determined by arbitration in accordance with article 42 (procedures in relation to certain approvals  etc.).  81.  The plans submitted to National Grid by the undertaker pursuant to paragraph 74(1) must be  sent to National Grid Plant Protection at plantprotection@nationalgrid.com or such other address  as National Grid may from time to time appoint instead for that purpose and notify to the  undertaker.  82.  For the protection of the utility undertakers referred to in this part of this Schedule, the  following provisions have effect, unless otherwise agreed in writing between the undertaker and  the utility undertakers concerned.  83.  In this Part of this Schedule—  “alternative apparatus” means alternative apparatus adequate to enable the utility undertaker in  question to fulfil its statutory functions in a manner not less efficient than previously;  “apparatus” means electric lines or electrical plant (as defined in the Electricity Act 1989),  belonging to or maintained by that utility undertaker;  “functions” includes powers and duties;  “in” in a context referring to apparatus or alternative apparatus in land includes a reference to  apparatus or alternative apparatus under, over or upon land; and  “utility undertaker” means—  for the area of the authorised development, and in relation to any apparatus, means the utility  undertaker to whom it belongs or by whom it is maintained.  84.  This Part of this Schedule does not apply to apparatus in respect of which the relations  between the undertaker and the utility undertaker are regulated by the provisions of Part 3 (street  works in England and Wales) of the 1991 Act.  85.  Regardless of the temporary prohibition or restriction of use of streets under the powers  conferred by article 13 (temporary prohibition on restriction of use of streets and public rights of  way), a utility undertaker is at liberty at all times to take all necessary access across any such street  and to execute and do all such works and things in, upon or under any such street as may be  reasonably necessary or desirable to enable it to maintain any apparatus which at the time of the  prohibition or restriction was in that street.  86.  Regardless of any provision in this Order or anything shown on the land plans, the  undertaker must not acquire any apparatus otherwise than with the prior written agreement of the  utility undertaker.  87. —(1) If, in the exercise of the powers conferred by this Order, the undertaker acquires any  interest in any land in which any apparatus is placed or over which access to any apparatus is  enjoyed or requires that the utility undertaker’s apparatus is relocated or diverted, that apparatus  101 Notices  PART 7  FOR THE PROTECTION OF UK POWER NETWORKS LIMITED, LONDON  POWER NETWORKS PLC AND SOUTH EAST POWER NETWORKS PLC  (a) UK Power Networks Limited, whose registered office is at Newington House, 237  Southwark Bridge Road, London, SE1 6NP;  (b) London Power Networks plc, whose registered office is at Newington House, 237  Southwark Bridge Road, London, SE1 6NP;  (c) South Eastern Power Networks plc, whose registered office is at Newington House, 237  Southwark Bridge Road, London, SE1 6NP; 