# Does a light need a ground?



## Erebus (Jul 28, 2009)

I have a few of the lights shown below and I am going to build a box around them and put some theater gels infront of them to give off some color. I have a ton of those small 6' extension cords and was wondering if I could just cut off the end of the plug and use that for these lights but they don't have a ground. I know the lights will work with out a ground, I just don't know how safe it is. I know the cord needs to be able to hand the watts so I am already considering that.


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## jaege (Aug 23, 2009)

The ground (the typically green or bare third wire) is included for the purpose of safty. Nominally, it is supposed to be attached to all metal components in the curcuit and then via various connections) back to the grounding strip in the panel box. Should the hot wire accidently come into contact with a metal part, it would short and trip a breaker, rather than remain live and zap the first sucker to touch it. I am sure that you have noticed that not all extension cords or electric appliances have such a grounding prong. So its not completely nessacary for proper operation. So long as you are certain not to strain the wires, and make sure that no bare wire is exposed ANYWHERE in the curcuit it should be okay. Of course I can say that because electricity is my friend. It may not be yours.


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## MotelSixx (Sep 27, 2008)

Why not rewire it a grounded extension cord? And Jaege is right, make sure the wire can handle the light.


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## Decrepit Desecr8shun (Aug 10, 2009)

Perfectly correct...but the word ground(often used by electricians) is an incorrect term for the whole thing....according to the lingo,"ground" is electrically the same as "neutral" in home & commercial. In reality,there is no such thing as either!
An A/C...by definition alternating current changes it's polarity ie: one leg becomes positive and the other negative on the next wave section it changes legs and the one that was positive is now negative and vice versa_hence the word alternating. Typically A/C is between 100-127volts...the highest (and the lowest)my meters registered during testing anyway...over 7 different states. Now,on 2 the real danger...there is very little danger from U.S. 120v A/C....you will only recieve a burn (2nd degree @ worst). *UNLESS* the electricity crosses across your heart or brain...Then you are in trouble,and here is why. Electricity in the United States is different from that in Europe or elsewhere in the world. I know what ur thinking...electricity is electricity right? *WRONG!!!*[/U] Here it is DANGEROUS!!! There it is not. Reason being...frequency!

Now how can something like frequency make it dangerous? Easily,in Europe they use the same voltage as we do...in some cases a little higher 2 make transmission over long distances possible. But the important differance is...they use 50Hz instead of 60Hz or Cps...the old terminology(cycles per second). Y is this important? Because your nervous system operates on the exact same frequency. 60 Hz! Now what this means is if you are shocked through your heart or brain if you are out of phase...in other words,if your positive touches negative of the same frequency it can unsyncronize your nervous system...causing your heart 2 go into arythmia.
Arythmia is when your heart beats irregularly,which can lead 2 cardiac arrest(heart stops beating). good for you,no good for me and definetly no good for the TOT's bcuz who's gonna step up to the plate to fill our shoes when we are gone? Hope this helps you guys in your quest for knowledge. Oh one vaild point comes to mind also...Also for exterior electrical usage,electrical code in all states(Federal Law) requires the usage of a GFI (ground fault interuption) electrical plug,mandatory for all areas where A/C may come into contact w/ water. You can get them in extension multi outlet plugs but they are expensive! Good luck and Happy Haunting!!!


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## 4nntt (Nov 28, 2006)

jaege said:


> The ground (the typically green or bare third wire) is included for the purpose of safty. Nominally, it is supposed to be attached to all metal components in the curcuit and then via various connections) back to the grounding strip in the panel box. Should the hot wire accidently come into contact with a metal part, it would short and trip a breaker, rather than remain live and zap the first sucker to touch it. I am sure that you have noticed that not all extension cords or electric appliances have such a grounding prong. So its not completely nessacary for proper operation. So long as you are certain not to strain the wires, and make sure that no bare wire is exposed ANYWHERE in the curcuit it should be okay. Of course I can say that because electricity is my friend. It may not be yours.


As Jaege said, the ground is a failsafe in case the voltage accidentally gets connected to the metal exterior of the device. You may notice however that your light is completely contained in plastic, making a ground unnecessary.

I hesitate to say go ahead and remove the ground pin from the extension cord though, in case if you ever use the cord for something else that should be grounded. If you can't get or use a regular two conductor extension cord, I'd recommend getting one of those little 3-prong to 2-prong adapters. That way you can simply remove it to use the extension cord later.


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## 4nntt (Nov 28, 2006)

Decrepit Desecr8shun said:


> Perfectly correct...but the word ground(often used by electricians) is an incorrect term for the whole thing....according to the lingo,"ground" is electrically the same as "neutral" in home & commercial. In reality,there is no such thing as either!...


Ground refers to the voltage potential of the ground you are on. Grounding something means to short it to this ground potential. Generally this is done either for safety or to provide a common reference between devices.

In AC power, the alternating voltage is generally only applied to one of the two conductors. the other conductor does not oscillate, and it referred to as 'neutral'.

You are right though, in home electrics especially, 'ground' and 'neutral' are often mistakenly referred to as the same thing.


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## Decrepit Desecr8shun (Aug 10, 2009)

BTW...thinking further on the subject,I realized I should add an addendum to that...Those rules about electricity (meaning how dangerous) only apply to low amperage circuits. ie:those provided for wall sockets. It doesn't apply 2 circuits designed for heavier loads(above 20amp rated breakers). Nor 240volt,440 or 660(transmission line) voltage level....Those will kill you in a different way...by cooking you! 

The short explanation is that a human body is made up by a large percentage of water...water is not naturally conductive in it's pure state. Rather,pure H2O is very non conductive....unfortunately pure is only found in labratory's not in the real world. We are also made up of carbon(the other large percentage_relative to the trace elements) and many other trace elements.
What this means is while the human body is conductive,it is also very high in resistance....the byproduct of resistance is heat...the larger the electrical charge(voltage/current or both) the greater the tendency to create heat as a byproduct which our frail little bodies do not handle well.... So the basic truth is electrocution is an incorrect term in all respects....You are not harmed by the electrocution unless you mean being cooked or having your nervous system disrupted. Hope that clarifies thing for you all.


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## fritz42_male (May 5, 2009)

If you do not have a ground plane then it is unlikely that a residual currrent detector (RCD) or earth leakage circuit breaker (ELCB) would be able to detect a fault and cut the power. This means possible fatalities!

ALWAYS keep the ground connected if it is there. I operate multiple RCDs to ensure total safety - you can get them on extension cord setups quite cheaply so no excuse not to use them.

Re the 50/60Hz issue, there are cases on record of people who have had shocks and got up and walked away and then died in their sleep that night because of the induced arrythmia


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## Decrepit Desecr8shun (Aug 10, 2009)

4nntt said:


> Ground refers to the voltage potential of the ground you are on. Grounding something means to short it to this ground potential. Generally this is done either for safety or to provide a common reference between devices.
> 
> In AC power, the alternating voltage is generally only applied to one of the two conductors. the other conductor does not oscillate, and it referred to as 'neutral'.
> 
> You are right though, in home electrics especially, 'ground' and 'neutral' are often mistakenly referred to as the same thing.


 I would advise you to hook up your oscilliscope to that socket so you may disprove your own theory on that point.. If you would like I can direct you to Norman Thaggert,head of Florida State University's Electrical engineering dept. (who was the lead engineer on 7 space shuttle flights) who will beg to differ that opinion. A little tech note on myself....my 1st official training was via the U.S. Navy where I was a Avionics Technician...I level. Then moving on 2 various other engineering jobs until finally going back to school seeking my masters(currently). Both of the neutral and the "ground" is the opposite leg of the "hot". And 1 question I have for you is, if one leg "Oscillates" meaning it alternates voltage/current___positive/ground to simplify so everyone understands then the opposite wire (neutral and ground)must be 180 degrees out of phase to complete the circuit. That is what A/C is...what you are refering 2 is pulsed direct current which what is a cheap half wave rectifier circuit puts out. There is no hot/ground/neutral or otherwise....that is dependant on the frequency that the current alternates. Those terms are those used 2 denote wiring for electricians...though somewhat educated in the matters of electricity(so they don't get themselves killed). They are not inclined 2 the science of electricity.


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## Decrepit Desecr8shun (Aug 10, 2009)

fritz42_male said:


> If you do not have a ground plane then it is unlikely that a residual currrent detector (RCD) or earth leakage circuit breaker (ELCB) would be able to detect a fault and cut the power. This means possible fatalities!
> 
> ALWAYS keep the ground connected if it is there. I operate multiple RCDs to ensure total safety - you can get them on extension cord setups quite cheaply so no excuse not to use them.
> 
> Re the 50/60Hz issue, there are cases on record of people who have had shocks and got up and walked away and then died in their sleep that night because of the induced arrythmia


Quite true and I commend u on a very good point...can't remember everything @ one time....very observant of you. Those cases are generally people that had nervous system disorders or were pre-disposed by natural arythmia or other heart conditions I would imagine. Guess I'll have 2 do some research. Damn,and my brain was tired from digital theory already!!! Man you people make me work!!!LOL!!!


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## Decrepit Desecr8shun (Aug 10, 2009)

Here's a link so you can better understand....






Be safe,have fun and most of all Happy Haunting


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## jaege (Aug 23, 2009)

While what Decrepit said is true, the (wrongly labeled) "ground" will short the system and trip a breaker (or blow a fuse) should the hot lead contact anything that it is attached to. The same holds true for the neutral. It too, will short the "hot" wire should the two touch, regardless of it being alternating current. Thats how the breakers (and fuses) are designed. You can actually safely touch the ground bar in the breaker panel in your house.(so long as you know what that is, and I am not advising you try this at home). For all intents and purposes it is dead. As to human death resulting, well, an old boss of mine used to check whether a curcuit was live by sticking his finger in the light socket. Got shocked numerous times. Only thing he ever got was a little jolt, but of course that is a 120 volt curcuit. He was an electrician and is still alive as far as I know. Or maybe he is undead, and we all know that electricity has little effect on a zombie. All of this is assuming there are no capacitors involved. Thats a whole different world.

All of that is beside the point. Normally I would not advise one to cut the grounding prong. Just get one of those adapters.


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## Decrepit Desecr8shun (Aug 10, 2009)

jaege said:


> While what Decrepit said is true, the (wrongly labeled) "ground" will short the system and trip a breaker (or blow a fuse) should the hot lead contact anything that it is attached to. The same holds true for the neutral. It too, will short the "hot" wire should the two touch, regardless of it being alternating current. Thats how the breakers (and fuses) are designed. You can actually safely touch the ground bar in the breaker panel in your house.(so long as you know what that is, and I am not advising you try this at home). For all intents and purposes it is dead. As to human death resulting, well, an old boss of mine used to check whether a curcuit was live by sticking his finger in the light socket. Got shocked numerous times. Only thing he ever got was a little jolt, but of course that is a 120 volt curcuit. He was an electrician and is still alive as far as I know. Or maybe he is undead, and we all know that electricity has little effect on a zombie. All of this is assuming there are no capacitors involved. Thats a whole different world.
> 
> All of that is beside the point. Normally I would not advise one to cut the grounding prong. Just get one of those adapters.


 I do the same as your boss,I've done alot of home/commericial electrical(dropped my liscense when I went back 2 school). NAFTA sent the vast majority of my careers 2 other countries! Like it said in my article...(maybe I should have explained further as there appears 2 be confusion on several points), the electricity has 2 cross your brain or heart 2 be fatal. Meaning from one hand to the other or your shoulder....or through your head 2 any point on your body. When those circumstances occur...head straight 2 your local emergency room...do not pass go...AND give me $200.00 for saving your life!!! ROFL!!!! Alright people,see you all 2morrow! I've got to hit the books!


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## 4nntt (Nov 28, 2006)

Decrepit Desecr8shun said:


> ... A little tech note on myself....my 1st official training was via the U.S. Navy where I was a Avionics Technician...I level. Then moving on 2 various other engineering jobs until finally going back to school seeking my masters(currently). ...


Boy, do I hope you are trolling.



Decrepit Desecr8shun said:


> ...And 1 question I have for you is, if one leg "Oscillates" meaning it alternates voltage/current___positive/ground to simplify so everyone understands then the opposite wire (neutral and ground)must be 180 degrees out of phase to complete the circuit. That is what A/C is......


The HOT leg oscillates between positive and negative voltage, not positive and 'ground', and is relative to the neutral leg, which in the main panel is actually tied to ground.

Here's a little light reading for you:

http://answers.yahoo.com/question/index?qid=20070529065141AAHUDWk






http://www.ab.com/drives/techpapers/rfignds.htm

http://www.epanorama.net/documents/groundloop/neutral_ground_separate.html


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## Decrepit Desecr8shun (Aug 10, 2009)

4nntt said:


> Boy, do I hope you are trolling.
> 
> The HOT leg oscillates between positive and negative voltage, not positive and 'ground', and is relative to the neutral leg, which in the main panel is actually tied to ground.
> 
> ...


Hmm,not trolling...here's an explanation for you...keep it simple and scientific please...not stooping 2 insults.

http://www.animations.physics.unsw.edu.au/jw/AC.html

Trying 2 keep it simple w/o a full dissertation on 3 phase electrical systems which most people don't understand....the neutral does the same is what I was pointing out. As for the "ground" wire it is a 60 degree out of phase leg w/55volts, leaving the other 2 legs "hot" as you said and "neutral" @ 120 degrees out of phase w/each other. That is something of a safety feature in modern electrical systems...those revamped in the last 30years. Most haven't been in less urban areas. Now,3 phase power is much less efficient @ everything including transmission,because you are not utilizing 100% of the available power at 120 degrees out of phase. Simply,that 
3rd phase kills potential because the other 2 legs are on the downward path looking at the o-scope trace...meaning around 80% efficency or a 20%loss before transmission lines or other(read that electrical devices) take their 20% toll as well. That 60degree out of phase leg exacts a heavy penalty for a marginal amount of safety.


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## 4nntt (Nov 28, 2006)

Decrepit Desecr8shun said:


> Trying 2 keep it simple w/o a full dissertation on 3 phase electrical systems which most people don't understand....the neutral does the same is what I was pointing out. As for the "ground" wire it is a 60 degree out of phase leg w/55volts, leaving the other 2 legs "hot" as you said and "neutral" @ 120 degrees out of phase w/each other. That is something of a safety feature in modern electrical systems...those revamped in the last 30years. Most haven't been in less urban areas. Now,3 phase power is much less efficient @ everything including transmission,because you are not utilizing 100% of the available power at 120 degrees out of phase. Simply,that
> 3rd phase kills potential because the other 2 legs are on the downward path looking at the o-scope trace...meaning around 80% efficency or a 20%loss before transmission lines or other(read that electrical devices) take their 20% toll as well. That 60degree out of phase leg exacts a heavy penalty for a marginal amount of safety.


Ah, but we're not talking about three phase electrical systems, we're talking about single phase home wiring, where the 'hot' wire ocillates relative to the 'neutral' wire.

Perhaps that is where you are becoming confused, as three phase circuits don't have a neutral at all, instead deriving power from the delta between the phase... each 120 degrees out of phase with each other.

Anyone following this thread please check the link I posted... you can read how standard home wiring works off a single phase oscillating on a single conductor relative to a second 'neutral' conductor which is tied to ground at a single point.

This may all seem academic to the point that home AC power is dangerous, but safety begins with a solid understanding of what you are dealing with.


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## jaege (Aug 23, 2009)

4nntt said:


> The HOT leg oscillates between positive and negative voltage, not positive and 'ground', and is relative to the neutral leg, which in the main panel is actually tied to ground.
> [/url]


Thats what I meant by it being safe to touch the neutral leg. Neutral and ground are electrically, the same, since they are connected together in the panel, and since, my good friend electricity, is lazy, it would rather travel through that nice copper wire than through you, unless you present a better conductor. I also carried an electricians license for a good number of years, although I could never bring myself to test a circuit with the finger in the light socket. Anyway, its been interesting conversing with you other electrical buffs.

Did at least one of us answer that question?


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## spinman1949 (Jun 29, 2009)

I could swear that if you stick a voltmeter on each leg of a 110 AC circuit to ground you get around 60 volts. Between the two legs you get 115 or thereabouts. This would lead me to believe you get zapped from either leg to ground. Am I right ?


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## 4nntt (Nov 28, 2006)

spinman1949 said:


> I could swear that if you stick a voltmeter on each leg of a 110 AC circuit to ground you get around 60 volts. Between the two legs you get 115 or thereabouts. This would lead me to believe you get zapped from either leg to ground. Am I right ?


Please, try it and post what you find (the voltmeter thing, not zapping yourself!).


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## Erebus (Jul 28, 2009)

Holy crap, I was just looking for a yes or no answer. I know a little about electricity. I have done alot around the house. But I have always hooked up a ground and that is why I was asking. I am not pulling the prong off. The wire are bare on the ends. It is just like any other light that you would put up in your ceiling. 3 wires, white, black, and copper. And since I am just using it one night, I was just trying to find out if I need to get a three prong plug, or if I could just use a 2 prong. The light will be mounted inside a wooden box (the mount will be on the inside roof) so the light it self will not be touching the ground, and a gel will go across the front so it will not get wet. There will be 2 holes in the back corners to let heat out. The way I always tell if there is electricity in a wire is I put my thumb on one wire, and ON THE SAME HAND I use my pointer and just swipe it across the other wire. If you use 1 pointer finger on a wire, and your other pointer finger on the other wire, then your in BIG TROUBLE.


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## Atribune (Oct 6, 2008)

short answer is " it's best to have a ground" and leave it at that lol


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## fritz42_male (May 5, 2009)

Absolutely.


For those who commented about 3 phase, how about the situation we have in older suburbs in Western Australia - my house is one one phase, next door is on another phase and next door to her is on the last phase!


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## 4nntt (Nov 28, 2006)

fritz42_male said:


> Absolutely.
> 
> For those who commented about 3 phase, how about the situation we have in older suburbs in Western Australia - my house is one one phase, next door is on another phase and next door to her is on the last phase!


I would imagine it's done the same way as the U.S, where each house then has one of the phases as the 'hot' and the neutral.


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## 4nntt (Nov 28, 2006)

NTX JK said:


> Holy crap, I was just looking for a yes or no answer. ... It is just like any other light that you would put up in your ceiling. 3 wires, white, black, and copper. ...


YES. If there's a ground wire, hook it up.


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