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Old 10-07-2008, 05:23 PM   #1
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Are old 2 prong sockets safe for modern electrical appliances?


I am moving into a new apartment, which happens to be an old townhome, and it has two-prong electrical outlets. In the past I have used items like these to simply convert it to a plug with a hole for a grounding pin. But I just read the back of a package of one of these and it says that if the outlet doesn't actually have a ground wire running then the adapter will not work. That doesn't make sense to me-- if a socket had a grounding path, wouldn't it already have the three-prong plug?

I am planning to bring some expensive electrical equipment into this home, but I want to make sure that I can hook it up safely, both for me and for the equipment itself. Can I use one of these adapters and/or a power strip safely? I have also read about GFCI outlets but that just confuses me more. According to this article, the GFCI outlet would be the way to go if there is no grounding path, but I don't have a way to verify either way (and it doesn't sound like it's even all that safe)

I am not willing to rewire, as this is just a rental property, but if the outlet can be safely and very cheaply replaced, then I am willing to do that. I am looking for a solution that is simply "good enough" for keeping me, my home, and my equipment safe.

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Old 10-07-2008, 06:05 PM   #2
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Are old 2 prong sockets safe for modern electrical appliances?


Those RadioShack (you can get 'em pretty much everywhere) things may work, so long as..

.. You attach the little tab to the screw in the center of the receptacle faceplate,

.. AND that screw is grounded. This may be the case if the wiring is BX (metal sheathed), AND the sheath is unbroken AND the sheath is connected physically to the panel AND the panel is grounded. (Old wiring, who knows?)

However, that may not be the most reliable ground regardless. It could even be bonded to neutral somewhere, somehow (not supposed to be, but old wiring..), and so even if you tested it, it may seem like it's grounded.

A GFI receptacle is the way to go -- it senses if current is going from the hot wire to somewhere other than the neutral wire (e.g. into you), and will shut off power if that's the case.

If you're using really expensive equipment, the GFI is better than the 2-to-3 prong adapter, but you should consider a voltage regulator w/spike/surge protection (from APC or some such) in front of your equipment. I've heard horror stories of severe undervolts from old wiring. Also I should point out that the GFI is not a "real" ground, it will just prevent shocking you; your equipment may require a ground anyway.

I know you're renting and said you're not looking to rewire, but you may want to discuss with your landlord having an electrician put in a dedicated, grounded receptacle for your equipment (if that's at all possible -- and at least it's not a complete rewire). It'll probably cost you less in the end than replacing whatever equip. it is you're plugging into the outlet.

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Old 10-07-2008, 07:30 PM   #3
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Are old 2 prong sockets safe for modern electrical appliances?


In the past I have used items like these to simply convert it to a plug with a hole for a grounding pin. But I just read the back of a package of one of these and it says that if the outlet doesn't actually have a ground wire running then the adapter will not work. That doesn't make sense to me-- if a socket had a grounding path, wouldn't it already have the three-prong plug?

If it has no ground, then the adapter does not cause it to become grounded, all it does is allow a grounded plug to fit in the outlet.

Sometimes in older installations there is a grounding wire that is run into the outlet and it is bonded to a metal box. If that is the case, then it is possible to effectively use a grounding adapter with a screw to bonded it to ground. However, if the box is already grounded, it is much better to just replace the outlet and the problem is solved. They cost well less than a dollar.

I am planning to bring some expensive electrical equipment into this home, but I want to make sure that I can hook it up safely, both for me and for the equipment itself. Can I use one of these adapters and/or a power strip

.What kind of equipment are we talking about?


safely? I have also read about GFCI outlets but that just confuses me more. According to this article, the GFCI outlet would be the way to go if there is no grounding path, but I don't have a way to verify either way (and it doesn't sound like it's even all that safe)
. One of the main points of a GCCI outlet is to verify the ground is intact. If you have a ground wire, go ahead and install a new outlet that is grounded. If not, then a GFCI out it's self does not solve anything.

Safe? Again - what are we talking about here, and safe for who, you or the equipment. Is a computer pluged into a ungrounded outlet safe for you? yes, unless your using it in the bath. Is it as safe for the appliance - maybe not.
Is a kitchen appliance that needs a ground installed un-grounded unsafe - the answer is much more likely to be yes.

I am not willing to rewire, as this is just a rental property, but if the outlet can be safely and very cheaply replaced, then I am willing to do that. I am

.It can if there is already a ground to the box. Otherwise a new wire needs to be run.

looking for a solution that is simply "good enough" for keeping me, my home, and my equipment safe.

.Safe is relative to the risk and value of the item being protected, if you provide more information about what kind of equipment your connecting, people here can tell you if what your doing complies with basic safely and electrical codes or not. But it is up to you to decide how much protection your equipment needs. Having a ground is not fool proof.

For what I consider valuable equipment I would not think twice about spending the money to ground an outlet, along with adding additional protection. (even hiring someone to install a ground wire would likely be less than $200). For you, maybe it's not even worth that much.

Jamie
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Old 10-07-2008, 08:23 PM   #4
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Are old 2 prong sockets safe for modern electrical appliances?


Quote:
One of the main points of a GCCI outlet is to verify the ground is intact.
My understanding is that the above is not true. 406.3(D)(3)(b) & (c) of the NEC allow the use of GFCI receptacles to replace non-grounded receptacles. There may be GFCI receptacles that also verify ground (not sure), but it is not their purpose. BTW, I forgot that in this case, the outlet has to be labeled with "No Equipment Ground" so that future users don't make the mistake of thinking that there is a ground.

Quote:
Sometimes in older installations there is a grounding wire that is run into the outlet and it is bonded to a metal box. If that is the case, then it is possible to effectively use a grounding adapter with a screw to bonded it to ground. However, if the box is already grounded, it is much better to just replace the outlet and the problem is solved. They cost well less than a dollar
Good point, that would be optimal. (Err, ...replace the outlet and connect the ground wire in the box to the green grounding screw on the receptacle, also connecting it to the box).
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Old 10-07-2008, 08:37 PM   #5
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Are old 2 prong sockets safe for modern electrical appliances?


i had one outlet here when i moved in that was 2 prong, no ground in box either. the inspector told me to leave it two prong or install GFCI outlet with just the b&w wires. he said "the GFCI will work the same either way. it's what they're for." just my $0.02 worth.

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Old 10-07-2008, 09:53 PM   #6
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Are old 2 prong sockets safe for modern electrical appliances?


[quote=ScottR;169481]My understanding is that the above is not true. 406.3(D)(3)(b) & (c) of the NEC allow the use of GFCI receptacles to replace non-grounded receptacles. There may be GFCI receptacles that also verify ground (not sure), but it is not their purpose. BTW, I forgot that in this case, the outlet has to be labeled with "No Equipment Ground" so that future users don't make the mistake of thinking that there is a ground.

Scott: I apologize, I was wrong. You are correct. Some surge protectors and surge protector outlets can verify grounding is in place and functional.

I've always only installed GFCI on grounded circuits, and kind of thought that is how everyone wired them, but I see that there is no requirement that there be a ground wire.

I've spent more time around commercial & industrial wiring and some stuff is different there. Everything is bonded / grounded - it all in emt conduit. I am kind of used to it all just being grounded. I'd use emt for everything if it were up to me. :-)

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Old 10-07-2008, 10:01 PM   #7
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Are old 2 prong sockets safe for modern electrical appliances?


The GFCI is code legal for replacing a receptacle with no equipment ground. However, some electronic device use the ground as an electrical reference. So, while it will be shock safe, it still may or may not be friendly to some computerized equipment. And, as far as BX being suitable for grounding, this is not allowed unless the cable has the bonding strip inside. Lots and lots and lots of the non-bonded stuff was installed well after the requirement for bonding.
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Old 10-07-2008, 10:05 PM   #8
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Are old 2 prong sockets safe for modern electrical appliances?


InPhase -- Whoops, bad call on my part as far as using the BX sheath for a ground.

Jamie -- Didn't mean to sound all high-and-mighty there.. I just happened to have read that somewhere and looked up the code. I could as easily have been wrong (e.g. above ).

Edit: And agreed, I'm not an electrician anyway, and have never (thank god) had to deal with ungrounded wiring, so it wouldn't have come up. You should hop on the EMT vs. NM debate thread, btw..

Last edited by ScottR; 10-07-2008 at 10:09 PM. Reason: Inline..
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Old 10-07-2008, 11:43 PM   #9
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Are old 2 prong sockets safe for modern electrical appliances?


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InPhase -- Whoops, bad call on my part as far as using the BX sheath for a ground.

Jamie -- Didn't mean to sound all high-and-mighty there.. I just happened to have read that somewhere and looked up the code. I could as easily have been wrong (e.g. above ).

That cool. Thanks for the information. I should have read more about it before I spoke. I falsely think of everything being grounded (just because commercially it is), even thought I know residentially most older homes have many ungrounded outlets.

I am rather old school / commercially minded in much of my construction knowledge. EMT, solid coper pipes, solid black iron, etc. (I know people love the pex, and csst, but I just can't bring myself to think they are ok). I still feel like I am doing some kind of hack job using NM.

I am not even 30, and I embrace most technology, however some things (pex, csst) just don't seem like an improvement to me.

:-)

Jamie
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Old 10-08-2008, 12:10 AM   #10
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Are old 2 prong sockets safe for modern electrical appliances?


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I still feel like I am doing some kind of hack job using NM.


Jamie
It took alot of electricians quite some time to come around to NM when it was introduced. Some I'm sure may never have. I don't really like it myself, but it's cheap compared to other methods, and it's legal. And customers like cheap and legal It really is no different than stringing THHN from one point to another, except that it's packaged as a bundle. And other than the superior thermal properties of the new insulations, the older NM cables are far tougher mechanically than the new stuff. I recently had to tie into some 12-2 that was installed in the 80s. I had forgotten just how thick that plastic was. Cutting into it is almost like UF.
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Old 10-08-2008, 12:12 AM   #11
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Are old 2 prong sockets safe for modern electrical appliances?


I hear ya. Professionally I do commercial network and phone installs (amongst other things), mostly in office buildings. I do plumbing/electric as a hobby, so I always pay a lot of attention to those things when digging around in drop ceilings and walls (and even better when the place is in the rough-in stage). So I have a lot of respect for EMT, copper, and black pipe.

That being said we differ insofar as I love PEX and, tho theoretically I like EMT better, in resi I've used NM exclusively. I mean, it's easy and millions of non-burned-down houses can't be wrong.. (Not trying to revive that EMT/NM debate here!)

B/c I come from a networking background, I'll do the "backbone" runs in my house in EMT and copper, and the branch runs in PEX and NM (maybe AC?). And everything gets homerun, which is just so much easier in PEX. (EMT also gets installed in any place that's hard to get to -- kitchen comes to mind, because cabinets and backsplash are way harder to patch than drywall..)

We're way off topic here I guess..

BTW, I'm almost 30 too (28), and I'm in contract for my first house.. Closing around 11/28. I'm improbably excited about the 2,000 DIY projects in my future, hence my ranting. And the new house is all NM from 2002. No ungrounded outlets in my future, at least..
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Old 10-08-2008, 12:29 AM   #12
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Are old 2 prong sockets safe for modern electrical appliances?


Last message crossed with InPhase's..

PVC pipe for DWV got the same rap when it came out as a replacement for cast iron, but you'll almost never see a house plumbed in 100% cast (unless local code requires).. like you said, cheap and legal [and it works]!

But I'm thinking maybe I'll knob & tube my new house..

(I'm absolutely j/k here, not flaming. Conversely to what I said, a lot of plumbers adopted polybutylene for water supply and probably had these same arguments.. then millions of homes needed their entire supply-side plumbing replaced).
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Old 10-08-2008, 12:59 AM   #13
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Are old 2 prong sockets safe for modern electrical appliances?


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It took alot of electricians quite some time to come around to NM when it was introduced. Some I'm sure may never have. I don't really like it myself, but it's cheap compared to other methods, and it's legal. And customers like cheap and legal It really is no different than stringing THHN from one point to another, except that it's packaged as a bundle. And other than the superior thermal properties of the new insulations, the older NM cables are far tougher mechanically than the new stuff. I recently had to tie into some 12-2 that was installed in the 80s. I had forgotten just how thick that plastic was. Cutting into it is almost like UF.
I ripped open my porch wall tonight and exposed the NM that was installed in the wall in 1963, It looked like 12 gage NM just due to the thicker insulation. That has changed a lot, the 12 gage now reminds me of lamp cord.

I think we accidentally took over the thread with off topic conversations.

We have given the OP a bunch of information,
Hopefully we can hear back from him.

Jamie
p.s. I forgot to add to the list of EMT benefits: you can't accidentally "un-ground" your outlet / device and last but not least, protection; I nailed some emt last month with a circular saw, didn't hurt a thing, had that had been NM....

Last edited by jamiedolan; 10-08-2008 at 01:05 AM.
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Old 10-08-2008, 01:27 AM   #14
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Are old 2 prong sockets safe for modern electrical appliances?


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Jamie
p.s. I forgot to add to the list of EMT benefits: you can't accidentally "un-ground" your outlet / device and last but not least, protection; I nailed some emt last month with a circular saw, didn't hurt a thing, had that had been NM....
I tell you what, you may not accidentally un-ground an outlet, but you most definitely can accidentally un-ground the whole circuit. I have seen countless EMT fittings where the set screws weren't tightened. And I don't mean loose or improperly tightened, I mean never had a screw driver near it. I was at China-Mart, er, I mean Wal-Mart not long ago and saw a receptacle on a column, but what caught my eye was the connector set screw. It looked long, so I turned it with a dime. Sure enough, never tightened. And yes, I was just shopping, and yes, I critique electrical stuff everywhere I go. Even when you run a ground in the pipe, studies have shown that the pipe still carries the majority of the fault current. EMT is great, I love the stuff and would rather work with it than with any other method, but grounding can easily be compromised if not careful.
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Old 10-08-2008, 01:47 AM   #15
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Are old 2 prong sockets safe for modern electrical appliances?


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I tell you what, you may not accidentally un-ground an outlet, but you most definitely can accidentally un-ground the whole circuit. I have seen countless EMT fittings where the set screws weren't tightened. And I don't mean loose or improperly tightened, I mean never had a screw driver near it. I was at China-Mart, er, I mean Wal-Mart not long ago and saw a receptacle on a column, but what caught my eye was the connector set screw. It looked long, so I turned it with a dime. Sure enough, never tightened. And yes, I was just shopping, and yes, I critique careful.
The stuff I see people do is kind of shocking. Was working on a house we were bought to flip, the guy that owned it was too cheap to buy wire nuts, and just taped all the wires together instead of using wire nuts.

In my house I have all metal boxes, and a mix of grounded and 2 prong outlets. I just did some testing and every box I tested is fully grounded. Now I am going to have to make sure the screws are all in well on my emt, they did quality elec work in general on my house, but it never hurts to double check.

Jamie

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