Acabamos de comprar uma casa na região de Chicago e descobrimos que não há fio terra em algumas áreas recentemente religadas. Eu pensei que o código elétrico nacional requer um fio terra para novas construções e remodelas, ao contrário de depender do tubo de aço como terra. Está correto?
O conduíte (RMC, IMC ou EMT) é um caminho no solo aceito pela NEC. Portanto, se os fios estiverem em eletroduto de aço, não é necessário outro fio terra.
Se isso lhe causar preocupações, você poderá encontrar este link relatando pesquisas sobre a eficácia do canal como um alívio para elas.
O National Electrical Code permite que conduítes e tubos metálicos sejam usados como um condutor de aterramento do equipamento, desde que ele esteja instalado corretamente.
No entanto, antes de usá-lo como tal em uma instalação existente, você deve verificar se ele fornece um caminho contínuo adequado para o aterramento.
National Electrical Code 2014
Chapter 3 Wiring Methods
Article 342 Intermediate Metal Conduit: Type IMC
342.60 Grounding. IMC shall be permitted as an equipment grounding conductor.
Article 344 Rigid Metal Conduit: Type RMC
344.60 Grounding. RMC shall be permitted as an equipment grounding conductor.
Article 348 Flexible Metal Conduit: Type FMC
348.60 Grounding and Bonding. If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an equipment grounding conductor shall be installed.
Where flexibility is not required after installation, FMC shall be permitted to be used as an equipment grounding conductor when installed in accordance with 250.118(5).
Where required or installed, equipment grounding conductors shall be installed in accordance with 250.134(B).
Where required or installed, equipment bonding jumpers shall be installed in accordance with 250.102.
Article 350 Liquidtight Flexible Metal Conduit: Type LFMC
350.60 Grounding. Grounding and bonding for LFMC shall be installed in accordance with 350.60(A) and (B).
(A) If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an equipment grounding conductor shall be installed.
Where flexibility is not required after installation, LFMC shall be permitted to be used as an equipment grounding conductor when installed in accordance with 250.118(6).
Where required or installed, equipment grounding conductors shall be installed in accordance with 250.134(B).
Where required or installed, equipment bonding jumpers shall be installed in accordance with 250.102.
(B) Where Air Conditioning or Refrigerating Equipment is installed outdoors, an equipment grounding conductor per 250.118(1) shall be provided within the raceway and shall be sized per 250.122.
Article 358 Electrical Metallic Tubing: Type EMT
358.60 Grounding. Grounding and bonding EMT shall be installed in accordance with 358.60(A) and (B).
(A) EMT shall be permitted as an equipment grounding conductor
(B) Where Air Conditioning or Refrigerating Equipment is installed outdoors, an equipment grounding conductor per 250.118(1) shall be provided within the raceway and shall be sized per 250.122.
Article 360 Flexible Metallic Tubing: Type FMT
360.60 Grounding. FMT shall be permitted as an equipment grounding conductor where installed in accordance with 250.118(7).