Liz0905: what do you mean?
meaning a 10W heating element is ideally what you should be using.
a 50W - and five of them at that seems to be (to the experts) waay overkill.
i'm a newbie as well, so would also be thinking along your thoughts of "why can't it be used at all" - but i guess there are all sorts of considerations of "under-powering" an element meant to be used for higher outputs.
especially with transistors, where (from what i understand) they are best used in full-on (saturated) or off conditions - the in-between is where a lot of energy is wasted (as heat).