scope:

PURPOSE AND SCOPE

This TGN gives guidance on the structural capacity of overhead line towers to accept mobile phone antenna installations without encroaching upon the minimum structural reliability required of such towers.

Mobile phone installations comprise of cellular antennae, microwave dishes, wave-guides, feeders and the steelwork associated for attachment to the tower, which add appreciably to the tower wind loading especially where multiple installations are involved. This TGN is applicable to towers of types L66, L2, L3, L6, and L8. No other towers are suitable for installation.

This TGN assumes that tower foundations have been upgraded to be compatible in strength with their tower superstructures. If there is no record or written proof of this, increase site wind speed, VB, by 8% when determining the suitability of the proposals. This is explained further in Appendix A.

The TGN also assumes that all towers are modified in accordance with TDC 161 and TGN(E) 863. Un-modified towers shall not be considered for cellular installations unless modifications are carried out. However, this shall be agreed with Asset Strategy

The calculations taken from BS 8100 assume the feeders are installed inside the tower leg. To install the feeders on the outside of the tower leg, or on the structure itself, would increase the wind loading. For guidance on installing the feeder in a position that is not covered in this document, refer to Asset Strategy - Asset Policy.