plugs

[Goose Egg]

I've carved out the posts that are not related to the discussion about plugs, and DVDs.

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[sandman]

Further to Maoman's post, I have a DVD player that is not made in Taiwan (Philips) and while it plays DVDs, VCDs, and CDs, it does not accept illegal burns and I don't think it accepts discs from other areas unless they are specifically marked as acceptable anywhere. Check the small print on the disc -- it'll have a series of logos printed on it. For Taiwan, one of these logos must be marked with either a figure "3" or the word "all."

[sandman]

OK, here's a grounding question from a moron.
I'm a guitarist and singer and I'm sick and tired of getting 110v through the lip from the mike. How can I ground the equipment I use, given that there's no ground wire running from the wall socket?
This is a serious question.
Also, my shower heater has a ground wire running out of it, which is connected to the metal water pipe (not by me). Does this mean it is grounded?

[Goose Egg]

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[RPierce]

I am an electrical engineer (well, kind of) and I will say that earth ground plugs are not necessary but they do have functions.

The earth ground is tied to the chassis often so that EMF is absorbed. A floating earth means there will be voltage pulled onto the chassis. You might experience noise, you might experience small shocks. These shocks will not kill you, as at the most they will be half of the max voltage which ends up being 55v but usually less then this. This can kill equipment though. At my job we lost US$100k worth of equipment from this. Not cool. Also the noise, I don't know how much you will experience noise since the voltage won't be high enough to really radiate anything. But if the equipment fluctuates current draw or whatever at a good RF, a little voltage might be all you need.

Also, I for some reason don't understand transformers too well, so I don't know what effect no ground will have on those if they were meant to have one.

[dl7und]

<blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>Originally posted by Ryan P.:
<strong>I am an electrical engineer (well, kind of) and I will say that earth ground plugs are not necessary but they do have functions.
...
The earth ground is tied to the chassis often so that EMF is absorbed. A floating earth means there will be voltage pulled onto the chassis. You might experience noise, you might experience small shocks. These shocks will not kill you, as at the most they will be half of the max voltage which ends up being 55v but usually less then this.
</strong><hr></blockquote>
Sorry, but I have to object. If an electrical device (seldom enough in Taiwan) is equipped with a ground wire/cable/socket, then this is not without reason. While it may seem an "unnecessary feature" because in a normal household here you find almost no place to ground the device, it can very well save your life.
Actually there is not necessarily voltage on the enclosure if you don't connect it to ground. (By design, there must not be any voltage!) But grounding must be provided in case of malfunction. No, you will not get toasted at 110V - the resistance of the human body is too high. But you will probably have noticed that those shocks hurt a bit more in summer, when you're sweating. Then your skin resistance is much lower. Also at that time, you will not get toasted. But probably everyone of us has heard of a device called a "pace maker": If your heart does not operate properly, it will be stimulated by the pace maker. How? With electric impulses. Alternating current provides such pulses - 50 times a second. This is the speed your heart will try to reach when stimulated by an ungrounded metallic enclosure. What do you think how long will your heart run at 50 beats - each second...

<strong> <blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>
This can kill equipment though. At my job we lost US$100k worth of equipment from this. Not cool. </strong><hr></blockquote>
And not very professional...

<strong> <blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>
Also the noise, I don't know how much you will experience noise since the voltage won't be high enough to really radiate anything. But if the equipment fluctuates current draw or whatever at a good RF, a little voltage might be all you need.
</strong><hr></blockquote>
RF grounding and electrical grounding are two different things. You can have a very nice RF grounding and still receive electrical shocks - and vice versa.

<strong> <blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>
Also, I for some reason don't understand transformers too well, so I don't know what effect no ground will have on those if they were meant to have one.</strong><hr></blockquote>
You are an electrical engineer? Kind of? Where I come from, the basics of a transformer were taught in physics, 9th or 10th form and again in more detail at high school...

[4abudabit]

(Same user as Ryan P.)

I skipped out on the transformer days in college. I think its worth mentioning that all work I have done has been in semiconductors, which is where the 'kind of' comes from.

I would never worry about 110v, even when sweaty. Those EMS work out machines can often get up that high. Plus there's no way you will get a full wave of voltage. Most earth grounds are centertaps, right? Well, there are some that aren't. Like in the case of what killed my equipment.

Aren't there designs where the chassis as well as some circuitry is tied to earth ground? I've known many people getting zapped by EMF shielding in earth groundless houses. Including by a Fender amp, a pretty professional company. Are these designs not UL compliant?

And we didn't wire our lab, we aren't allowed to build them ourselves. What happened was the tweeker union guys didn't even hook up half the f$ck!ng earth grounds. And didn't check them either. We opened up all the benches and they didn't even try to wire them. So we had one BNC cable going from a function generator (which I assume was hooked to a working ground) to the expensive equipment which was hooked to a bad one. Now that I think about it though this situation doesn't apply to Taiwan because these grounds were in two's so one equipments center tapped ground was getting pulled by anothers ground which probably wasn't center tapped. Its like the two were connected but not connected to earth ground.


<blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote

RF grounding and electrical grounding are two different things. You can have a very nice RF grounding and still receive electrical shocks - and vice versa.

You're taking me a bit out of context, what I am saying is if the earth grounded shielding is around RF sensitive circuitry and the floating ground allows voltage fluctuations on the shielding you will get noise.

[Malkie]

Some comments... I used to work as an electrical engineer at one time:

* Only remove the earth pin from appliances if you know what you are doing (or understand the risks). Some technical knowledge is required to know when and why it is okay. If you want to know, study electrical engineering!

* Most Taiwanese houses do have at least one earthed 3 pin socket in the kitchen. The AC's ground can be used to earth other appliances, but don't connect them to the power (ACs are usually 240v, others are 110v). Watch out though, as you might expect if you have lived here for a while, the earth is often ommitted by the builders.

* If you are concerned about this and cannot find a ground, use an 'earth leakage circuit breaker'. It is a box that plugs into the power socket and provides an artifical ground. It measures the current out on one wire is the same as current returning on the other. If leakage is detected it will turn off the power. Very safe and not expensive. Electronics labs use them since good grounding cannot be ensured when you have open equipment.

* You can buy 3 to 2 pin adaptors - but use them correctly. They all have a third tab, this is meant to be used to connect (using a wire) to a grounded object. This is usually a water pipe or ground elsewhere. Use it! They are commonly used to connect computers to regular Taiwanese 2 pin plugs without the ground. This is INSANE - computers have metal boxes that could become live if faulty.

* For the guy in the band... the correct answer is to connect the ground on your equipment to a known good ground (water pipes, ground on other equipment etc). If this is not available, take a large metal stake (copper is best), put it into real ground outside. If the soil is not moist, water liberaly with salt water around about. Connect the ground wire to the stake. (I am not kidding, this is actually the recommended practice for temporary outdoor rigging).

[sandman]

Many thanks Malkie, you answered both the questions I asked in a way I found easy to understand. Also, thanks for the copper stake tip -- I have seen such stakes used outdoors, but didn't know what they were for.

Sounds like the kind of thing you'd tell a boy scout on his first camp -- "go outside and water the copper stake. Don't forget to use salt water, and bring me a left-handed axe when you come in."

[dl7und]

<blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>Originally posted by 4abudabit:
<strong>I would never worry about 110v, even when sweaty. Those EMS work out machines can often get up that high. Plus there's no way you will get a full wave of voltage.</strong><hr></blockquote>
This is still the same very dangerous statement. Your heart does not need 110v to be stimulated and collapse...

<strong> <blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>
And we didn't wire our lab, we aren't allowed to build them ourselves. What happened was the tweeker union guys didn't even hook up half the f$ck!ng earth grounds. And didn't check them either.</strong><hr></blockquote>
And it seems your company didn't check either. An electronics company that prefers to send equipment
worth US$100k (Really that much? How many spectrum analysers were that?) to Valhalla instead of implementing proper grounding (which includes to check for proper grounding prior to operation) still does not sound very professional. Where I'm working now (and this company is really not "top notch", even in Taiwan) the building is not really new and of the usual rather "cheap" kind common in Taiwan, so the wiring was somehow desolate when we moved in, but we used exactly the method Malkie described (copper stakes, available at some Wu Jin Hang, but not at each) to get us a nice earth grounding.
What I wouldn't trust in Taiwan (and is forbidden to do so even in Germany) is the water pipe, as these are mostly made of plastics within buildings. You may see a metal pipe somewhere, but this could switch over to plastics somewhere within the wall - and while you feel save, you gained nothing.

<strong> <blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>
So we had one BNC cable going from a function generator (which I assume was hooked to a working ground) to the expensive equipment which was </strong><hr></blockquote>
It probably was not, because the coax cable's shield should have served as ground connection to the other device.

<strong> <blockquote><font size="1" face="Verdana, Arial, Helvetica, Geneva">quote:</font><hr>
You're taking me a bit out of context, what I am saying is if the earth grounded shielding is around RF sensitive circuitry and the floating ground allows voltage fluctuations on the shielding you will get noise.</strong><hr></blockquote>
If it is "earth" grounded there is no "floating" ground. But I think what you are talking of are ground loops or improper ground return paths, which are again a different matter and lead to ripple in supply or signal voltages resulting in "noise" (though far away from RF).

But to return to the ground pin problem, this is something I never got used to in Taiwan - to abandon the ground in electrical installations, probably only to save a few NT$. Yes, you will not necessarily die if you touch a socket or anything being metal on your computer, but on a bad day with a few circumstances coming together you may very well happen to meet Odin. Its like with the safety belts in a car: Do you really need them? You can protect yourself, even when fully breaking. Until one day you happen to collide with a somehow "solid" object.
The grounding is one of the safety belts in electrical appliances - and in Taiwan probably the only one available at all. But its useless if you don't fasten it...