unless you use really thick wiring.

Just stick with a high quality multi-port USB charger from a reputable seller like Anker which can easily charge several iPads and phones and takes up a small amount of space.


And even if you’ve tested your plumbing, and it is, in fact, like totally grounded, a few years from now, when you have a plumber over to fix a leak, or remodel the kitchen, or the well-water people to update your water softener, that “grounded” plumbing might cease being grounded.

It’s best to just let the electrical system do electricity stuff, and let plumbing do plumbing stuff. Don’t try to make plumbing do electrical stuff.

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You mean to tell me that even though I replaced all my receptacles with red ones it doesn’t mean I’ll keep getting electricity when there’s an outage?

Infuriating, for sure. I remember when my place was being inspected the inspector noted the redundant GFCIs throughout and we made the builder fix this so it was one GFCI per circuit.

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Most low voltage consumers (like USB) are looking for a regulated 5VDC. That’s very expensive to provide over even modest distances.

Wire resistance becomes significant when you’re dealing with long runs at low voltage. If you provided 5 volts at the breaker panel and run 40 feet of 24 AWG to an outlet (not an unreasonable distance for a typical run), you’ll have only 3 volts coming out.

Even a six foot (2m) run will drop the voltage to 4.7V, which is so low that it will affect device reliability. 4.75V is the absolute minimum for USB; 4.9V+ is better.

If you upgraded the low voltage wire to 14 AWG, 40 feet would be the max run length before the 5 volts dropped to 4.75V. If you’ve ever routed wire, you know how fast you go through it. 40 feet would typically get you up a floor and maybe 15-20 feet after that.

The most you could realistically do would be to install combination outlets that have both electrical and USB jacks, and produce the low voltage near the consuming devices.


Only for the ayn-caps, and they tend to be morally bankrupt.

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The house I grew up in still had it in place…my dad had a modern wiring install done (well, 1950s so I guess mid century modern :slight_smile: the original wiring was done in the 1890s) . We kept some of the original fixtures . The newel posts had ornate lighted globes on them, really spectacular. the switches were interesting; hardwood turnings with brass leaves inside. All through my youth I would encounter vestiges of the tube and knob stuff; put a lot of the insulators to use in antennas


Seeing a lot of comments about “check your local electrical codes”. Do y’all live in a fantasy world where building coded are freely available to the public for consultation? Im so jealous!


Oh my gosh this 100%.

Spend high, get a known name, and a model that is reliable and has a long track record. Protection devices have a long, long history of success, and there’s established track records for good devices. It’s overdramatic of course to say “This can save a life and it might be yours”, but , yeah, might be.

Getting cheap GFCI’s is like buying a second hand airbag.


Most locations in the US are close enough to NFPA70 or are NFPA70 that you can use their free access to the codes to look things up.

Mind, it’s only the important stuff , but the free access definitely covers anything you’re going to be doing in a residential single family unit.

No Problem Snl GIF by Saturday Night Live

This is mostly a misunderstanding / confusion of two or three issues.

It has never been acceptable since grounded outlets became standard to have a grounded outlet where the ground pin is connected to a water pipe instead of having a ground wire running back to the electrical panel. This doesn’t mean people never did it, but has never been a legitimate configuration. The purpose of the ground wire in an electrical outlet is to provide a fault path for current in the event of a short circuit back to the panel in order to allow the fuse / breaker to blow. For this to work the path has to lead back to the electrical panel so it can form a circuit. Even if the pipe is also connected to the panel, you can’t really count on it being a solid enough connection to clear a fault, and if the only connection is through ground it is even more likely.

Separately, the ground network established at the primary electrical panel needs to be “earth referenced” by a connection to physical earth. This is not needed for the fault protection described above, but prevents development of a large potential between the electrical system and the local earth. This is usually done with dedicated ground rods, but in some situations can be provided by the cold water supply to the house. This is a case where it used to be more common to use the water pipe as the only ground reference for the panel, but now you generally need a dedicated ground rod as well.

Finally, it is required that any large metal structure that could potentially be energized in a fault condition be connected to the electrical ground. Some people see these connections and think that the copper pipes are being used as a ground path for the electrical system but actually it is more like the reverse.


Most of the houses that I worked on that still had knob and tube vestiges dated to the turn of the century as you mentioned. Most of the wall switches that I saw still in use had heavy oversized push buttons. I wish I had kept one of the best details I saw on the second floor of a center staircase late Victorian era home finished inside with beaded heart pine and black cypress trim. It was a wooden, recessed site-built circuit panel box with a swing out glass fronted cover, and with a very steampunk knife switch for cutting the 2 separate circuits it contained. It had 2 huge old fuses about 4 inches long and thick as a cigar set in copper lugs. It was still in use and you could still buy the fuses at the old local hardware store. It’s a miracle that the place never burned down.


You don’t really want to distribute low voltage DC (5 or 12 V) over long distances as described by others. The instances where we do low voltage distribution it is usually 24 VAC or 48 VAC, but there aren’t a lot of residential applications for that other than thermostats. Its better to run Ethernet – you can power small loads with PoE and also have data. If you want to future proof, install conduit, not random wires that you think might be useful in the future.


I’d do 48VDC, to allow using PoE devices. 1/4 the current of equiv. 12VDC, 1/9th of 5VDC.

But that might mean it’s out of the “low voltage” rulebook. Anyone know the rules, Canada-specific preferred.

I’m not an electrician, although it might appear I play one on the Internet.

ETA: or like @ejeffrey said!


Which would clearly make you smarter than me, who obviously forgot that the normal rules of voltage drop still apply down in the single digits where real world rules apparently apply. Who knew?

In the US it’s generally 70V, although there are state-specific carveouts to keep us amateurs from installing alarms and data centers.

GFCI breakers are expensive compared to the duplex GFCI outlets here in the US. Granted, the only reason we have the NEC in the first place is due to the industry wanting to unify their standards instead of the government telling them where to go and what to do when they get there… :slight_smile:

The UK and other places are more sensible about such things.

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Hooookay; (warning: ramble n rant)

What I’m about to type only applies in the US. I’m not a licensed electrician, but I’ve mucked around enough with being a handyman/general maintenance type person who knows their exact limitations as far as when to put the insulated screwdriver and chicken stick down and call a proper sparky to set my house on fire instead of trying to do it myself. YMMV.

Swapping two hole outlets with three holers: Only do this IF (and only if!) there’s an actual ground wire IN THE BOX. In the US, White is the neutral (return) line, black (or red, blue, or rare cases white with black stripes) will be the live wire. A bare copper line or green is the earth ground.

If there’s no ground, you might be able to get away with it IF the box is metallic and grounded. Buy an outlet tester, it’ll give you the rundown on if you need to have the place rewired. The nicer ones also have a button which will test the GFCI outlets as well, and the tool is worth having in the house tool kit.

Along that line: Houses built from the 60’s onward will usually have a ground line. HOWEVER: current code dictates that the earth ground be the same wire gauge as the power and neutral lines; houses from the 60’s and 70’s… don’t, unless the house got re-wired in the intervening decades. (my house was built in '61, and has a 14 or 16 gauge ground line with 12 gauge power and neutral. It was code back then, but it’s not now, and if I was doing major work on the house, I’d have to remediate it, which is… expensive.)

If there is no ground line and the box isn’t grounded in some manner, be resigned to calling in the pros to either re-wire the house or figure some other arrangement. Use a licensed and bonded electrician, they are generally worth the extra spend over the long haul.

Regarding running low voltage DC power lines for “future use”:
TL;DR: Don’t. Just don’t. The poor sod who comes after you will end up insulting your family for the seven previous generations before ripping it all out. For powering USB, swap the outlets for ones with built in chargers.

On a side note, you can (and probably should!) run low voltage data and signal lines around, with a few given limits. the Big one is this:
LOW VOLTAGE LINES MUST BE SEPARATED FROM POWER LINES. The reasons for this are for twofold: EM interference, and accidentally running high voltage down a line that wasn’t designed for it and setting equipment (and your house!) on fire. (I mean, we all like hearing a 60 Hertz buzz on our speakers, right?)

If you want to run low voltage lines around the house to ‘future proof’ the place? sure, if you are running Cat 6 cable for networking.

There are boxes designed for low voltage cabling (the keywords are “Structured cabling enclosures”) and will hold audio cabling, ethernet, coax, and fiber if you are insane or are running a 10GbE backbone between rooms. They also have an option to have an outlet attached to it to power things like cable modems, wired routers, switches, coax signal amps, etc.)

When I bought my house, one of the things I knew I could do was to swap the outlets around, because it’s a good general principle. Plus, the old outlets were loose, and the old ‘push wire in, pray it holds’ style from the 70’s or 80’s. I also trashed a couple sawzall blades and put in one of the aforementioned structured cabling enclosures, and ran ethernet and coax to it from various rooms. I did pay for an electrician to come out and do a few specific things with the house wiring, because they were all outside my wheelhouse of ability, and I wanted it done in a timely and professional manner. :slight_smile:

Final thoughts:

As noted upstream in these comments, buy a well known brand for in-wall outlets, be they GFCI, Power with USB chargers built in, or even low voltage jacks. These things will be used on a daily basis and need to last for years, possibly even decades. Some no-name or six character ‘brand’ from Amazon might save you a few bucks, but if it causes your house to burn down, that’s something you’d really not want, especially when the insurance company denies the claim because the company that sold it no longer exists and the device was never UL listed. And I care for you happy mutants, even if I don’t agree with all of you all the time. :slight_smile:

Personally, I’m partial to Leviton for power and datacomm products, but pick something well known from either the local hardware store (including the Orange or Blue Monsters) first before hitting up the Amazons.

And on that note, Have a good evening and take care.


That’s actually what our 5V solution used; 5V power supplies running on 48V DC, but in a different context (48V battery plant ). As for the rules in Canada (where I am) commercial AC is always run by itself; you can’t even run battery backed inverter sourced 120V AC or isolated AC in the same conduits. beyond that I don’t really know.

I remember seeing the brass plates with two interacting push buttons; push one in, the other pops out. The cabinetry on those early power-telegraph-telephone devices was often pretty sweet

Same thing happened in the 480V antenna drive panel of a radio telescope that I work on. You can see that the little guy’s paw was on one leg of the 480V and the other paw had just touched another 480V leg.

(Note from @ficuswhisperer: I blurred the image.)