Is My Lamp Grounded?

Hi,
how can I easily test if my metal-lamp is properly grounded?
Thanks for every help,
Omar
Reply to
Omar Elschatti
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Do a contuinty test from ground to the lamp while it is plugged in.
Reply to
Greg-EE
2 pronged plug? not grounded, 3 prong plug maybe. With the lamp disconnected use an ohm meter from each conductor to the frame. This will at least tell you if it isolated. If there are 3 wires then one will read continuity.
My uncle had a house north of Paris, FR. All the lighting was 220v there was a metal parlor lamp that with bare feet, and touching it shocked me. Uncle's solution was to wear slippers and place the lamp on a rug.
Reply to
Zathera
Unplug the lamp and see if there is a 2-prong plug on the end of the cord or a 3-prong. The long prong on the 3-prong is the ground. If it is not a 3-prong, it is not grounded. If it is a 3-prong, while it is unplugged, make a continuity check from the gound on the receptacle to the metal lamp surface. If there is no continuity, it is not grounded when plugged in.
Reply to
indago
A contuinity test will indicate if there is contuinity between two points. If the grounding conductor is damaged, or frayed, at any point, it could leave a situation where just one small strand of a 16 ga., or smaller (lamp fixture), wire is still connected, and such a test would indicate contuinity leaving you to believe all is well. If the integrity of the grounding path is important to you an additional test under load should be conducted.
Louis-- ********************************************* Remove the fish in address to respond
Reply to
Louis Bybee
This is related but does not answer your question. By the NEC metal floor lamps and table lamps do not have to be grounded. They are commonly and legally supplied by a two wire cord. In about 1984 a couple in Anchorage, Alaska purchased a metal floor lamp from a discount store. They assembled the lamp using the screws that came with the lamp. When three legs were attached to the metal post with the screws one screw had unknowingly caught the hot wire that run inside the metal post. Some 8 months later their infant girl was playing on the rug and came into contact with the lamp and a metal baseboard heater and was electrocuted. The trial revealed that the lamp was not listed. How does the famous National Electrical Code deal with this? Well several proposals were made to require a grounding conductor with the two circuit conductors to ground metal portable lamps. The Code panel flatly rejected the proposal stating that, "There is not sufficient reason to make such a drastic change to a long established practice that would be a major cost to the lamp manufacturers."
And there is the NEC CYA in 410.45 Tests. "All wiring shall be free from short circuits and grounds and shall be tested for these defects prior to being connected to the circuit."
This has been in the Code for the last 15 years. Obliviously, the couple that assembled their lamp did not test it for short circuits and grounds. Of course, everyone knows how to do this!
This and the failure of a NEC Code Panel to require brown orange yellow for 480 volt three phase circuits after over 500 electricians testified to the dangers of not identifying 480 volt circuits has made me realize that the NEC places a high price on safety.
Reply to
Gerald Newton
On Sat, 27 Sep 2003 04:29:19 GMT, "Gerald Newton" Gave us:
But it MUST be a PHASED type "plug", and it must be properly wired such that the neutral phase is tied to the lamp body.
Reply to
DarkMatter
Definitely NOT. The Neutral conductor is a current carrier, and is not to be used as a ground. If the lamp is to be grounded, it must be grounded with a separate GREEN conductor, and a 3-prong plug attached.
Reply to
indago
Dead wrong, DimBulb.
A polarized (not "phased") plug ensures that the screw shell of the bulb connects to neutral, but it does NOT ground the lamp frame.
The metal lamp frame is left floating unless the lamp is provided with a 3-wire grounding cord containing a separate green ground wire. Connecting the neutral to the lamp frame is poor practice, an NEC violation, and a serious safety hazard!
Bob Weiss N2IXK
Reply to
Bob Weiss
On Sat, 27 Sep 2003 04:29:19 GMT, "Gerald Newton" Gave us:
But it MUST be a PHASED type "plug", and it must be properly wired such that the neutral phase is tied to the lamp body.
Reply to
DarkMatter
On Sat, 27 Sep 2003 12:08:47 GMT, indago Gave us:
Did you even read the statement he made? TWO conductor line cords ARE acceptable for lamps. IN THAT CASE, a phased type two prong plug IS used, and the neutral line IS the grounded element.
Got clue?
Reply to
DarkMatter
On Sat, 27 Sep 2003 14:02:43 GMT, Bob Weiss Gave us:
The "lamp frame" and the bulb "screw shell" ARE common on every metallic lamp I have EVER examined. Try again.
This is precisely the reason that phased type plugs and receptacles were introduced. IN fact, there was a time when a simple hand held drill was a two wire metallic cased affair, with one line connected to the shell. Put the plug in the wrong way on a concrete floor in bare feet, and give it a try. Please.
Reply to
DarkMatter
On Sat, 27 Sep 2003 14:02:43 GMT, Bob Weiss Gave us:
Guess you'd better run out to all those manufacturers, and tell them then!
Reply to
DarkMatter
Then the one that you "examined" was improperly wired.
Reply to
indago
As usual, you're an idiot. I hope no one here is taking your advice! The metal enclosure of any appliance is *NEVER* connected to neutral! That is an unacceptable health risk!
As always, what a maroon!
Sure, we've just given it to you free of charge. Now go away and stop trying to kill people!
Reply to
Keith R. Williams
On Sun, 28 Sep 2003 02:17:29 GMT, indago Gave us:
To Quote Mr. Newton:
This is related but does not answer your question. By the NEC metal floor lamps and table lamps do not have to be grounded. They are commonly and legally supplied by a two wire cord.
endquote.
What is says is that the old way is still acceptable.
What is does not say is that a phased or "polarized" plug is required these days, and the outlets in ALL installations must also be of the polarized variety as well. This ensures that at least the line gets connected the same way every time.
If a metallic lamp ever shorted its "hot" lead over to the body of the lamp, I for one, would want the neutral to be common to that lamp body as THAT would cause a breaker to disrupt the line. Without such grounding, a two wire style lamp could have a faulty condition where the "hot" lead is connected to the lamp body. This is unacceptable. What it says is that if one "full floats" the body of the lamp, either lead could end up connected to it. If that lead is the neutral, not much to worry about, if the lead is the "hot", then suddenly, the consumer product is rendered potentially deadly.
In the case where the neutral is tied to the lamp body, such a potential hazard could not exist as a "hot" side connection would cause a shorted condition causing the line breaker to open, which is the desired effect.
This is related but does not answer your question. By the NEC metal floor lamps and table lamps do not have to be grounded by a three wire cord. They are commonly and legally supplied by a two wire cord.
Explain to us now, how leaving the lamp body open on a two wire line cord style metallic lamp is "safe".
Reply to
DarkMatter
On Sat, 27 Sep 2003 23:10:18 -0400, Keith R. Williams Gave us:
No, that is how one describes you, keith.
On a three wire attached device, I agree, however...
This discussion is about items which are wired with a two prong cord, dipshit.
You are lacking, boy. You lack brains, mainly.
You're an idiot. You do not warrant further response, troll boy. Go away.
Reply to
DarkMatter
Not to mention being illegal.
Consider a two-prong plug that is partly pulled out of the wall so that one conductor makes contact and the other doesn't.
Assume it's the hot that makes contact and that the lamp in turned on.
Further assume that the lamp is wired in the unsafe and illegal manner described in the statement
"The 'lamp frame' and the bulb 'screw shell' ARE common on every metallic lamp I have EVER examined."
The metal portions of the lamp will be at full live voltage with only the resistance of a 100W light bulb between the person who touches the lamp and hot.
Touch that lamp with one hand while touching something grounded with the other and you could be killed.
If the individual who gave the unsafe and illegal advice above won't stop on his own, I suggest that someone post a periodic FAQ to warn the unwary that deadly advice is being posted.
Reply to
Guy Macon
On Sun, 28 Sep 2003 08:24:48 +0000, Guy Macon Gave us:
ANY two prong lamp can be "plugged in" incorrectly. Since plugs are design to break contact with both conductors together, your schema is difficult to reproduce.
In any event, any two prong lamp can be as dangerous as you describe, whether one leg is common to the lamp body or not. A fault could allow connection of either side of the line to the lamp body. So with an unconnected frame, the same dangers exist. The likelihood that a plug is pulled out part way is less than the likelihood that a shorted hot lead on a grounded frame would occur.
On a grounded frame, the breaker opens. ON an ungrounded frame, your "dangerous" "hot lead" condition could occur, just the same without some lame "partially plugged in" circumstance.
It should be disallowed by the NEC completely, and three prong plugs should be required on any metallic framed device, period.
Don't any of you remember the old metal cased hand drills with non-polarized plugs? PLugged in one way, they were fine. Reverse the plug, and safety goes out the door, and danger steps in. This is the entire reason that electrical hand tools were changed to plastic shelled devices, and the entire reason that outlets and plugs were changed to polarized types.
Y'all had better analyze this a bit more than just disclaiming my remarks, because if the NEC still allows two pronged cords on metallic devices, there IS a problem, no matter how it gets wired.
Reply to
DarkMatter
"the old metal cased hand drills with non-polarized plugs" were never wired with a conductor fastened to the case. If one of the conductors did touch the case, it was because of a breakdown in insulation or broken wire. Those old metal case drills were much abused by workmen and in the later years a 3-prong plug was required with the green grounding wire fastened to the case. Also, the newer electric tools are made of high impact plastic, and the use of 2-prong plugs on a 2-wire cord is used because there is no danger of handling metal parts that could become live during use.
Reply to
indago

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