Comece analisando o código diretamente.
National Electrical Code 2014
Chapter 2 Wiring and Protection
Article 210 Branch Circuits
210.52 Dwelling Unit Receptacle Outlets.
(C) Countertops. In kitchens, pantries, breakfast rooms, dining rooms, and similar areas of dwelling units, receptacle outlets for countertop spaces shall be installed in accordance with 210.52(C)(1) through (C)(5).
(1) Wall Countertop Spaces. A receptacle outlet shall be installed at each wall countertop space that is 300 mm (12 in.) or wider. Receptacle outlets shall be installed so that no point along the wall line is more than 600 mm (24 in.) measured horizontally from a receptacle outlet in that space.
Exception: Receptacle outlets shall not be required on a
wall directly behind a range, counter-mounted cooking
unit, or sink in the installation described in Figure
210.52(C)(1).
Então, se você tivesse uma bancada reta de 28 ', sem pias, fogões, geladeiras, etc. Então, você precisaria de pelo menos 7 tomadas de receptáculo, se quisesse ser compatível com código.
Se, no entanto, você tiver pias, fogões, refrigeradores, etc. Em seguida, cada pedaço da bancada será considerado seu próprio espaço separado no balcão.
(4) Separate Spaces. Countertop spaces separated by rangetops, refrigerators, or sinks shall be considered as separate countertop spaces in applying the requirements of 210.52(C)(1). If a range, counter-mounted cooking unit, or sink is installed in an island or peninsular countertop and the depth of the countertop behind the range, counter-mounted cooking unit, or sink is less than 300 mm (12 in.), the range, counter-mounted cooking unit, or sink shall be considered to divide the countertop space into two separate countertop spaces. Each separate countertop space shall comply with the applicable requirements in 210.52(C).
Se você tiver um espaço de bancada de 4 'ou menos, precisará apenas de um receptáculo estrategicamente colocado. Um espaço de bancada entre 4'1 "a 8 ', você precisará de dois receptáculos. 8'1" a 12' exigiria três receptáculos, 12'1 "a 16 'precisa de quatro, e assim por diante.