Electrical glossary
Plain-English definitions of 0 electrical terms you will see on quotes and inspection reports.
- 0Terms defined
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Find the word. Read the definition. Check the bid.
Understanding six or seven terms is enough to read a quote critically. Service is the utility supply and its capacity in amps. Service entrance is the equipment between the utility and your main breaker - the piece that quietly makes panel quotes expensive. Branch circuit is one protected run from a breaker out to devices.
Load calculation is the document that determines whether your service is adequate. If a contractor argues for a capacity upgrade, this is the artifact you should ask for. AFCI detects arcing, the ignition mechanism behind a large share of electrical fires; GFCI detects current leaking to ground, the mechanism behind most electrocutions.
AHJ - Authority Having Jurisdiction - is the local official whose interpretation of the adopted code governs your project. Not the contractor, not NFPA. Listed means a product has been tested and certified by a recognized testing laboratory for its intended use. Grandfathered is informal shorthand for existing work permitted to remain because it complied when installed; it is not a synonym for safe.
Three rules for every term
- Learn 'load calculation' first It is the term that converts a sales claim into a checkable document.
- Know 'AHJ' When someone says 'the code requires,' the real question is what your AHJ enforces.
- 'Grandfathered' means legal, not safe Ask whether a finding is a hazard or just a difference from current code.
A-Z electrical dictionary
Search or jump by letter. Each row is a complete definition.
Glossary terms for this industry are being written.
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