If {HEAD ~ a substantial amount} of cable is housed in {TAIL ~ the trunking}, there may be a tendency for it to push off the cover member thus exposing the cable 
If { HEAD ~ a substantial amount } of cable is housed in { TAIL ~ the trunking } , there may be a tendency for it to push off the cover member thus exposing the cable
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH