RTU and Mechanical Equipment Power in the Denver Metro
Circuits, disconnects, and roof power for rooftop units, exhaust fans, pumps, and mechanical equipment.
Mechanical power follows the nameplate. Minimum circuit ampacity and maximum overcurrent protection printed on the data plate set the conductor and the breaker, and those numbers move from model to model, so a unit swap is not automatically a reuse of the existing circuit. Each unit needs a disconnecting means within sight, and the roof needs a GFCI-protected service receptacle within twenty-five feet of the equipment so the mechanical tech has power to work with.
The roof is a hard environment for raceway. Conduit run close to a sun-exposed roof surface picks up an ambient temperature adjustment that can push conductors up a size, supports have to hold without penetrating the membrane where the roofer says no, and every penetration is coordinated with the roofing contractor before it is cut. Liquidtight whips, weatherproof enclosures, and corrosion-appropriate hardware are the difference between a clean install and a service call a few winters later. This scope ends at power: control wiring stays with the mechanical contractor.
What electrical work is needed to replace a rooftop unit?
Check the new unit's nameplate against the existing circuit first. Voltage, phase, minimum circuit ampacity, and maximum overcurrent protection all have to match what is installed, or the conductors, breaker, and disconnect get changed with the unit. The whip, the disconnect condition, and the roof receptacle get verified at the same time.
Does a rooftop unit need both a disconnect and a receptacle?
Yes. The unit needs a disconnecting means within sight of it so a technician can lock it out, and the roof needs a separate GFCI-protected service receptacle within twenty-five feet of the equipment. The receptacle is for servicing and is not fed from the unit's own circuit.
Why do rooftop circuits sometimes need larger conductors than the same load indoors?
Because a black roof in full sun is hotter than the air around it, and conduit sitting close to that surface takes an ambient temperature adjustment that lowers conductor ampacity. Add continuous load rules and a long horizontal run, and the calculated size often lands above what an indoor run would need.
Based in Golden and on site across the Denver metro, from Lakewood, Wheat Ridge, and Arvada to the foothills.