This is a North American existing household wiring (60hz 120/240) system question.

Before the HDTV arrives Monday...

My 1956 Ranch style home is wired almost exclusively with un-grounded receptacles and the LR has a single 20 amp circuit for lighting and receptacles. There is a single hard-wired lighting fixture and a few switched outlets. The LR is the location for the system.

The system will initially consist of a Monster HD 1080 surge suppressor (I got a great deal on it) feeding power to:

1. DMP BD-35
2. Panny 42" plasma 1080p 85u line
3. AVR system (Kenwood 9020 based system feeding 4+center -> Onkyo 606 7.1 system very soon)

It's likely that a PS3 will be added fairly soon and/or a router/switch for the LAN (want to relocate the WiFi to upper level of house).

Modest power demands; 20 amps is more than adequate for the room's past, present, and future demands.

But there's those darned non-grounding (2 prong) duplex outlets...

While I am perfectly capable of correctly re-wiring the entire house (permit and inspections, of course), it would be a monstrous undertaking to even snake in a new branch circuit. The house was custom designed and built, finished walk-out basement, etc. My 200 amp main panel has spaces (and equally important, I own spare 20 amp QO breakers for it); the issue is running the wiring. It cannot be done without seriously ripping into finished walls and ceilings, even if I simply run straight to the attic, over, and down through the wall top plate. That finished walk-out basement + custom design (even vacuum cleaners have their own nifty little closets)... for the sake of this discussion, it is not feasible to get a 12-2 with ground circuit in.

My thought is to do a proper 2-wire installation of a GFCI into one of the duplex receptacles on that wall (probably fed with a 12-3, but I digress...). Both available duplex receptacles have one outlet controlled by 3-way light switches, so I'm only going to feed the power center from an outlet and let it handle 100% of the device demands. 15 amp power center with 8 outlets; matches up OK.

Obviously I won't get a good light on the power center for leg-to-ground protection (because there is no ground wire; only hot and neutral) <shrug>.

So... any other practical solution folks can advise me on?

The majority of the homes in the U.S.A. were built and wired long before grounded branch circuits were required by the NFPA-70 NEC folks caving in to pressure from industry to sell more copper. I suspect most people (other than AVS readers, I hasten to add :p) in the real world just slip a cheater plug on the surge suppressor (or worse, replace the 2 prong outlet with a 3 prong outlet and either float the grounding prong or tie it to the neutral <shudder>). Since I know "better"... the electrically safe way to adapt a 2 wire ungrounded circuit to a grounded prong receptacle is with a proper 2 wire GFCI installation is my choice.

If I have a problem with the CATV feed, I guess I could slip an isolation transformer in someplace I have access (multiple points). I do have an unrelated coax question (separate post later).

Should I tie chassis grounds together on all the equipment?

I know there is a binding post on the power center and my Kenwood system for that purpose, but haven't really looked at the TV (not here yet), BD-35, or Onkyo 606 to see if there is an external provision for a reference ground wire. However, it occurs to me that every component with a grounded appliance cord on it will already have chassis grounds bound through the power controller via the grounding wires. And any 2 wire appliance cord fed stuff... doesn't have a ground anyway.

So - is my approach (GFCI) OK or is there some other approach I should take? I am NOT going to pull a new branch circuit for this, regardless, until the day I remodel and re-wire the entire house (2-6 years away).

It can't be that big of a deal... most of the world uses ungrounded outlets for this sort of thing (230v - 250v, more or less, at 50hz). But I'm all ears for knowledgeable advice.

TIA,

Tom

Not what you want to hear, but if it were my house. I'd find a way to get the necessary grounding before using the equipment. Dispite your dislike of feeding the money hungry copper suppliers...lol. Either that or stare at the weather network 24/7 for weather warnings.

my .02

Licensed Canadian electrician with approx. 15yrs experience.

Seriously - Thanks for the reply. Point of reference - I'm extremely "in the business" with all building systems (33 years) and have licensed electricians with 30+ years of experience on staff at work (among other disciplines and trades).

find a way to get the necessary grounding before using the equipment.

Re-read: The question I'm asking is "why?" - to the grounding of the appliance cords. Most household wiring in the world does not include grounded outlets, which are strictly an NEC-driven requirement. It is what it is; I'm not making an NEC tech comment, although I can make serious scientific arguments on either side of that question. Does most of the rest of the world without grounded convenience outlets (or N.A. residents who dimply plug 'er in) explode their equipment or suffer horrible A/V problems as a consequence? I think not - but I don't know (hence questions).

Dispite your dislike of feeding the money hungry copper suppliers...lol.

Nooo... that's not what I wrote. Although I suppose conspiracy theorists could point a finger at Anaconda somehow, the historical fact is that NFPA caved in to silly science from wire manufacturers. As a more recent example of that sort of NFPA behavior, look at the debacle of Arc-fault circuit interrupters - really bad scientific data from the patent holder (obvious to anyone who cared to look). Only now, years later, are they actually performing as claimed, and only very recently can one even obtain a tester for combination AFIs. NFPA subservience to industry is a well-established fact, unfortunately. (they still write pretty darned good standards despite that).

And really, when I write that I am not going to tear into finished walls and ceilings to run a new branch circuit, I mean it - not going to happen; it's just a darned TV going into the same space the existing TV and AVR stuff has been sitting for years. There is no way, and I mean no way, to make the run without doing so much work that I might as well tackle the whole house re-wire. And that will be driven by the upstairs kitchen (power hungry bugger) - I have plenty of power everywhere else, fed by a 200 amp main. I have the skills, knowledge, experience - looks at these things every day. This is a tough PITA.

So my questions still are as per original post.

... and it's nice to hear from a licensed electrician here! Thanks for the reply.

Tom

Most household wiring in the world does not include grounded outlets, which are strictly an NEC-driven requirement.

Make that North America.., we don't use the NEC. The ESA (electrical safety authority) up here in Canada make it a requirement as well. :)

I've never been outside of this continent other than spending some time in Cuba. So I can't comment on how the rest of the world handles the issue. I have done some retro work on machines for european use, and know that they do not have a ground reference in the system. Which makes the ground pointless.

The ground is for safety. Mainly, to force a circuit to open if line voltage goes anywhere other than where it's meant to go. In a system that floats, (such as the european 220 system) there is no reference to ground. Therefore faults to chasis don't/can't open the protective devices in the circuit.

So will you have any A/V issues if you don't have a properly grounded system...? I honestly don't know. Although I would be surprised if Monster honoured any warranty claim for damaged equipment if there suppressor was used in such a system. I'd look into that, if I were you.

to force a circuit to open if line voltage goes anywhere other than where it's meant to go. In a system that floats, (such as the european 220 system) there is no reference to ground. Therefore faults to chasis don't/can't open the protective devices in the circuit.

Yep. But the GFCI will trip in that case -much sooner (milliamps) than over-current protection (amps) - which is why that's an approved (and sensible) way to adapt. Am I making sense? I'm kinda loaded up on turkey and trimmings, so my brain is only working at 1/10 normal... :p

Edit: In a 3 wire system, a hot wire fault to chassis will flow current, possibly up in the 15a - 18a range or even (momentarily) much higher until the 20a over current protection trips at the panel - or 15a in the case of the Monster. In a GFCI protected 2 wire system, 1) a similar fault with no path to complete the circuit probably does nothing significant until 2) someone/thing provides a path to ground, thus tripping the GFCI at a very low current flow long before the over current protection trips. Hmmm. Assuming both oc protection and GFCI are working properly, I'd give the safety edge to the GFCI circuit.

I think the potential damage or lack there of to components is more difficult to generalize for a number of reasons, but the Monster is not designed to deal with chassis faults - it's to clamp incoming voltage spikes and filter out incoming noise. So it is NOT going to provide component protection on a downstream fault, other than oc protection at a slightly lower current than the circuit is already oc protected for (15a rated vs 20a at the panel). Damage, if any, will have occurred long before then. And a chassis fault is a DEFECT in the component - I think a clear liability path is intuitively obvious.

So this is clearly not a safety question - it's what I intended - how likely is it that I will have an A/V performance problem induced by the absence of a ground wire back to the panel? If so how do I mitigate it without running a new dedicated circuit? Ground loops, poor cable routing, etc are also not part of the question - those are other causes with other solutions. (Actually, the 2 wire system is probably unlikely to have a ground loop problem in the first place).

Dang it, you're making me think too hard on a full belly! I think I'm going to take a nap now...

Thanks - sometimes it's too easy to ask a question places like this instead of thinking - now I'm thinking (doesn't hurt too badly).

Anyone?

Yep. But the GFCI will trip in that case -much sooner (milliamps) than over-current protection (amps) - which is why that's an approved (and sensible) way to adapt. Am I making sense? I'm kinda loaded up on turkey and trimmings, so my brain is only working at 1/10 normal... :p

:( I'm a little ashamed to admit this but.... I'm a little confused as to how a "G"round "F"ault "C"ircuit "I"nterrupter will sense a ground fault when it has no reference to ground...?

Forgive me...I've never done a retro like you're suggesting.

Eh, poor naming convention - the "ground" the name refers to is perhaps meant to mean "wrong path to earth". GFCIs work by sensing tiny current differences. Believe me, a 2 wire GFCI really does work just peachy. If the threshold current difference between hot and neutral is exceeded, it trips open. Really, really tiny current - the idea is to keep folks from being electrocuted. From 1st hand experience, I can tell you you don't even feel a shock - they just trip.

I remember when GFCIs first came out. The first versions were a little annoying when used on site power due to perceived nuisance tripping. There are some loads (eg reffer compresor motor starts) that may cause nuisance tripping, which is why the codes allow a non-convenience outlet (like dedicated behind a reffer) to omit GFCI even though its location would otherwise dictate. In practice... nuisance tripping with quality NA made GFCIs is a thing of the past - if it trips, there is a problem someplace.

This is not the case with several inexpensive imported "brands", which are plagued with poor QC - high failure rates, comparatively speaking. I don't try to save $2 on a GFCI - ain't worth the risk.

Now I REALLY need to go take a ZZZZZZZZZZzzzzzzzzzzzzzzzzz......

oh...sorry. I didn't mean to imply that I didn't know how a GFCI worked. It looks for a difference in current between the hot/neutral pair. Here's the problem I can't wrap my head around...: If you have no reference to ground at all in your service, how does voltage leak away from the hot/neutral loop in the circuit.? The fault that would normally bleed off current, and therefore trip the GFCI, has no path to complete a circuit because it essentially "floating".

I have an application where all the outlets are ungrounded in a wing of my building. The wiring is so old there's only hot and neutral - 2 wires - no ground wire. When I plug in a UPS and use it, there's always a red "improper wiring" light lit on the back of the UPS. Even it senses that there's no ground wire present. What is the solution besides ripping out all the walls and re-wiring everything with 3-wires?

Yes, you are absolutely correct. Gotta have current flow; potential is machts nichts.

Who cares if there is no current flow? That's where "we" come in, touching things... on the LR carpet, I could grab a hot wire and no current is going to flow (maybe not really that perfect of a world, but close). But IF it does, the GFCI trips, so it is safe. An OC device like a circuit breaker never has a chance to trip because the current never gets within 2 magnitudes of order of its trip point.

In a 3 wire system - assuming the chassis is bonded to the third (ground) wire via the grounding plug - the fault shorts to earth, pulling the massive amount of current required to trip the breaker, flashing, letting the magic smoke out of something, emitting stink etc. IOW - something fries, but the house wiring does not heat up and burn the joint down. No touching is required - a fault fries stuff but not the house.

We never get to that point in a GFCI-protected receptacle.

And again - to my way of thinking - if there is a fault to chassis in a bit of gear, that is a serious, fundamental defect in the equipment. And no surge suppressor or filter is going to protect that equipment; they address problems with UPSTREAM (incoming) excessive voltage and/or noise (which is really impressed voltages anyway, just without enough duration - energy - to clamp the MOVs or whatever).

Hmmm. Let me think about the voltage clamping function of an ungrounded surge suppressor for a sec... nah, I can't tell for sure without a schematic of a particular device. What I AM sure of is that a properly designed one should work fine anyway, ground or no. And... we get hit 10-20 times a year hard enough to make green fireworks at the neighborhood transformer (feeds through wooded ravines) - two hammers within seconds as the power company control gear resets (radial feed to it). Never, ever have had so much as a twitch on any equipment in a heavily electronic-laden house; surge suppressors have done their jobs, sans grounds.

(Some of our non-NA members must think we're discussing angels dancing on pinheads)

Nah - I'm fine with going the GFCI route ILO new branch circuit. If I have any A/V performance issues, I'll post, but I really doubt that will be the case. Actually, I'll report back regardless.

Thanks again - the discussion with you has made me think this through better. It helped a lot since you know what you're talking about (which is really why I posed a question here in the first place, eh?)

I'm ready for pie now :D

Edit: Whoot! I just found a route to get a proper and legal grounding conductor to the outlet in question. Yaay! Moot point now. :)

I have an application where all the outlets are ungrounded in a wing of my building. The wiring is so old there's only hot and neutral - 2 wires - no ground wire. When I plug in a UPS and use it, there's always a red "improper wiring" light lit on the back of the UPS. Even it senses that there's no ground wire present. What is the solution besides ripping out all the walls and re-wiring everything with 3-wires?

For now, either don't use a cheater (stop whatever you're doing) or pop in a GFCI (read the instructions!) - a GFCI tester is CHEAP, so get one and use it. That way it is SAFE. The light is (probably) going to stay on for now. There is a way to eliminate that, but it is questionable because it may not be safe in several situations, and... forget I was even thinking about that :eek:

Then consult an electrical contractor. You may not need to rip out walls; it is going to depend on how he can route new wiring. Without being in your particular building, there is no way I (or anyone else) can know. If it is a commercial building it may be extremely trivial to run a new circuit(s). In a home, might be more work or might be almost as trivial - details matter.

It's probably not that big of a deal to run a new circuit. In my specific case, it is a really big deal <shrug> any good electrician will figure it out and give you the straight scoop.

HTH,

Tom

Did you think about a GFCI circuit breaker and a whole house surge suppressor?

Kevin - As a matter of fact, yes. But since I figured a path to get a ground wire to the outlet... a lot cheaper alternative for now. A whole house re-wire is in my plans for a couple of years from now - when I re-model the upstairs kitchen. That will be a total wiring job - underground feed, distribution panels, power, cat 6, phone lines, coax, etc. Means adding AFIs where required, which is fine. May GFCI protect required locations at the panel(s) or at the outlets (current configuration); not decided. I'll also decide then what, if any, whole house surge suppression I want. Would still want voltage monitoring and esp. noise filtering at the point of use for some applications.

This whole LR HDTV set up is a precursor to other projects - the A/V equipment going to the LR now will displace to the MBR in the next 6 months.

Thank you for the suggestion - it's the easiest way to get shunted surge suppression and a safe 3 wire outlet anywhere in the house.

Tom

I know you sound like you know what you are doing, but are you ABSOLUTELY 100% sure there is no ground?

I used to live in a 1954 townhouse that did not appear to be grounded. Except for the one outlet in the kitchen that the fridge plugged into was grounded to a metal box. I had a non-working outlet in the finished basement (REAL pine paneling, about 1/2 thick!) and called in a pro to try to fix it. I watched as he replaced it with a grounded outlet. It turned out that the ENTIRE house was run WITH a ground, but they were all cut short, except that one in the kitchen. He managed to grab hold with his pliers and pigtail on a new ground. After seeing that, everytime we moved furniture in a room, I did the same thing and eventually ended up with a fully grounded house.

I'm just saying check VERY CAREFULLY and it may not be as bad as you think.

If you go the GFCI route, make sure you attacth "NO GROUND" label.

Good luck!

Not that it has anything to do with this situation, but I just discovered that you probably can't use a GFCI circuit breaker in an old "Knob and Tube" wired house. Because the often did not run the hot and neutral together and would share the neutral between different circuits.