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How many NM-cables allowed in an NM-connector clamp?
Saturday, August 8, 2020
The National Electrical Code does not adress the issue of how many cables are allowed in a single connector. It only states that “where cable is used, each cable shall be secured to the cabinet…” [NEC 312.5(C)]. The number allowed is based on the UL-rating. Most NM-connectors are UL-approved for securing only one NM-cable to a panel box. But some are rated for two #14 or #12 cables, and we know of one 3/4” connector that is rated for three.
Check the box for the number approved by the manufacturer, but it’s definitely not more than three. So the example shown at the arrow above, that clamps a total of five NM-cables (one is hidden in back) is not acceptable.
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Here’s links to a collection of our other blog posts about ELECTRIC PANELS:
• What causes copper wires to turn green or black in an electric panel?
• What is the maximum number of circuit breakers allowed in an electric panel?
• When should a corroded or damaged electric panel cabinet or disconnect box be replaced?
• What is a tandem circuit breaker?
• When did arc fault circuit interrupter (AFCI) breakers first become required?
• Can an electric panel be located in a closet?
• Can an electric panel be located in a bathroom?
• Can you add circuit breakers by different manufacturers to an electric panel if they fit?
• My circuit breaker won't reset. What's wrong?
• What is a split bus electric panel?
• How do I identify a combination AFCI (CAFCI) circuit breaker?
• What does a circuit breaker with a yellow or white test button indicate?
• What are the requirements for NM-cables entering an electric panel box?
• Why is a fuse box/panel an insurance problem for homebuyers?
• Why is bundled wiring in an electric panel a defect?
• What is the difference between GFCI and AFCI circuit breakers?
• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?
• What happens when you press the "TEST" button on a circuit breaker in an electric panel?
• What is a Dual Function Circuit Interrupter (DFCI)?
• What is the difference between "grounded" and "grounding" electrical conductors?
• What does it mean when a wire is "overstripped" at a circuit breaker?
• Why is an old fuse panel dangerous?
• Who is the manufacturer of those "bad" electric panels?
• Why is the circuit breaker stuck in the middle?
• What is a double tap at a circuit breaker?
• What is the right electric wire size for a circuit breaker in an electric panel?
• What is the life expectancy of a circuit breaker?
• My circuit breaker won't reset. What's wrong?
• Why do some breakers in my electric panel have a "TEST" button on them?
• What is the right size electric panel for a house?
• What do I need to know about buying a whole house surge protector?
• What is the maximum allowed height of a circuit breaker (OCPD) above the floor?
• What is the maximum height you can mount an electric panel above the floor?
• What is the code required clearance in front of an electric panel?
• What is the main bonding jumper and where do it find it in an electric panel?
Visit our ELECTRIC PANELS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.
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