Grounding, our lack there of?

ssssly · 5692

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Offline ssssly

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on: April 21, 2010, 10:20:46 PM
Long story short I live in Japan and in Japan there is no ground on wall sockets, just the wonderful 2 prongers.

So couple of questions.

Is there any practical way to ground my system (a wire running out the window and staked into the front yard, while I appreciated the creativity, I did not find "practical")? And no, the wires do not exist inside the walls I checked.

If there is no practical way to ground the system are there changes to construction I should be looking at from a safety or sonics standpoint?

Systems (FPII, Quickie, Paramours, soon to be SEX, Eros, and an SR45 variant)

Thanks




Offline Doc B.

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Reply #1 on: April 22, 2010, 06:59:15 AM
One old school approach is to connect the equipment grounds to a metal plumbing pipe. In this age of plastic pipe that may not be useful. The more appropriate method is to drive a 6" copper rod into the ground and attach to that. Whether that meets with Japanese electrical codes or not, I have absolutely no idea.

Dan "Doc B." Schmalle
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Bottlehead Corp.


Offline Keim

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Reply #2 on: April 22, 2010, 06:29:10 PM
Doc gave the best response.  Doesn't have to be a pipe.  Could also be HVAC ductwork. 

Or get a cheater plug, and attach the wire to the screw holding on the plugs faceplate.  Not the best solution, but works.

Proud owner of modified Foreplay II, extended Paramour IIs, bi-wired Super Whamodyne speakers and a Seduction pre-amp.

Life is better at 33 and a third.


Offline JC

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Reply #3 on: April 22, 2010, 07:06:57 PM
I believe Grainger was referring to the required length of the copper grounding rod.  IIRC, 6 feet of length is the minimum, not six inches.

As far as I know, HVAC ductwork is not required to be grounded, and back-boxes for electrical devices such as outlets may or may not be grounded.  I would not want to hazard a guess as to the specific code requirements in Japan, mind you, but I know that in many instances in newer construction in the US, non-metallic boxes are acceptable, as is non-metallic conduit.

IOW, it always pays to check before deciding if something is grounded.

Jim C.


Offline Paul Joppa

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Reply #4 on: April 22, 2010, 08:36:00 PM
For the purposes of noise control, what you want is for all the audio system components to have a common safety ground. A power strip plugged into your step-up transformer will do that job.

I am not an electrical safety engineer, so I won't even try to advise, beyond saying that the grounded chassis is a widespread safety precaution. It does more than protect you from a normal mild shock; the main point is that if the chassis shorts to a really hot voltage, it will blow the fuse instead of you.

A quick google says that Japanese large appliances often come with a separate ground wire, leading me to suspect that many houses have a place to connect that wire to. Unfortunately I also learned that many ex-pats have had little luck finding knowledgeable help locally.

Paul Joppa


Offline ssssly

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Reply #5 on: April 22, 2010, 11:46:04 PM
The appliances are indeed grounded but they are on a completely different 240v circuit. In my house that circuit is on the first floor and runs directly from the transformer outside my house to the appliance only circuit breaker outside my house near the kitchen. My listening room is on the third floor on the opposite side of the house.

The outlets are all plastic minus the screws.

There is no ducting in the house and there is no plumbing on the third floor, it is a finished attic.

I do have the ground wire running from the amps to the step up tranny, but the tranny is not grounded.

I've never shocked myself, knock on wood. But everything seems more microphonic than in my old house where it was properly grounded.
 



Offline Doc B.

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Reply #6 on: April 23, 2010, 06:29:34 AM
Yes, guys, I meant 6'. Having driven a few of those into the clay in So.Cal. with a 10lb sledge when I was a carny (for our three 5500W generators), I am fully aware of how long those ba****ds are! Grounding won't help microphony. That is an acoustical/mechanical issue, not an electrical one. Increased microphony is likely due to your attic floor being more resonant than the floor in your old location, or your equipment sitting in a position in the room that is coupling more with your speakers than it did in the old room.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline syncro

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Reply #7 on: April 30, 2010, 05:53:54 PM
I've been wondering the same thing.  Similar to the situation in Japan, I live in a "2-wire" house, circa 1950.  My ST-70 amp still has only a 2-wire power cord.  So from what P.J. stated to address sonics, before I start tracking down hum, I should replace that with a 3-wire power cord and simply create a common ground between it and the Foreplay III preamp and my input source equipment.  Do I understand correctly that even if this would remain ungrounded it is doing the job of eliminating noise?

I do not take it to mean that anyone endorses the system not being properly grounded.

I have, in another vintage residence, installed a junction box especially to provide grounded, or "3-wire," power for an appliance by connecting a wire from the receptacle's ground terminal (and the metal junction box) to metal plumbing piping.  All metal boxes and conduit should be grounded.   For safety, the electronics work bench is the more important place for a grounded outlet.  And, per Bottlehead instructions for my Foreplay, a ground fault circuit interuptor (GFCI) type it should be.

David Bogle
LinnLP12>Hagerman Piccolo>Hagerman Ripper / Musical Fidelity V-90 DAC / Sansui TU-717>BottleheadFPIII>Yamaha M-45>Klipsch ForteII


Offline JC

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Reply #8 on: May 01, 2010, 12:37:39 PM
The "third-wire" ground is specifically for safety, where ever an appliance has exposed metal that could potentially be made "hot" by an internal fault.  In other words, anything with a power cord running into it, and metal on the outside.  The ground wire is electrically the same as the neutral wire from the AC line, but provides a redundant pathway that is there to insure that the metal remains at ground potential.  If there is a fault internal to the appliance, the ground path connected to the exposed metal is designed to blow a fuse or breaker.

That's the sole purpose of the third wire.  Current code allows for the elimination of the third wire ground on a device where insulation standards are such that the possibility of any exposed metal parts becoming electrically hot meets a certain threshold of improbability.

The third wire ground was added after enough faults happened and enough people got shocked that the code was changed.  This happened often enough with electronic equipment, since it was often desirable to have the metal chassis double as the signal ground and to have signal ground referenced to the AC line.  Since the equipment often operated just fine no matter what side of the AC line its signal ground was referenced to, it was only a matter of time before a two-prong plug was reversed and a chassis became "hot".  The first attempt at preventing this was the "polarized" two-prong AC plug, where the wider of the prongs was always to be the neutral side of the line and signal ground was always referenced to that side of the line.  Unfortunately, this system relied on outlets that would accept the polarized plug, and that were wired correctly by whomever installed them.  It also relied on consumers never altering the plug to fit into an older outlet.

Needless to say, people still managed to find a way to get shocked!  Hence, the authorities decided to make the system a bit more fool-proof by adding a whole separate safety ground.  Of course, consumers have still defeated this whenever they found it inconvenient!

Where this impacts audio equipment has to do with the various paths the safety ground may take on its way to the common grounding point back at the service entrance.  Two different grounded outlets may take  paths back to this point that vary widely in where they run and how long they are.  This means that the two safety grounds may be at a very slightly different potential relative to one another.  So, if two pieces of gear with their safety and signal grounds tied together internally are plugged into these two different outlets, their two signal grounds can end up having that same small difference in potential.  If they are also connected together by an unbalanced signal patch cable, then this difference in potential, small thought it may be, is indistinguishable from an audio signal at line frequency.

An easy way to avoid this in a home setting is to, as suggested, have all your audio gear plugged into the same power strip.  Only one ground path that way.

The important thing to keep in mind is the different purposes that safety-ground and signal ground are there for.  That they are often connected is confusing, but they really are two different things.


Jim C.


Offline Grainger49

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Reply #9 on: May 01, 2010, 03:34:55 PM
   .  .  .   I live in a "2-wire" house, circa 1950.  My ST-70 amp still has only a 2-wire power cord.  So from what P.J. stated to address sonics, before I start tracking down hum, I should replace that with a 3-wire power cord and simply create a common ground between it and the Foreplay III preamp and my input source equipment.  Do I understand correctly that even if this would remain ungrounded it is doing the job of eliminating noise?

It occurs to me that because your house is not grounded that you may not get the FP III and ST-70 hum that Paul and I had.  Adding a three prong plug might require you to jump around the input ground 10 ohm resistors. 

Your system chassis are grounded to each other through the interconnects.  That is, the outer conductor is tied to the chassis.  So the chassis of each component is wired to each other in the shield of your interconnect.

You may not want to put the three pronged power cord on your ST-70.  Or if you do have a pair of jumpers ready if you get hum.



Offline VoltSecond

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Reply #10 on: May 01, 2010, 05:20:48 PM
Safety ground and neutral need to be common at the utility box. Have a pro install a dedicated outlet. It has its own benefits.  A pro can run it in the wall or outside in conduit.

Either way, use a pro (or at least get a permit and schedule an inspection.) I got zapped at my mom's 2 wire home because some helpful person put in a three wire socket with safety connected to neutral at the socket next to the kitchen sink. At the utility box the neutral was "loose" and my hand help complete the path for the 115V.

A side note: A buddy and I solved some noise problems here in AZ simply by putting a drip line near his ground rod and tightening all the wires in his utility box. Again, some breaker panel connections were loose.  I've also talked with some one who put in 3 seperated ground rods at his utility box.

Note: I have the old version of the GE THQLsurge installed in my circuit breaker box. At the time I put it in, it had the lowest clamping voltage of the surge protectors out there. It's energy rating is on the low side, but I preferred the better clamp voltage.

http://www.homedepot.com/Electrical-Breakers-Distribution-Load-Centers/h_d1/N-5yc1vZ1xg1Zbm0k/R-100149175/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053



Offline Grainger49

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Reply #11 on: May 02, 2010, 01:34:50 AM
V-S, great advice.

One of the smartest engineers I have ever worked with told me to wet the ground rod monthly and salt it once a year.  That last one is in case the electrolytes are low.