3 wire feeder from fused service disconnect to main panel bonding

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aac

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tucson az
Hi Guy's,


I recently purchased a 1950's property where the previous owner replaced the old panel with a new one which has an isolated neutral bar and a ground bar and an egc to ground rod. The feeder for this panel is three wire and originates from a fused 100 amp disconnect which is downstream of the meter and is the main service disconnect. The neutral wire from the meter to the service disconnect is bonded to ground in the chaise above the meter via a lug connector. Should the main panel neutral and ground bars be bonded or should they be isolated? I have read a bunch of posts on the subject and they seem to suggest that: After 2008 nec code requires an egc from the main service disconnect (fused 100 amp disconnect in this case) to the panel (4 wire), and the panel should be grounded via ground rod with isolated neutral and ground bars inside the panel.
Prior to 2008 code would allow the panel to be connected via the 3 wire feeder back to the main disconnect, without separate egc, and with bonded neutral and ground bars

I'd like to know what the preferred way to update this setup would be? I don't know exactly when the panel was installed but I'd guess after 2008. My concern here is having an electrical system that conforms to code at the time it was installed. Thanks in advance for the help!

Andy
 
Are the panel and the service disconnect in the same structure? If so then the question of a 3-wire feeder between them is not relevant.
 
If the panel and the service disconnect are in/on same building there never was any allowance (for like at least past 70-80 years anyway) to use the grounded conductor for equipment grounding purposes beyond the service disconnecting means.

There was changes in 2008 that did previously allow such things for feeders to separate buildings however, since then is only allowed as an exception for existing applications that basically were compliant at the time of installation.
 
aac said:
Hi Guy's,


I recently purchased a 1950's property where the previous owner replaced the old panel with a new one which has an isolated neutral bar and a ground bar and an egc to ground rod. The feeder for this panel is three wire and originates from a fused 100 amp disconnect which is downstream of the meter and is the main service disconnect. The neutral wire from the meter to the service disconnect is bonded to ground in the chaise above the meter via a lug connector. Should the main panel neutral and ground bars be bonded or should they be isolated? I have read a bunch of posts on the subject and they seem to suggest that: After 2008 nec code requires an egc from the main service disconnect (fused 100 amp disconnect in this case) to the panel (4 wire), and the panel should be grounded via ground rod with isolated neutral and ground bars inside the panel.
Prior to 2008 code would allow the panel to be connected via the 3 wire feeder back to the main disconnect, without separate egc, and with bonded neutral and ground bars

I'd like to know what the preferred way to update this setup would be? I don't know exactly when the panel was installed but I'd guess after 2008. My concern here is having an electrical system that conforms to code at the time it was installed. Thanks in advance for the help!

Andy
Click to expand...

What is the wiring method ?
 
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