| 摘要 |
The supporting mast is either of plastic e.g. glass fibre reinforced/epoxy resin tubing or of steel pipe with a resin coating. At its top a terminal box, in a mast head assembly, forms the centrepiece of the cross arms which are of weather resistant cast resin with bare conductors running through their centre from the anchor points of the overhead wires to the terminal box for the lead in. The end of the mast and the socket in the head assembly are polygonal, pref. twelve sided, to prevent the unit turning on the mast. The saddle for mounting the unit on the roof has threaded inserts cast in. Corrosion, etc. associated with metal roof furniture is avoided. |
