inlet heat (wiring)

[Flash Arghhh]

hi,
well just found that the cabling that runs on top on my inlet manifold, to my injectors and the rest of the engine bay, has melted due to the heat from the inlet manifold (it has been touching it).

i'm just wondering if any one else has had this problem? does is sound like this is right and how hot does a inlet get?

cheers flash