Ah, I had thought a MWBC was single phase, or anti-phase. Obviously not so for 277V 3ph wye.sure hope so -it is done a lot
Need handle ties on single pole or multi-pole breakers as the disconnecting means to assure you disconnect all ungrounded conductors of the circuit when you operate the disconnecting means - but that rule only was put in code maybe around 15 - 20 years ago.
How does the neutral wire prevent MWBCs from operating at 240v?
- Thread starter jselesk2
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kwired
Electron manager
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- NE Nebraska
NEC definition of MWBC:
Branch Circuit, Multiwire.
A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
What you most commonly run into is single phase (usually 120/240, but can be other voltages), two ungrounded plus neutral of a three phase wye, or all three phases and neutral of a three phase wye.
gar
Senior Member
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- Ann Arbor, Michigan
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- EE
180419-0931 EDT
The concept of a neutral wire was invented by Edison.
Edison could create a practical light bulb in 1879 that could tolerate a maximum voltage around somewhat above 100 V. At the time 200 V was not feasible.
To reduce the amount of copper, cost, for distribution the neutral system was invented. This system provided a means to supply 100 V loads with less copper for a given total power transfer.
.
The concept of a neutral wire was invented by Edison.
Edison could create a practical light bulb in 1879 that could tolerate a maximum voltage around somewhat above 100 V. At the time 200 V was not feasible.
To reduce the amount of copper, cost, for distribution the neutral system was invented. This system provided a means to supply 100 V loads with less copper for a given total power transfer.
.
- Status