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Grounding Active Pickups

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My own apartment, which I've moaned about in the past, has 3-pronged outlets by appearance only. Inside the box there are only 2 conductors. There are going to be venues like that. There are going to be electricians who have done their job wrong, and there is going to be plenty of vintage equipment being used out there. I mean, the very passage you highlighted stipulates 3 requirements to create the "impossible" scenario: 1. modern equipment 2. 3-pronged equipment 3. proper grounded outlet. I'd add a fourth: 4. properly-wired amp, but 3 is enough. And I will STILL agree (and always have... I thought it would go without saying...) that I'm unlikely to come across that scenario myself, especially as old buildings get replaced and updated with new stuff. But that's not really a point I was either making or disagreeing with. In other words, a straw man.

When I rewired my own guitars, I never bothered with that particular mod (following the source of that quote-- GuitarNuts' instructions), even though I had the opportunity... it just didn't seem worthwhile given that I'm not a gigging guitarist and that I have an outlet-checker. But there's a big difference between saying something is very rare and saying that it's impossible.

Ironically, I would have used that same quoted paragraph (which is from an article and instructions about why it can be a good idea to include preventative measures), and without the red highlights, would have used it to as an example of how it's possible to get shocked. If I felt like getting in someone's grille that was bugging me (for whatever reason) and chose to use highlighting, I might instead highlight the "LETHAL" part, the "WHEN THEY OCCUR" part, or the description of the shock path.

In other words.. I'm not sure why you bothered quoting that at me and selecting a passage to highlight.. it doesn't disprove anything I claimed, and is completely irrelevant to the conversation I thought was already over. I feel cornered into responding to this continued conversation, yet if I do I come off as a pedantic twat (which IS a shoe that sometimes fits. :D ) compared to you longhaired rebels. :D If you don't mind... enough already....

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Hmmm...

I typed that as a joke(kinda nerdy). If your amp is giving you a shock through the guitar Greg. I would be happy to try to figure that out with you(probably easier through PM's, and only if you want). My comment to you in my post was related to reversing the phase and neutral conductors(at least that is what I took a reversed power outlet as). Honestly I would have to look over a schematic to figure out what might be happening with the switch. A little testing with a meter could tell you how much potential is present when you flip the switch(probably a good idea, cause vintage or not it is not supposed to zap ya).

Peace,

Rich

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Heh, yeah, I didn't mind that at all-- it's all good info to have, esp. since I'm no expert. I was more referring to Maiden's "point" highlighted in red.

The Garnet definitely zaps when you flick the switch. It always has! I'm quite certain that it only has a 2-prong cord, for one thing. I'd have to have a look. Not sure how to test with a meter and all that jazz, and I'm not sure where a schematic could be found. The Garnet company is neato, though.

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Greg, if your apartment is like that, 2 wires only, if something was to happen to you, those are grounds for a law suit. In USA and it's territories electricians has to follow codes when wiring houses. Every house I help wire was tested by us, and then they were QA by the eng. Is this your own place? Do you rent? And when was it built???

My grandma house was 2 prong, built in the early 30's. It was a pain to rewire it. Since it was a concrete house we had to break all the walls to expose the 1/2" tubing and replace it with 3/4-1" to be able to run the new wire.

while we were doing this, I ran a ground wire from the box to my room, because I got shocked by ,my little Peavy Audition 20

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Greg, if your apartment is like that, 2 wires only, if something was to happen to you, those are grounds for a law suit. In USA and it's territories electricians has to follow codes when wiring houses. Every house I help wire was tested by us, and then they were QA by the eng. Is this your own place? Do you rent? And when was it built???

My grandma house was 2 prong, built in the early 30's. It was a pain to rewire it. Since it was a concrete house we had to break all the walls to expose the 1/2" tubing and replace it with 3/4-1" to be able to run the new wire.

while we were doing this, I ran a ground wire from the box to my room, because I got shocked by ,my little Peavy Audition 20

Actually, it would depend on when it was wired and what codes were in effect at that time. Most juristictions do not require bringing existing systems up to current code standards unless you modify(modify does not include repair or maintenance on existing systems).

A good solution for safety in a system that does not have a reliable equipment grounding system is to utalize GFI receptacles or breakers. The ground fault interupters monitor the flow of current between the phase and neutral(grounded conductor/white). If it senses current imbalance (meaning it is taking a different path, outside of the circuit) it will trip the circuit open. The GFI's that are designed to protect people from getting electricuted are designed to trip before the threshold of damage to the human body. The only down side to GFI's is that loads such as a motor can cause tripping because of the inrush current. Jacuzzi tubs are an example of a need for GFI protection, but an issue with inrush currents because of the pump motors. There are GFI devices that are designed to have a higher tolerance to current imbalance (allowing the motor to start), and still offer a reasonable degree of protection. GFI protection is now required by code for new installations in; Kitchens, Bathrooms, Basements, Outside Circuits, Crawl spaces (hope I remembered all of them).

Greg,

If you want to check things out with your meter, simply check for a potential (voltage) between parts that you are touching, and parts to a surface that you are sure is connected to the grounding system. If there is voltage present you can get shocked, if not you can't. I would do one round of testing with the switch in one position, then change the position on the switch and compair your findings.

Peace,Rich

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I'm not sure I'm able to identify a "definite ground" on that thing. :D

Maiden and Rich: here's the longish version:

My apartment building has been around since the dawn of time. Or at least, since the 50's. It has concrete construction, and therefore I can't even run my own grounds to a spike (and I don't know if I'm permitted to install my own spike) or to a cold water pipe without much difficulty OR an unsightly mess. I noticed the problem immediately upon moving here (but not BEFORE signing the lease... grrr) because I checked the outlets prior to (or shortly after? I can't recall) plugging in my recording equipment and computer. Called the landlord to explain the situation, and he sent over an electrician who swapped out all the standard 3-prong outlets for 3-prong GFI units. This should theoretically go a long way to prevent shock hazards, but it doesn't help the noise levels of my recording equipment, which of course wants to be grounded. I basically can't record any audio right now because of how cruddy and noisy the equipment sounds. I'm not sure how much of that is ground, and how much of it is being situated near a telephone interchange (or whatever it's called... it's a telephone node right outside my window).

Needless to say, I didn't look into the recording equation before signing the lease. My and my fiancee just said, "Yeah, it's a cool apartment, and clean! Let's take it!".

The Garnet amp is currently at my folks' place, so I'd have to go out there to check it and to see if it's in fact 2-prong. I can't fit it in this ap't, and it'd be too loud anyhow. <grin>

I'll try to remember to check when I'm over there next.

Greg

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That sucks man, changing the plugs to the newer GFI units won't do nothing if there is no ground to route the current. You got the same problem we had... a lot of money and work involved to get it to what you need. Have the breaker box been upgraded? if you can get the tubing diagram you can at least rout ground to where your recording equipment is and at least have that room wired correctly

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It's worth looking into. I'll see what my landlord has to say on the issue. I have no clue about the breaker box.

Greg

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You guys crack me up

Caveat-THIS APPLIES TO U.S. WIRING

When it comes to the use of ground, grounding, grounded conductors, it becomes very confusing. The National Electric Code uses these three terms to define elements of wiring systems. They refer to the Neutral conductor(the common point of a grounded wye connected secondary or the corner common on a grounded delta secondary) as the "grounded conductor". This is because the common point is connected to the earth at the transformer(via ground rods, plate electrode, concrete encased electrode, ground ring, etc...). When the conductors from this transformer are brought to the service equipment you terminate the grounded conductor on a bus(the neutral buss). You then establish a "grounding electrode system" (with electrodes mentioned above) to develop a low impeadence path to the earth. This is a path that is used to disapate unwanted currents(lightning, accidental contact with a different power line, etc..) not developed by the source(the transformer servicing the building). All the significant metal(water piping, building steel, sprinkler pipe, gas pipes, etc..) in the builing is then "bonded" to the "grounding" buss. At this point and this point only you bond the "grounded"(neutral) buss and the "grounding"(earthed electrodes and bonded metal systems) together. All wiring after this point the Grounded conductor(neutral, white or gray wire) and the "grounding" conductor(green, green w/yellow stripe) remain isolated from each other in an effort to avoid parallel paths to the main bonded point. The "grounding" conductor(green one) is also called the "equipment grounding" conductor, because it is what is used to bond any exposed metal parts that may come in contact with a phase conductor. The main purpose of the "equipment grounding" conductor is to facilitate the overcurrent device(fuse or circuit breaker), by providing a low impeadence path for current to flow and thus device opens the shorted circuit.

In the case of an amplifier. You bond the metal housing to the "grounding"(green) conductor through the wall outlets third usually rounded and slightly longer terminal. The two remaining terminals are you phase(hot), and your "grounded"(neutral/white/gray), the neutral terminal being slightly larger than the phase terminal. The phase and neutral will usually feed a transformer in the amplifier, at that point there is no electrical connection between the primary and secondary of the transformer, unless the secondary is bonded to the housing. If it is bonded to the housing then you have a an electrical connection via the buildings grounding and grounded system conductors, this would electrically connect the secondary windings only. When you do this you create a "seperately Derived system", or a system in which the "grounded"(white/neutral) conductor is seperately derived from the main system "grounded" conductor . Ok stopping now.....

Greg,

QUOTE

You don't ground anything "to" the bridge, even in a passive setup. The bridge gets grounded along with other components to the "ground" lug of the output jack. The problem being that you CAN get a shock if your amp has its polarity (?) switch reversed, or if you plug it into a reversed power outlet. You should always check outlets before using them anyhow.

So, the EMG instructions basically say that you do not NEED this extra "shielding" (your body being added to the shielding material!) with EMG actives, so you should simply not connect the bridge to ground, thereby removing any shock hazards related to having a grounded bridge. I suspect they also feel you're less likely to screw things up and introduce a ground loop into your circuit.

Reversing the hot and "grounded"(neutral/white) will not give you a shock, as they will be connected to the primary side of the amps transformer and will not be electrically connected. In the U.S. they have been trying to standardise the connection to outlets with a cord configuration that keeps things straight between the neutral and phase conductor. For many years there was no difference in the size of the terminals, and the circuit will function. Probably the most significant difference would be in keeping the equipments wiring predictable, but the "grounded neutral conductor is supposed to remain isolated from the "grounding" conductor throughout the building and in any equipment.

Peace,Rich

Now Wes, you can call me a Nerd

Nerd :D

You can't just flip it around as me being "without humour" now,

I can and I am.I did not read the rest of that post,because sadly my attention span is not what it used to be.I imagine your petulance in this area stems from everyone around you in your life falling asleep as soon as you open your mouth to utter one of these long-winded rebuttals...I know MY eyes glaze over.And you are probably headed for an anuerism.(sp?)(get it?"headed"?...aneurism????..anyone...)

peace out dood,your harshin' my gig :D

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Dude, you bumped a 2-month old thread to say that. :D

STFU already.... jeez....

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Awesome that you're amused by pretending someone else is unhappy. :D Knock yourself out! :D

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