I am working in a mixed use building. First floor is retail and the next six floors are condominiums. The building wants to install 7-level 2 EV chargers. We are installing a 75KVA transformer to feed a 225A 208V panelboard, in the basement. The feed for this is a meter bank in the first floor electrical closet. Is the feeder from the meter bank to the transformer considered a feeder or service conductors? The meter bank has a non fused pull out disconnect. The next question is do we need a OCPD for the conductors that feeds the transformer? The other tenants do not have any protection for the feeders leaving the meter bank however the installation is 20 years old.
Feeder or Service conductors and do they need OCPD
- Thread starter mjc1060
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You definitely need OCP on the transformer.
If the tenant meters don't have OCP it is likely the OCP is at the tenant panels.
As long as your conductors, which would be service conductors, stay outside the building
until they enter to OCP, you should be OK but I would suggest discussing the install with your inspector.
If the tenant meters don't have OCP it is likely the OCP is at the tenant panels.
As long as your conductors, which would be service conductors, stay outside the building
until they enter to OCP, you should be OK but I would suggest discussing the install with your inspector.
As a general principle the utility has to protect their end, too, so you have some protection in those terms.
More generally a direct “fault” in this type of equipment is going to be a short circuit (damage). An overload is due to the loads of downstream devices. The overload protection generally comes from the protection created by the overcurrent protection located at the load end of the feeder/service. So it is protected just not in the same way you might be used to thinking of it. Damage to service cables and feeders is also much less likely than it is to loads and branch circuit wiring.
This is why for instance we can run wiring from the transformer secondary terminals to a panelboard. The wiring is protected from a short circuit by the primary side protection and from overload by the panelboard.
NEC supports this way of looking at things and even extends the concept to allow wire size changes in limited cases via the tap rules.
You are not “unprotected”. You just don’t have a single zone of protection driven by a single device in a tree-like arrangement that you have control over (utility may own protection).
More generally a direct “fault” in this type of equipment is going to be a short circuit (damage). An overload is due to the loads of downstream devices. The overload protection generally comes from the protection created by the overcurrent protection located at the load end of the feeder/service. So it is protected just not in the same way you might be used to thinking of it. Damage to service cables and feeders is also much less likely than it is to loads and branch circuit wiring.
This is why for instance we can run wiring from the transformer secondary terminals to a panelboard. The wiring is protected from a short circuit by the primary side protection and from overload by the panelboard.
NEC supports this way of looking at things and even extends the concept to allow wire size changes in limited cases via the tap rules.
You are not “unprotected”. You just don’t have a single zone of protection driven by a single device in a tree-like arrangement that you have control over (utility may own protection).
Thank You both g explanations
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
Can you give more detail on this meter bank? Never seen a meter bank with non fusible disconnects. Something is not right here or I am misunderstanding.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I am very unclear about what the setup is here. About the only thing I can come up with based on the description is that it is a 230.40 exception #1 install using the provisions of 230.6. But then the pull out disconnect for a meter bank is quite puzzling. 
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Great minds think alike Texie......
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