Mike Dolt Enterprises
Mike Dolt Enterprises
User: jaylectricity, Location: Massachusetts
Asked on: Friday, April 22, 2011 at 11:59 pm EDT
Answered on: Tuesday, May 14, 2024 at 4:33 am EDT
Question: I saw it yesterday and sorry I don't have a picture for you but tell me what you think of this:A 4" square metal box near a circuit panel. A pair of metal flex raceways with 3-4 ungrounded conductors in one, and two neutrals in the other. Both use a duplex MC connector to enter both the panel and the 4" square box. This is how the 3-4 branch circuits are fed from the panel.What are the issues here? I recall something from school about having the hot pass through one metal circle while the neutral passes through a different one. But that was a decade ago and I haven't run into any similar situation since then.Is it EMFs or harmonics or something like that?
Issues with the Electrical Installation
Multiple Conductors in Conduit
According to the National Electrical Code (NEC), multiple ungrounded conductors in a single conduit are generally not allowed unless they are bundled within a multi-conductor cable with an overall jacket.
Duplex MC Connectors
Duplex MC connectors are designed to connect two insulated wires, not bundles of ungrounded conductors. Using them to connect multiple conductors violates the NEC.
Separate Hot and Neutral Conduit Penetrations
As you mentioned, the NEC requires separate conduit penetrations for hot and neutral conductors to minimize electromagnetic interference (EMI). In this case, both the hot and neutral conductors are passing through the same conduit and connectors.
Consequences of These Issues
EMI
The proximity of the hot and neutral conductors in the conduit can create EMI, which can interfere with other electrical and electronic devices nearby.
Neutral-Grounding Effects
The shared neutral path between the branch circuits can result in neutral-grounding effects, where current imbalances on one circuit can affect the voltage and current levels on the other circuits.
Overheating
The improper use of duplex MC connectors and the excessive number of conductors in the conduit can increase the risk of overheating and electrical fires.
Code Compliance
The installation violates multiple NEC requirements, which could lead to safety hazards and potential electrical problems.
Recommended Corrective Actions: Remove the ungrounded conductors from the metal flex conduits and install them in separate, properly sized conduits. Use multi-conductor cable with an overall jacket for the branch circuits. Use single-pole MC connectors instead of duplex MC connectors. Install separate conduit penetrations for the hot and neutral conductors. Inspect the installation for any other potential code violations or safety hazards. Flag for review