I currently have 5 x 20W halogen bulbs attached to two AC 12V rails, and an AC transformer (105VA).
I'd like to replace existing five bulbs with five LEDs, e.g. these: 7.5W (update: 12V AC) (Equivalent halogen 43W).
My initial understanding (also supported by this question) was that the required power for such setup would be 7.5W * 5 = 37.5W, and therefore the existing transformer would work fine. However, the seller's website has this manual which basically states that in my calculations I need to use equivalent halogen power (i.e. 43W) rather than 7.5W. That would mean that the existing transformer wouldn't be sufficient.
I struggle to understand why equivalent halogen power should be used here instead of simply the bulb's power. Can anyone advise on this please?
Best Answer
With the additional information provided these 12v lamps are designed to work with standard halogen 12v fixtures since your wattage of the new lamps is less than the wattage of the halogen yes they will work. It looks like 1/2 the wattage so there is the savings and in my experiance you will have more light or perceived light because light meters read light we cannot see where LED's produce light in a narrow band with so power is not wasted.