Is this just plain dangerous?

[Kingston]

I bought this cheap workshop lamp and didn't expect much but what the heck.

http://www.netanttila.com/webapp/wcs/stores/servlet/ProductDisplay?productId=734266&storeId=1444&catalogId=1444&shopId=10008&compartmentId=10064&categoryId=36651

The plastic parts started breaking quite soon to the point it became unusable. Then it turns out it practically eats those halogen light bulbs as if gasoline to make it run. I decided to take it apart and see if I could harness it into something that works.

The lamp has no fuse. It has a heavy transformer for a lamp. The secondary delivers 20W 12VAC for the halogen bulb.

But this is delivered RAW through those metallic telescope holders! A part that is meant to be touched when adjusting the height. I certainly did this plenty of times.

Shouldn't this deliver an electric shock and isn't it quite dangerous? The transformer secondary is always live and open to touch. And how would something like this ever get approved by any regulation?

 

[JohnRoberts]

There may be a fuse inside the transformer. If it is agency approved, they would test such an obvious short circuit possibility. ULs main concern in this case would probably be that it doesn't start a fire. They are perfectly OK with it self destructing.

12VAC is relatively low voltage in the context of typical skin resistance, you might feel something with sweaty hands. A jewelry chain or any piece of conductive metal in the vicinity could short across those powered struts. If not fused it could start a fire. 

Note: A fuse inside the transformer is not easy to replace so I would be careful about shorting the output to test it.

If it is not agency approved, I would rethink using it without modification. You could always add a fuse. Or throw it away. 

JR

 

[Andy Peters]

But this is delivered RAW through those metallic telescope holders! A part that is meant to be touched when adjusting the height. I certainly did this plenty of times.

Shouldn't this deliver an electric shock and isn't it quite dangerous? The transformer secondary is always live and open to touch.

It's low voltage and it can't shock you.

But along these lines, I used to have some fun lighting built around a run of a parallel pair of wire ropes (separated by a few inches), maybe the 1/8" thick stuff you get at the hardware store. Using simple test leads with alligator clips on each end I suspended some low-voltage 20W halogen bulbs. The wire rope lines were connected to some big honkin' mains transformer that gave lots-o-watts at 12V. The transformer was mounted high up on a shelf in a box with a mains fuse and a power cord. It's basically the DIY version of the same setup you see in some restaurants or wherever.

The wire itself was uncoated.

The transformer vanished in a move. Similar safety-approved transformers for things like walkway lighting are at the local hardware/home-improvement store but they're quite expensive.

-a

 

[Kingston]

Thanks for the information both of you. I suppose it's no different from slot car racing and similarly open secondaries right on the fingertips of small children.

But this definitely has no place on an electronics workshop table. I have enough open transformer windings and dangling wires without some stupid lamp! And this fast burning of halogens needs to stop too. Apparently they don't like even 5% over voltage.

I like the form factor so it's insulation and cheapo DC regulation time!  ;D Awfully refreshing to have such a simple project for a change.

 

[tv]

As JR said, there -may- be a fuse inside the trafo, some such trafos had a thermo-sensitive gizmo inside that would break the circuit if overheated (which would happen when shorted) ...

But I have also seen -studio- instalations with halogens hanging off raw, uninsulated copper wires. Hey, it's low voltage after all.

Perhaps some insulating tape would fix that?