Yes, what your guy did is a violation of NEC Article 300, specifically 300.3(B) and likely 300.20(A). Here's why: 300.3(B) Conductors of the Same Circuit

This section requires all circuit conductors, including the grounded conductor (neutral) and equipment grounding conductor, to be installed in the same raceway, cable, or enclosure. The reason for this is to maintain a low impedance path for fault current and to reduce inductive heating. By splitting the phases, neutral, and ground into separate raceways, you've created a high-impedance path, making it difficult for overcurrent protection devices to operate quickly in the event of a ground fault. This is extremely dangerous.

300.20(A) Induced Currents in Ferrous Metal Enclosures or Ferrous Metal Raceways

This section requires that when conductors carrying alternating current are installed in metal enclosures or raceways, arrangements shall be made to avoid heating the surrounding metal by induction. When current flows through a conductor, it creates a magnetic field. If all conductors of a circuit are not installed together, the magnetic fields created by the individual conductors can induce circulating currents in the metal raceway. These circulating currents cause the raceway to heat up, potentially leading to insulation damage, nuisance tripping of overcurrent protection devices, and even a fire hazard.

In summary, the violation is that the conductors for each circuit are not grouped together within the same raceway.What needs to be done


Correct the wiring immediately. This is a serious safety hazard.2. Rewire the system so that all phase conductors (brown, orange, yellow), the neutral conductor, and the grounding conductor for each set of 400 kcmil aluminum conductors are installed in the same conduit. This means each 4" conduit will have one set of 400kcmil conductors, the grounded (neutral) conductor, and the equipment grounding conductor.3. Consider conduit fill. With three 400 kcmil conductors, one neutral, and one ground, a 4" conduit might be too small. You need to calculate the fill percentage according to Chapter 9, Table 1 and Annex C of the NEC. The maximum allowable fill for multiple conductors is 40%. If the fill exceeds 40%, you'll need to upsize the conduit or use more conduits.4. Ensure proper termination. Confirm that all conductors are properly terminated at both the disconnect and the switchboard, following the manufacturer's instructions and using appropriate connectors for aluminum conductors.5. Re-torque all connections. Use a calibrated torque wrench to properly tighten all terminations to the manufacturer's specified torque value.6. Inspect and test. After the corrections are made, have a qualified electrician inspect the installation to ensure compliance with the NEC and perform testing to verify proper operation.

Important Notes



Authority Having Jurisdiction (AHJ)

Always consult with your local AHJ for specific interpretations and requirements in your area.

Licensed Electrician

This type of work must be performed by a qualified and licensed electrician familiar with the NEC and local regulations.*

Documentation: Document all changes and corrections made to the electrical system.This situation highlights the importance of proper training and understanding of the NEC. Cutting corners or failing to follow code requirements can have serious consequences. Flag for review