Multiple Taps

Status
Not open for further replies.
J

john37

Senior Member
Location
Riverside, California
I have a question regarding multiple taps. Currently there is an existing 480-208/120V, 3 phase transformer that feeds an existing panel. Evidentially later on someone came in and tapped the panel bus to add another panel. We need to relocate the second panel that was tapped off the bus on the first panel but now the plans examiner made a comment that "Verify the transformer secondary conductor feeding Panel B, multiple taps from a single transformer secondary must originate at the transformer." I couldn't find in the NEC where it states this. Could someone please direct me to which Article that states this? Thanks.
 
I attached a diagram to what I am referring to. The plan examiner is referring to where the existing tap on Panel "HA". He's saying it needs to be tapped at the transformer. I'm trying to find the article that states that. Thanks.
 
I can't find anything in 450 forbidding this either and it appears from your drawing that what you want to do is allowed by 230.82. Maybe the issue is the length of the tap conductors. Ask him for a code reference.
 
The installation is a tap of a tap and prohibited by 240.21.
240.21 ...Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.
Click to expand...
 
I talked to the plan examiner and he referred to Article 240.21(C)(2)(2)
which states:
"240.21(C) Transformer secondary conductors. A set of conductors feeding a single load, or each set of conductors feeding seperate loads, shall be permitted to be connected to a transformer secondary, without overcurrent protection as the secondary, as specified in 240.21(C)(1) through (C)(6).....
240.21(C)(2)Transformer secondary conductors not over 10ft long. Where the length of secondary conductor does not exceed 10ft and complies with all of the following:
240.21(C)(2)(2) The secondary conductors do not extend beyond the switchboard, panelboard, disconnecting means, or control devices they supply."
The tap is under 10ft. This is an existing installation the way I show it on my one line diagram. They are making us correct it since we are relocating the panel tapping off the original panel that was fed from the transformer.
 
John
As Don has pointed out, your drawing shows a tap of a tap, which is not permitted.
Remember that the conductors that are insalled from the secondary of a transformer are considered "tap" conductors.

If you want to, you can install a second set of conductors from the secondary of the transformer to the second load.
 
Status
Not open for further replies.
Top