american electricians’’ handbook, 17th edition

Frederic P. Hartwell, is a retired working electrician and president of Hartwell Electrical Services, Inc. He is certified by the International Electrical Inspectors as a Certified Master Electrical Inspector. Mr. Hartwell is the senior member of NEC CMP 9 and is the principal author of the McGraw-Hill National Electrical Code Handbook, now in its 27th edition.