Padmount Transformer Explained
A padmount transformer is a ground-mounted electric power distribution device enclosed in a secure, weatherproof cabinet. Commonly used in residential and commercial areas, it steps down high-voltage electricity to lower levels for safe local use.
What is a Padmount Transformer?
A padmount transformer is a ground-mounted utility distribution transformer, typically housed in a locked metal cabinet and situated on a small concrete pad.
✅ Used to step down high-voltage electricity to usable levels
✅ Housed in locked, weather-resistant metal enclosures on concrete pads
✅ Common in residential neighbourhoods, commercial buildings, and industrial sites
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These distribution transformers are normally located in residential subdivisions. Since all of the live contact points are enclosed in a grounded metal box, this kind of transformer can be situated in residential locations and do not need to be fenced, like transformers in utility substations.
Padmount transformers are connected to underground utility distribution lines at what is called a "service drop", to step down the primary voltage on the utility distribution line to the lower secondary voltage, which is then supplied to a utility customer. Many padmount transformers may serve a single large building, or they may serve many residences.
They are typically manufactured with power ratings ranging from around 75 to 5000 kVA and often include built-in fuses and switches.
A typical enclosure features a tank that holds the core/coil assembly of the padmount transformer, immersed in oil or a similar medium, and a wiring cabinet with high- and low-voltage wiring compartments to enclose the high- and low-voltage bushings of the transformer, respectively. To prevent unauthorized access to the core/coil assembly of the device housed within the tank of the enclosure, the most common prior art practice is to weld a cover over the top of the tank.
Other prior art tank covers are secured with carriage bolt-nut assemblies, and include some means for shielding the nuts, etc. Such shielding results in a cover that protrudes several inches past the top of the tank cover, causing water and other debris to be trapped along the edge of the cover. The wiring cabinet of a typical padmount transformer enclosure includes left and right sidewalls, as well as left and right lockable doors that swing open, exposing the high- and low-voltage wiring compartments. One of the doors swings out to the right, and the other door swings out to the left, leaving the front completely open; however, the right and left sidewalls remain fixed in place.
It is recommended that padmount transformers be located according to specific guidelines regarding exterior building walls. These guidelines are based on insurance industry-recommended practices for the outdoor location of one of these transformers. The building owner and/or the tenants' fire insurance carrier, or the local inspection authority, may restrict the proximity of the equipment to any part of the building structure. It is the Customer’s responsibility to determine the acceptability of the proposed location to those authorities outside of the Company.
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