i put a teather kill switch on my z400 and every time you pull the teather to kill it the fuse by the battery blows anybody no if this normal thanks for any help.

 

Sounds like you got your wires crossed. When tethered is pulled, it should create a ground. Sounds like you got a hot wire turning into ground when pulled thus blowing a fuse. You can wire it up hot also, so when the tethered is pulled it breaks the current.
Hope this helps.