Home / Specifications / Dead Front and Live Front Pad Mounted Transformers
Dead Front and Live Front Pad Mounted Transformers
The difference is how the primary connects. A dead front unit uses fully insulated separable elbow connectors, so nothing energised is exposed when the cabinet is open. A live front unit uses bare bushings behind a barrier. Almost all new US commercial work specifies dead front, and many utilities will not accept live front at all.
Dead front
The primary terminates in load-break elbow connectors that are fully insulated and shielded. With the cabinet open nothing energised is exposed, and the elbows can be switched under load with a hot stick. This is what almost every US utility now requires on new work.
Live front
The primary lands on bare porcelain or polymer bushings behind a barrier inside the cabinet. It is cheaper and simpler, and it is what a great many older installations use. Opening the cabinet exposes energised parts, which is why new installations have moved away from it.
Which to specify
Dead front, unless the serving utility says otherwise in writing. It is not a meaningful price difference at commercial ratings and it is the configuration every inspector expects.
See also loop feed and radial feed.
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