I have run into a utility district that requires the neutral to be switched at the transfer switch for a residential generator install.(First for me!) I already have a 1phase transfer switch and do not want to have to spend another $1000 on a 3 phase switch. My thought was to get a NO contactor in order to switch the neutral. Does anyone see anything wrong with that and maybe a recommendation on where to find one? Thanks
Transfer switch switching neutral
- Thread starter mccayry
- Start date
- Status
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
You wouldn't have a UL listed assembly if you put pieces together.
You might also damage stuff in the home if the load is energized and the neutral opens without coordinating with the phase transfer. An open neutral can cause voltage transients / swells for 120V loads.
You might also damage stuff in the home if the load is energized and the neutral opens without coordinating with the phase transfer. An open neutral can cause voltage transients / swells for 120V loads.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Even within a single transfer switch (either automatic or manual) which switches the neutral, many include a special mechanical construction such that the neutral is not interrupted until a fraction after all ungrounded leads are opened, and the neutral is then closed to the alternate power source before any of the ungrounded conductors are closed. Note that simply using a three-phase three contact TS (without explicit provision for the neutral) will NOT give you that extra protection that a single phase three wire transfer switch could include.
The alternative, to completely prevent even a temporary open neutral condition, is to use an overlapping contact switch that parallels the two sources momentarily during the transfer (with all of the specialized protective gear that requires.)
The possibilities of the additional relay having mismatched timing characteristics or just plain failing lead to a high risk of damage to equipment.
The alternative, to completely prevent even a temporary open neutral condition, is to use an overlapping contact switch that parallels the two sources momentarily during the transfer (with all of the specialized protective gear that requires.)
The possibilities of the additional relay having mismatched timing characteristics or just plain failing lead to a high risk of damage to equipment.
guitarman21632
Member
- Location
- Federalsburg, MD USA
It is my understanding that if the neutral is opened you have to treat the generator as a separately derived system and bond accordingly
- Status