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SMc wrote:I tort it was grounded in case lightning strike- I coulda dream that though : (
maj. tom wrote:So I have noticed that in metal sink installations there is a ground wire attached to them somewhere. I understand that this is for safety in case somewhere along the line a hot wire touches the supply line... in metal pipes like in USA/Canada. But since we have PVC everything here, is there any use for the ground wire to the kitchen sink? If a hot wire touches a pvc connection it would just melt the pipe right?
What's the standard for TT? And what's the purpose? Also there is no hot water connection to the kitchen sink, so i can't figure it out, but then there's no ground wire on the bathroom sink. Why is the ground wire needed? Where should it be attached, the sink or the pipe? Why isn't there any on other household sink connections?
Please explain plumbers and electricians.
maj. tom wrote:So I have noticed that in metal sink installations there is a ground wire attached to them somewhere. I understand that this is for safety in case somewhere along the line a hot wire touches the supply line... in metal pipes like in USA/Canada. But since we have PVC everything here, is there any use for the ground wire to the kitchen sink? If a hot wire touches a pvc connection it would just melt the pipe right?
What's the standard for TT? And what's the purpose? Also there is no hot water connection to the kitchen sink, so i can't figure it out, but then there's no ground wire on the bathroom sink. Why is the ground wire needed? Where should it be attached, the sink or the pipe? Why isn't there any on other household sink connections?
Please explain plumbers and electricians.
nervewrecker wrote:Something I am having a hard time understanding and its best I ask here one time:
When you on the ground and you touch a conductor that is carrying current to ground you can get shocked. Arent, you at the same potential to ground and your internal resistance is more than that of the conductor? I understand you wont get the full dose but if you hold a current wire and not touching the ground you don't get shocked. Same way birds dont get shocked.
nervewrecker wrote:Something I am having a hard time understanding and its best I ask here one time:
When you on the ground and you touch a conductor that is carrying current to ground you can get shocked. Arent, you at the same potential to ground and your internal resistance is more than that of the conductor? I understand you wont get the full dose but if you hold a current wire and not touching the ground you don't get shocked. Same way birds dont get shocked.
Or vibratorGladiator wrote:If mama drop the hand mixer in the sink with water she go get shock boy.... you hadda put a grong in the sink so the breaker go trip.
maj. tom wrote:nervewrecker wrote:Something I am having a hard time understanding and its best I ask here one time:
When you on the ground and you touch a conductor that is carrying current to ground you can get shocked. and your internal resistance is more than that of the conductor? I understand you wont get the full dose but if you hold a current wire and not touching the ground you don't get shocked. Same way birds dont get shocked.
Well you're right, as far as I understand it also.
If you touch a ground wire that's carrying current to the ground you can get a shock if you are in direct uninsulated contact (barefoot) with the ground. Some amount of current will flow through you and the ground if you are barefoot because you are creating an electrical potential difference between two points. When you are in contact with the ground barefoot you are not really grounded at the same potential as the ground because you are mostly made of water and that creates resistance and thus a potential difference in the circuit. Most of the current will continue to flow in the ground wire. But it only takes 0.1 A flowing across the heart's sinus node to cause atrial fibrillation and a heart attack. If you're wearing proper insulated work boots it should not happen. Always check that your boots are not penetrated by a nail or anything metal. Also there's a standard in the depth they use for ground rods for a reason. http://www.cpuc.ca.gov/gos/GO95/go_95_rule_59_4.html
Current can only flow when there is an electrical potential difference between two points. A bird can't get shocked because all the touching points are the same voltage. If the bird's wing touched another wire while sitting on the bottom wire, it will fry. Because potential difference.
Grounding really means equalizing the voltage across two points. You ever saw videos of helicopter linemen grounding off by attaching the wire to the helicopter first? They're equalizing the voltage across those two points, so now the lineman has no potential difference between him and the wire.
An airplane has static wicks/pins attached all over points on the body and wings that discharges any buildup of electricity that occurs due to lightning or just due to a metal object moving through a magnetic field. The fuselage is designed to act as a Faraday cage to protect everything inside. After a lightning strike they will ground the plane and go over every system with a fine tooth comb before allowing it to fly again.
I never really studied the topic as I'm not an electrical engineer, so disclaimers on that, and willing to be corrected by those who know better.
maj. tom wrote:aye i read of people getting killed from microwave oven capacitors eh. Capacitors like that can hold charge for days after you unplug them. Things like computer power supplies and stuff need to be grounded and then capacitors discharged before working on them. I imagine larger appliances like refrigerators and ac units have even bigger capacitors. Make/buy a discharge tool and always discharge capacitors. It's just a 1MΩ resistor soldered on a piece of wire to make a closed circuit with the two prongs of the capacitor.
rspann wrote:So he fully charged then?
nervewrecker wrote:One for the techs in here.
3 phase system, red, yellow and blue wires.
The main breaker supplies 2 3 pole breakers for isolators, one for air handler and one for condenser.
Condenser has a double pole contactor supplying split phase induction type fan motor and three phase compressor, blue line hooked up direct with a lug, red and yellow on line side of contactor, red and yellow on load side of the contactor.
Fan works with yellow wire disconnected from load side of the contactor, contactor coil not energised, not closed.
Works only when condensor isolator is turned on.
Leme hear allyuh...
So my friend you and some of the other posters have the general gist, but allow me to clarify a few areas which should help younto understand grounds...maj. tom wrote:nervewrecker wrote:Something I am having a hard time understanding and its best I ask here one time:
When you on the ground and you touch a conductor that is carrying current to ground you can get shocked. Arent, you at the same potential to ground and your internal resistance is more than that of the conductor? I understand you wont get the full dose but if you hold a current wire and not touching the ground you don't get shocked. Same way birds dont get shocked.
Well you're right, as far as I understand it also.
If you touch a ground wire that's carrying current to the ground you can get a shock if you are in direct uninsulated contact (barefoot) with the ground. Some amount of current will flow through you and the ground if you are barefoot because you are creating an electrical potential difference between two points. When you are in contact with the ground barefoot you are not really grounded at the same potential as the ground because you are mostly made of water and that creates resistance and thus a potential difference in the circuit. Most of the current will continue to flow in the ground wire. But it only takes 0.1 A flowing across the heart's sinus node to cause atrial fibrillation and a heart attack. If you're wearing proper insulated work boots it should not happen. Always check that your boots are not penetrated by a nail or anything metal. Also there's a standard in the depth they use for ground rods for a reason. http://www.cpuc.ca.gov/gos/GO95/go_95_rule_59_4.html
Current can only flow when there is an electrical potential difference between two points. A bird can't get shocked because all the touching points are the same voltage. If the bird's wing touched another wire while sitting on the bottom wire, it will fry. Because potential difference.
Grounding really means equalizing the voltage across two points. You ever saw videos of helicopter linemen grounding off by attaching the wire to the helicopter first? They're equalizing the voltage across those two points, so now the lineman has no potential difference between him and the wire.
An airplane has static wicks/pins attached all over points on the body and wings that discharges any buildup of electricity that occurs due to lightning or just due to a metal object moving through a magnetic field. The fuselage is designed to act as a Faraday cage to protect everything inside. After a lightning strike they will ground the plane and go over every system with a fine tooth comb before allowing it to fly again.
I never really studied the topic as I'm not an electrical engineer, so disclaimers on that, and willing to be corrected by those who know better.
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