Electricity (Hazards From Trees) Regulations 2003

The regulations set out the circumstances in which the network company or we may warn you of a tree encroaching a specified zone, or the circumstances where the network company or we must give a "cut or trim" notice to you.  The purpose of a cut or trim notice is to notify you (the tree owner) that a tree is encroaching a growth limit zone and must be cut or trimmed.

If you receive a cut or trim notice, it will contain all the information you need to comply with the regulations, including:

A tree owner commits an offence if he or she is given a cut or trim notice in relation to a tree that requires the tree owner to cut or trim the tree, and the tree owner:

You can view these regulations in their entirety here.