Sadly, city & county building inspectors do not have the time, training or proper equipment to test for this and they often falsely certify that BackUp Generator installations meet NEC code requirements.
A fire insurance inspector can look for reasons why his company could deny, reduce payment or cancel future coverage for a fire damage claim if he can trace it back to a documentable code violation. Check with your insurance agent, broker or carrier for clarification.
My client, in Mill Valley CA, had a backup generator installed : I inspected it as part of my whole house EMF Safety Assessment.
Net currents of up to 12 amps were measured on circuit conduits & 2.4 Amps on the EGC (equipment grounding conductors). This also create 14 mG magnetic fields in the shop near this equipment. NEC Code compliant installations will have no net currents on conduits and No current on EGCs (equipment grounding conductors) and therefore little or no magnetic fields.
This is near carbon copy of the NEC errors I found on another backup generator installation in Marin Country CA in May of 2015. To his credit, the installing contractor came back on that installation, and corrected wiring to code so that the net currents and related magnetic fields ceased. My client hopes he will do the same on this installation.
After sharing my measurement findings, photos and videos of the backup generator transfer switches and related connection to the service panel with several Electrical Engineers and senior troubleshooting electricians I suggested, to my client, the following possibilities as a root cause of the measured net currents.
1) The installing electrician reasoned that since they were using two pole transfer switches, only the two hot wires had to go over and back, so he left the neutrals out of the conduits. This is what they did with the stage lighting I worked on. NEC 300.3(B)(1) (This is analogous to using 2 conductor cable for wiring 3-way switches, where there is no neutral run along with the travelers.)
2) He ran A phases out and back in one conduit and B phases out and back in the other. NEC 300.3(B)(1)
3) He ran both neutrals over and back to the transfer switches in the same conduit. NEC 300.3(B)(1)
Suggested Solution: have the installer return and check to see if all his connections meet code: fix and repair as required to stop net currents as measured by a flexible amp clamp. NEC Code compliant installations will have no net currents on conduits.
Related NEC codes
(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors
shall be contained within the same raceway, auxiliary gutter, cable tray, cable bus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(l) through (B)(4).
250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with250.24(A)(l) through (A)(5).
(5) Load-Side Grounding Connections. A grounding connection shall not be made to any grounded conductor on the load side of the service disconnecting means except as otherwise permitted in tris article.'(5) Load-Side Grounding Connections. A grounding
connection shall not be made to any grounded conductor on the load side of the service disconnecting means except as otherwise permitted in this article.’
250.142 Use of Grounded Circuit Conductor for Grounding Equipment.
(B) Load-Side Equipment. Except as permitted in 250.30(A)(l) and 250.32(B), a grounded circuit conductor shall not be used for grounding non-current-carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the overcurrent devices for a separately derived system not having a main disconnecting means.
For information on detecting, measuring, tracing and fixing wire code violations and exposure to other EMFs contact:
Eric Windheim, the founder of Windheim EMF Solutions is a certified Building Biology Ecology Consultant (BBEC) and Electromagnetic Radiation Specialist (EMRS). Eric provides assessments that will detect, measure and reduce sources of EMF radiation in your home, office, or business in the Sacramento and surrounding areas. Schedule an EMF Assessment with Windheim EMF Solutions Today – We Deliver Results! Less EMF, Better Health, Live Longer.
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