I am very new in the lighting arena but I was wondering why do lighting companies use aluminum spikes? It makes no sense to me at all. After 1-2 yrs they are completely rotted and the entire fixture needs to be replaced from the service jobs I have went to look at. Why doesn't every company use a non-metal spike? The PVC spikes make the most sense. Do the copper, brass and bronze spikes rot as much as the aluminum?