# UPS maintenance bypass Canonical URL: https://eloragrid.ai/symbols/ups-maintenance-bypass Publisher: Elora Grid Updated: 2026-10-28 Lookup label: MBP Drawing use: SLD Reference families: IEC, IEEE / ANSI An arrangement of interlocked switches that routes the load around a UPS so the UPS can be isolated for work. ## In plain English ### What does UPS maintenance bypass mean? A UPS maintenance bypass is a set of switches, usually input, output and bypass, that lets the load be connected directly to the bypass supply while the UPS is fully isolated. It is normally external to the UPS cabinet so that the UPS itself can be removed without disturbing the load wiring. ### A simple example Single-line diagrams show the UPS between an input switch and an output switch, with a bypass switch connecting the input supply directly to the output busbar. Key interlocks or a make-before-break sequence prevent the UPS inverter from being paralleled with an unsynchronised bypass. ### What the drawings help you do The symbol does not tell you the sequence of operation or whether the UPS static bypass must be engaged first. Those steps are critical and must be written on the operating label or switching instruction. ### This particular reference An arrangement of interlocked switches that routes the load around a UPS so the UPS can be isolated for work. A maintenance bypass is external switching around the whole UPS; the static bypass is an internal electronic path. ### Terms - Signal: Electrical information passed between devices, rather than necessarily the main power supply. - Rating: A value stating the conditions for which equipment is specified. - Schematic: A drawing showing function and connections rather than physical appearance. Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram. - [DC UPS, AC UPS and capacitor buffer modules](https://www.phoenixcontact.com/en-gb/products/uninterruptible-power-supplies-ups) - [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) ## What it represents A UPS maintenance bypass is a set of switches, usually input, output and bypass, that lets the load be connected directly to the bypass supply while the UPS is fully isolated. It is normally external to the UPS cabinet so that the UPS itself can be removed without disturbing the load wiring. Single-line diagrams show the UPS between an input switch and an output switch, with a bypass switch connecting the input supply directly to the output busbar. Key interlocks or a make-before-break sequence prevent the UPS inverter from being paralleled with an unsynchronised bypass. The symbol does not tell you the sequence of operation or whether the UPS static bypass must be engaged first. Those steps are critical and must be written on the operating label or switching instruction. ## How to read it - Identify the three switches and their interlock. - The bypass source may differ from the UPS rectifier source. ## Information to show or reference - State ratings of each switch. - Show interlocks. - Reference operating sequence. ## Important distinction A maintenance bypass is external switching around the whole UPS; the static bypass is an internal electronic path. ## Facts - Switches: Input, output and bypass - Location: Usually external to the UPS - Interlock: Key or sequenced - Preview: Independent educational illustration; consult the applicable standard and project legend for the exact graphic ## Public references - [DC UPS, AC UPS and capacitor buffer modules](https://www.phoenixcontact.com/en-gb/products/uninterruptible-power-supplies-ups) — Phoenix Contact. Public UPS function context. - [IEC graphical symbols for diagrams](https://tc3.iec.ch/tc-activity/graphical-symbols-for-diagrams/) — IEC. IEC graphical symbol context for switches. ## Graphic scope Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.