Another bad desktop lamp
In this article we examine another desktop lamp which is available in many shops , for example in the stores of the "Ikea" chain.
The lamp has a simple style, it is almost entirely made of metal, and it is quite robust.
Negative aspects
The first problem of these lamps is that they work with the 120 or 230 V AC voltage from the wall socket. The wires go through the empty metal bars, one wire per bar, and reach the halogen bulb.
Since this is a table lamp, the head of the lamp is at about 20 cm from the head of the person that is sitting at the table, and it can be even nearer when the lamp is used to illuminate a smaller area.
Then the user gets the high electric field of AC type that comes from the lamp's head.
The electric field near the rods is very small because they shield the internal wire, but the halogen bulb of course is not shielded.
The current in the wires is noticeable since the halogen lamp has a power of 40 W, then there is also a noticeable magnetic field, of AC type.
The halogen lamp creates also a lot of heat, for this reason there is a warning on the product's package, and in the usage instructions, that says that the head of the lamp must be at least 50 cm from any object, and that the lamp can cause a fire if left too near to something.
Besides the discomfort caused by the excessive heat, and the risk of fire, this fact also increases the problems of the electromagnetic emissions, because the user will adjust the lamp's head higher to keep it at 50 cm from the desk and so the lamp's head will be nearer to the user's head.
Other problems
This lamp has also a problem caused by the missing ground connection. The plug has only two contacts, the ground contact is missing. The metal frame of this lamp is almost one meter long, and it is made of two parallel tubes. In the presence of radio frequency electromagnetic fields the lamp collects radio waves and radiates them again. The metal frame should at least be connected to ground to avoid this.
Conclusions
One may say that this happens because it is a very cheap product, but it's not so. From the mechanical and aestethic point of view this product is quite good, and the electrical connections are totally safe. The problem is always that the designers do not know and do not understand the danger of electromagnetic emissions. Even if the designers of this product had knowledge of the effects of EMF the only way to avoid the EMF from this lamp would be to power it with smooth DC voltage, which is very difficult to achieve at high voltages, converting the AC voltage.
We have modified one of these lamps with LEDs powered by a filtered DC of just 5 V, and the results are very good.