Multi family dwellings

Status
Not open for further replies.
B

Bonillanelson

Member
Location
Dallas
Occupation
City of Dallas Electrical Inspector
Hi Im new to this so please be patient if I make a mistake.
I have a service rated 1200 amps Meter bank, no main for a multi family dwelling, no main just 6 service disconnects to turn power for the entire building.
Back in 2016 I bought the mike holt library and on tap conductor he said the only fee can be tap, NOT
Service Wires.
so if you have the meter bank with six disconnect and the electrical contractor is tapping from the meter bank to all six services breaker which it’s all built in together than what protect the Srevive wire from overload.

Im an electrical inspector
 
The designer :)
It is, to some degree, the flaw in such a system. The original design determined the load and the conductors were sized accordingly.
It's up to anyone altering the system to assure there are no overloads.
 
Take a look at 230.90 (A) exception 3.

What protects the service conductors in the case you mentioned is the extremely conservative nature of load calculations. That is one of the reasons why if you add loads you are required to redo the calculations.
 
Thanks to everyone that commen, I really like the feed back.
how do I upload pictures to the forums?
 
First, most pictures are too large in file size to attach, and you will need to resize.
At the bottom left is a button called attach files, with that browse to the file location.
what I find easier is to snip the picture, copy and insert right into the message
 
Bonillanelson said:
Hi Im new to this so please be patient if I make a mistake.
I have a service rated 1200 amps Meter bank, no main for a multi family dwelling, no main just 6 service disconnects to turn power for the entire building.
Back in 2016 I bought the mike holt library and on tap conductor he said the only fee can be tap, NOT
Service Wires.
so if you have the meter bank with six disconnect and the electrical contractor is tapping from the meter bank to all six services breaker which it’s all built in together than what protect the Srevive wire from overload.

Im an electrical inspector
Click to expand...
Normally a meter bank is factory wired from meter to the disconnect either by wire or bus bars. These are not considered "Taps" like you might be thinking but part of the listed product, but now if the contractor is altering or adding to the factory supplied setup, that is normally not allowed and would invalidate the product listing
Now if this is not a case of a meter bank but a seperate meter with seperate disconnects it would be no different whether 2 disconnect or 6 you would have some sort of tap from the meter to the disconnects. This is allowed per 230.33, 230.46, and protection of the service conductors is by same means as any other between the meter and the disconnect. Protection from fault from user side via the breaker/disconnect. Or from POCO's side via their breaker at the xfer.
Never thought about it but it also might explain the seeming waaaay undersized POCO conductors compared to the sevice conductors that we install. If a fault was to occur between the first disconnect and service POCO connection the undersized wire would almost act like a fuse. Not sure if truly intended that way or if a POCO would ever admit to that function. I don't know. But how much fault current can (what looks to be a #1) POCO wire carry vs the 4/O SE that the electrician might install for a 200A service. It would definitely fail (like a fuse) before the much larger SE.
 
Status
Not open for further replies.
Top