Generator Transfer Switch Equipment Bond

[Esi5]

Any thoughts on 240/120v > 3-wire vs. 4-wire to transfer switch from meter can to SE rated transfer switch.
Bonding jumper is utilized between neutral and ground bus in transfer switch.
Main panel becomes a sub- panel whereas ground bus and neutral bus are isolated.
Some say install equipment bond between transfer switch and meter can and some don't...what are your thoughts on parallel path created with this scenario.

 

[Cow]

In your example, since the transfer switch is the service disconnect, your main bonding jumper goes here. Any panels downstream would be 4 wire with neutrals and grounds separated. Meter base would get bonded to the grounded conductor, like usual, since it's on the line side of the service disconnect.

 

[kwired]

What the cow said. If this TS is your service disconnect, bond it like any other service disconnect would be and run separate grounded and grounding conductors after that point. If there is a service disconnect ahead of it, you must remove any bonding jumper that is already installed and keep incoming as well as outgoing grounded and grounding conductors separated - like you would with any other switch, panelboard, etc.

If it is rated only for service equipment, then the grounded bus is permanently bonded to the cabinet and there is no removable bonding jumper (it is intended only for use as service disconnecting means).

 

[david]

Some say install equipment bond between transfer switch and meter can and some don't...what are your thoughts on parallel path created with this scenario.

you do not need what some are calling an equipment ground between the meter can and new service disconnect (service rated transfer sw )

The neutral can be bonded to metal or earth as many times as necessary line side of the service disconnect.

If you run an additional grounded wire ( additional to the neutral) between the meter and new service disconnect you are paralleling the neutral no matter what color insulation the conductor has