Temporary Power and Generator Tie-Ins in Colorado
Temporary power is permanent-grade work for as long as it is energized, because the generator, cabling, and tie-in all have to be safe under real load.
Temporary installations cover drilling and completion phases, facility construction, planned outages, and recovery after a failure or a storm, and NEC Article 590 sets the rules for how long they may remain and what protection they need. A generator feeding a site either is or is not a separately derived system, depending on whether the neutral is switched at the transfer equipment, and that one decision determines where the neutral to ground bond is made and how the grounding electrode conductor is run. Getting it wrong produces parallel neutral current, nuisance ground fault trips, or an ungrounded system nobody intended.
Tie-ins to existing gear need a properly rated transfer means, whether that is a manual transfer switch, an automatic transfer switch, or a listed camlock connection panel, sized and protected for both the generator and the load. Field cabling is protected from traffic and equipment, connections stay out of standing water, and receptacles on temporary construction power carry GFCI protection. Work near classified areas adds a further constraint, since generators and distribution equipment stay outside the classified envelope unless they are rated for it. 10 Point Services is based in Golden, Colorado.
When is a generator a separately derived system?
A generator is separately derived when there is no direct electrical connection between its circuit conductors and the supply conductors of the other source, which in practice means the transfer switch opens the neutral along with the phases. In that case the neutral to ground bond is made at the generator and a grounding electrode conductor is run to it. If the neutral stays solidly connected through the transfer equipment, the generator is not separately derived, the bond stays at the service, and no second bond is made at the generator.
What does NEC Article 590 cover for temporary power?
Article 590 covers temporary electric power and lighting installations, including time limits for construction and remodeling use, permitted wiring methods, receptacle and GFCI requirements, lamp protection, and the requirement to remove temporary wiring when the work is finished. It relaxes some rules for temporary use, but it does not relax grounding, overcurrent protection, or suitability for the location.
Can a rental generator be connected to an existing panel without a transfer switch?
It should not be. Backfeeding a panel without a listed transfer means can energize the utility side and puts line workers and equipment at risk, and it leaves no interlock preventing two sources from being connected at once. A manual or automatic transfer switch, or an interlocked breaker arrangement suited to the equipment, gives a defined break between sources. The connection also has to be sized and protected for the generator output, not only for the load.
Based in Golden and on site across the Denver metro, from Lakewood, Wheat Ridge, and Arvada to the foothills.