# [SOLVED] Earth, load voltages, test pens, sparks and reboots.



## Djizasse (Mar 14, 2010)

Hi all  I've found this forum while searching for USB sparks ground, etc..
Maye someone can enlighten me.

My home office has a lot of electronics plugged in. I've got 2 UPS, 3 PCs, 2 TFTs (one is 32"), AV Receiver, Amplifier and a few other gizmos.
Recently I've started getting shocks on the USB shields and when plugging VGA cables, they would spark against the PC's cases.
I used a test pen and it lighted up on the PC cases, RJ45 cables, USB shields, VGA shields, audio cables, etc.. This is expected as everything is connected.
I've sourced the problem to a faulty power extension cable. I've replaced it and now I don't get chocked and the test pen does not light up. The problem is that I started to get computer restarts, that did not happened before I correctly earthed everything. So, something is amiss.

I've also noticed that two of my appliances (equalizer and 32" LCD), when not earthed, give me shocks and the test pen lights up. I know that they should be earthed, but are they supposed to let this kind of voltage present in their chassis (and of course connected cables)? Could this be the source of my restart problems?

So, what should I do? Should I measure the electrical potential difference (voltage) between those appliances chassis and earth? Or will this ruin them?


----------



## SABL (Jul 4, 2008)

*Re: Earth, load voltages, test pens, sparks and reboots.*

What country are you in?? If you are in the US I would look for reversed polarity. Many appliances have the ground bonded to the neutral and reversing the polarity will energize the case, or housing of the unit. *Dangerous!!*


----------



## Djizasse (Mar 14, 2010)

*Re: Earth, load voltages, test pens, sparks and reboots.*

Hi, I've updated my profile. I'm in Portugal.
I never heard about that. So, maybe reversing the plugs of the "live chassis" appliances I may eliminate the problem? I'll try it.


----------



## SABL (Jul 4, 2008)

*Re: Earth, load voltages, test pens, sparks and reboots.*

220V is supplied with a single wire?? In the US it takes two wires to achieve that voltage. The problem may lie in the outlet or the cord (IF the cord does not have factory ends!!) I have seen mis-wiring in outlets and "home-made" cords... our system uses coded screws for connections. Silver is neutral and brass is for the supply..that applies to both the outlet device and the cord ends. If the connections are wrong you will energize the appliance housing and create a dangerous situation. Please consult reference material for your locale in regard to electrical connections and codes.


----------



## Djizasse (Mar 14, 2010)

*Re: Earth, load voltages, test pens, sparks and reboots.*

I had no idea of how the American system worked. Over here we've got 2 (neutral + live) and 3 (n + l + earth) prong plugs. But there's no such thing as polarity. We connect a plug either way. I thought that in the states it was the same. I've bought stuff from ebay and the american plugs were like this:









Shouldn't all electrical equipment deal with reverse polarity? The "transformer part" should sort things out. I remember that a few years ago I had one or two appliances that needed to be plugged the right way. But not anymore. But it's best to check it anyway.

But back to my problem, with all the searching for the shocking subject, one of my SATA cables became a little loose. Now it's all working. I'll connect the peripherals one at a time to check for problems.

I'll get back to report on this.

Thanks for your help


----------



## Djizasse (Mar 14, 2010)

*Re: Earth, load voltages, test pens, sparks and reboots.*

I've checked wikitravel and I see what you mean. 









The two vertical pins are different sizes, never noticed that with my ebay stuff. I just slapped them into a 220-110V transformer and I was good to go. I guess I'm lucky that all that stuff always sorted polarity


----------



## SABL (Jul 4, 2008)

*Re: Earth, load voltages, test pens, sparks and reboots.*

It seems that the US is the only country to use the 110/220 system from the different configurations of the plugs you have posted. If you notice, the neutral side of the plug has the larger prong for the US device.... that maintains correct polarity *if* the outlet has been wired correctly *and* the circuit panel wiring is also correct. From what you describe, polarity is not taken into consideration with both prongs being the same size... you will need to plug your devices in in the correct way. If only one wire is hot (energized) in your system you will have a problem with polarity. Some devices have the neutral wire connected to the case or chassis and reverse polarity will give you a shock...that is why our plugs have the larger prong on one side. 

Reverse polarity is a big issue in the US and we have test devices to quickly detect the problem .... if the defect is present the building does not pass inspection until corrected.


----------



## Djizasse (Mar 14, 2010)

*Re: Earth, load voltages, test pens, sparks and reboots.*

I've checked my LCD and it does not matter which way I plug the cable. If there's no ground, the chassis will be energized. I've checked the cable for continuity between ground, neutral and everything is OK (no continuity).

I'm going to contact the shop to see if this is normal (I don't think it is).


----------



## Djizasse (Mar 14, 2010)

*Re: Earth, load voltages, test pens, sparks and reboots.*

The shop gave me the contact of a certified Samsung technician. According to him, it is perfectly normal that the TV and other appliances have 110V running on the chassis.
I've checked the voltage between earth and the TV metallic chassis (and connections shields) and it measures 109V, so this checks out.
He also said to try and rotate the plug 180º (for reversing polarity), but this does not work. He says this too, is normal.

I know almost nothing about electricity and manufacturing codes, but this seems weird. I know that I'm supposed to have everything grounded, but even so, why the heck should I have voltage running to the ground? I always thought of ground as a fail-safe mechanism to prevent accidents, as a quickest route for "rogue electrons".

Well, at least I learned something new.

All that is left is to restore the connections to my other "misbehaved" electrical thing.


GROUND GROUND GROUND!


----------



## SABL (Jul 4, 2008)

*Re: Earth, load voltages, test pens, sparks and reboots.*

If any ground connection is missing, the cord (or the end) MUST be replaced and a ground established if it is a 3 prong connector. Never remove the 3rd prong if there is one present. Never use an adapter to bypass the ground. 

Good Luck


----------



## Djizasse (Mar 14, 2010)

*Re: Earth, load voltages, test pens, sparks and reboots.*

That is sound advice 
Thanks SABL 

Everything is correctly wired and working as expected.


----------



## SABL (Jul 4, 2008)

Thanks for returning and marking this thread as solved. With electricity, it is better to be cautious and safe. I have seen many quirks in dealing with electric when power was diverted due to a defect within the circuit. 

Please enjoy the other areas of TSF.... we have some highly talented pros in IT. I know where to go to get answers....:grin:


----------



## Djizasse (Mar 14, 2010)

So far, everything is working. I've already restored 500GB of data that were backed up. It ran without a single hick up. Prime95 stress test also ran fine. I hope that I can finally work without more shocking problems.

I'll stick around as this seems to be an excellent forum to learn stuff and resolve problems. And maybe I can provide assistance of my own.


----------



## Done_Fishin (Oct 10, 2006)

Hi, I'm late to the party due to unexpected visit abroad. I am so glad that you brought up this subject and you have solved it. Earthing is a major problem and its good that you have highlighted yours here for others to see and learn from you. I also wasn't aware of the US code of practice for electrical outlets so you have also helped me to learn something new, even though I don't work with US electrical equipment.

thanks to SABL for his help in spotting and highlighting a potentially lethal situation, and saving some people some grief.

:wave:


----------



## SABL (Jul 4, 2008)

Hey D_F!!

Visiting abroad, huh?? What's her name?? :lol:

Our electric system is different and we use 110/220 depending on the appliance. 220V is reserved for heating/cooling, water heater, cooking..(oven/rangetop) and other high "draw" applications.... the amperage is cut in half by using 220V. We use two hot "legs" (completely different feeds) to obtain 220V... the characteristics of AC will provide 220V *without* any neutral or ground. The appliance may require 40 amps (example) but each "leg" will draw 20 amps... two breakers (or fuses) are required to make the circuit. In this case the neutral acts as a safety and the ground (earth) is redundant... but should still be in place if provisions are provided. 

I am merely a carpenter but my survival is dependent on knowledge of my machinery and the source of power that is required to make them function.


----------



## Done_Fishin (Oct 10, 2006)

I understand the principle .. you use two phases of 110 Vac which, since the load is the same in each phase, means you require no neutral return. The same applies over here where we use (normally) a single phase of a 3 phase system but we must have a neutral return because the loads on each phase ( frequently used in different households) is NOT equal. When a house uses all 3 phases then a neutral is still required to balance out the unequal loading and provide a route back to the source. 

If, as I have experienced, the neutral return gets disrupted ... we get a massive surge across the phases causing overvoltage and equipment failure. Usually with lots of bangs ..


----------



## SABL (Jul 4, 2008)

Oh yeah, even with your system the loss of the neutral *will* will cause the circuit to try to complete itself... in your case you get 480V, we get 220V. We do have the third wire but only two are connected to most homes... 3 phase is for commercial applications and is not often found in a residential situation. It is still the same... lose the neutral and you get a voltage surge that will damage your electronics. Been there and seen it in action.... my son lost the neutral at the meter base many years ago and lost the furnace controls along with his TV. The electrician forgot to tighten the lug in the meter base for the neutral connection. A missing neutral can be just as dangerous as a missing ground (earth) and maybe worse.


----------

