Tingle from metal lamp = dangerous?

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My electrical theory is fair but not great. Can someone please advise me.
I have an old Anglepoise lamp with painted metal arms and painted metal lampshade (Anglepoise model 90). It has a two-core mains lead. I am in the UK so this is all at 230-240 volts.
Today I touched the outside of the lampshade and got a sort of vey mild tingle feeling which felt "odd". When I used a mains tester screwdriver on the exposed metal (at the joint of the lampshade and support arm) then it glowed as if the metal of the Anglepoise lamp was live.
I unplugged the lamp and tested the resistence between the live pin on the mains plug and some exposed metal on the lamp. I got no resistence reading at all (i.e. it must have been a very high resistence). I then tested the neutral pin in the same way and got the same high resistence result.
So the lamp seems ok. But something seems to be wrong!
QUESTION: Is my lamp safe to use and could I get a shock from it in its present condition?
QUESTION: If my lamp is unsafe then is there a repair I can do?
Thank you for any info. Lars
-----------------
PS: Picture of Anglepoise model 90:
http://www.anglepoise.com/timeline/model_90.jpg
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No. Yes.

I would guess that the insulation is failing somewhere. Your test with the meter wasn't high voltage and didn't show it up. You need proper equipment to do that test.
I would guess that replacing all the wiring would probably do it. It *might* be the lamp holder, but I'd change the wiring first. If you do replace the lampholder, it's probably a special heat resistant one (probably ceramic).
--
Bob Eager
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snipped-for-privacy@x.x says...

That's because you were measuring it at a few volts - you need to measure at a few hundred volts.

Probably not very safe - you already had a mild shock from it.

Find the loose wire or damaged insulation and replace it.
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wrote:

Do you have nylon carpets?
--
Peter Parry.
http://www.wpp.ltd.uk/
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We have an Art Deco brass lamp which I can feel 'tingling'or 'trembling' when I touch the base or the stem. The wiring has been checked and renewed several times and it still happens - and Spouse is absolutely thorough about doing a good job mainly to prove me wrong because he can't feel it. I can still feel it.
I could also, once upon a time, feel the same thing from a metal electric kettle and nobody else could. The kettle was taken away by the first child to go to university. Over the years we lost all our electric kettles like that which is why we're left with an ancient copper one on the gas hob, it used to be used by Spouse's grandmother on their coal fire. But that's a different story.
It's not a shock and it can only be felt with the lightest possible touch - but it's very definitely there and can only be sensed when the lamp is plugged in and the outlet switch is on. The lamp itself doesn't have to be lit.
I've never suffered and I doubt that the OT will either. If he were going to he would have done by now.
Mary
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On a sunny day (Wed, 27 Apr 2005 21:48:01 +0100) it happened "Mary Fisher"

It is a common case, and possibly capacitive coupling between the hot wire and the metal frame (if no isolation problem). The responsible things to do is use a 3 lead mains cable and plug, and connect the ground to the metal frame. Problem solved. ANY other configuration will leave the possiblity of a short between a live wire and the frame, causing the metal to become live. When ground is connected a short will blow the fuse.
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Nope. That's what Spouse said. It now has that (he did it) and there's no change..
Mary
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Then it is probably not being plugged into a properly grounded outlet.
At the very least, you should have him install a GFI outlet in the place that the lamp is used. Better is to make sure that the safety ground on the outlet really has a good, low impedence run to the main breaker box.
Of course, he may have failed to properly connect the safety ground to the metal parts of your lamp. :)
--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
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vey
tester
Anglepoise
Once had lots of problems like this, and when i got a shock off the earth I did something about it. It turned out lots of the various earth connections around the house were just copper cable twisted together, so of course the joints had gone high R over time. Also the earth rod was disconnected, so there was no E anywhere anyway. Just glad there was no shower.
NT
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Mary Fisher wrote:

Following fitting the earth connection, does it tingle even when switched off at the wall socket?
If so , it sounds like you are discharging a static charge into the lamp, rather than getting a charge from it. Touching something that is earthed (eg wall radiator) shortly before touching the lamp should prove/disprove this. But don't touch the two at the same time until you have had the lamp professionally tested for safety - I wouldn't have trusted my hublet with anything electrical..
--
Sue






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In that case it may be advisable to check that your 13amp socket has a good earth.
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On a sunny day (Wed, 27 Apr 2005 22:20:56 +0100) it happened "Mary Fisher"

Well, I was in this house once, where they also earthed the stuff, but it then turned out the earth (I had to install some equipment there) was not connected to anything, it was originally connected to water pipes, but somebody had just cut the wire. You (he) can test if earth is there with say a 40 W lightbulb between earth and live. It should light. Then test between live and your lamp frame, it should light too. The only alternative is that you pick up something from the floor (bad wiring conductive carpet), anything goes.
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please
painted
mains
of vey

tester
lampshade
Anglepoise
live
got
high
and
from it

do?
Its not safe... how good your meter is and how good you are using are open to question..but the tingle is proof positive you have some degree of short or current leak in the lamp wiring to the lamp base metal. Rewire it.
Phil Scott

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Wire is cheaper than a coffin and funeral.

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Certainly not safe. It sounds like the insulation is breaking down under mains voltage.

Get the wiring replaced and the bulb holder inspected.
sponix
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Does it have an earth (ground) prong too?

If you get a continuous tingle, then it's _highly_ unlikely to be a capacitive/inductive/static leak (as others have suggested).
Last time I touched a device and got a minor tingle, repeating that test while holding on to something grounded was something I'm not going to repeat. That hurt! Dumb me. At least we're only 120V...
You say "old", and the picture shows that the wiring in the lamp is being moved whenever you adjust the lamp. Possibly abraded and the conductors may now be intermittently contacting the frame.
I recommend removing the wiring and inspecting both it and the lamp socket as others have suggested. The socket may need cleaning. If you see worn spots in the wiring, replace it.
If you don't see any obvious worn spots, now you really worry about the fixture.
Measuring resistance won't be particularly reliable, fancy equipment or not, because if you have a bare spot on the wiring in the arms, the slightest bit of movement may break/make the connection.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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I'd strip it down and check it thoroughly, and if you're still not happy, destroy and dispose of it safely. Better still, pass it on to trading standards in case it has a design flaw.
I must point out though that it is rare for UK approved double insulated appliances to fail and present a shock hazard. If you find a design fault which could have contributed to the case becoming live, be sure to report it to trading standards so it can be investigated.
Is it a constant tingling feeling or a momentary minor jolt? It's very common to get static discharges to metal appliances, but there's also an odd gentle 'vibrating' or 'buzzing' sensation which can sometimes be felt touching the metalwork of double insulated appliances. These are perfectly harmless phenomena.
Dave
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Ah! Thank you :-)
That's exactly the effect from my art deco lamp but everyone else seems to think it needs seeing to. It has been seen to.
Mary

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Lars, to check the leak resistance of mains circuits you need a special "megger"meter.This is usually in the range of Mohms, so usually a normal multimeter shows infinite resistance (sometimes modern digital ones are capable of measuring this resistance).It's very dangerous to use something that gives you (even) a slight shock.If you find it's too much money to have it professionaly repaired (maybe a worn out cable that touches the frame?) then better trash it, than put your life in danger.
-- Tzortzakakis Dimitrios major in electrical engineering, freelance electrician FH von Iraklion-Kreta, freiberuflicher Elektriker dimtzort AT otenet DOT gr

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On Thu 28 Apr 2005 09:44:56, s--p--o--n--i--x wrote: <

What does "double insulated" mean in actual practice?

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