North Carolina Department of Insurance Office of State Fire Marshal Risk Management State Electrical Division 2017 State Electrical Code 250.53 - Grounding Electrodes For Single Family Dwellings

Notice: The following illustrations are approved by the State Electrical Division of the North Carolina Department of Insurance, Office of State Fire Marshal. These illustrations are intended to demonstrate but not supersede the official written interpretations found at the following web address: http://www.ncdoi.com/OSFM/State_Electrical_Division//Default.aspx?field1=State_Electrical_Code_and_Interpretations Joseph Starling Chief State Electrical Engineer & Inspector Illustrated by: Danny Thomas State Electrical Inspector

Only one? Or two? Date: June 12, 2018 2017 Electrical Code Acme Meter 1 2 3 4 5 Subject: Grounding Electrodes for Single Family Dwellings Section 210.53(A)(2) and (D)(2) Question 1: If only ground rods are used as an electrode system for a single family dwelling, are two required? Only one? Or two?

250.53(A)(3) requires rods to be located a minimum of 6 feet apart Date: June 12, 2018 2017 Electrical Code Subject: Grounding Electrodes for Single Family Dwellings Acme Meter 1 2 3 4 5 Section 210.53(A)(2) and (D)(2) 250.53(A)(3) requires rods to be located a minimum of 6 feet apart (If the GEC is not continuous then 2 clamps may be required) If more than 25 ohms then rod is required to be supplemented 25 ohms or less only one rod required 250.53(A)(2) Exception However, the installer is required to assure this system meets this requirement and submit proof that is acceptable to the local electrical inspector Minimum 6 feet apart

Subject: Grounding Electrodes for Single Family Dwellings Date: June 12, 2018 2017 Electrical Code Metal Water Pipe Subject: Grounding Electrodes for Single Family Dwellings Section 210.53(A)(2) and (D)(2) Question 2: If a metal underground water pipe is used as part of an electrode system and is supplemented with a ground rod, is another grounding electrode required to supplement the ground rod?

Date: June 12, 2018 2017 Electrical Code Subject: Grounding Electrodes for Single Family Dwellings Section 210.53(A)(2) and (D)(2) Answer 2: No. The requirement of section 250.53(D)(2) requires one supplement electrode of a type chosen from sections 250.52(A)(2) – (A)(8), in which a rod is listed in section 250.52(A)(5). Both the water pipe and the rod must comply with the installation requirements of section 250.53(A). Because the water pipe and the rod make two electrodes, each supplement the other, thus 250.53(A)(2) is satisfied.

Connection must be made within first 5 feet 250.68(C)(1) METAL WATER PIPE Connection must be made within first 5 feet 250.68(C)(1) (Unless permitted otherwise by exception) Only one rod required as supplement for metal water pipe 250.53(D)(2) METAL WATER PIPE ELECTRODE Permitted if 10 feet or more in direct contact with the earth 250.52(A)(1)