I've Installed a transformer that on the secondary has nearly 36' of wire parallel feeding a 120v/208v panel. The engineer over seeing the job has quoted the reference in the code on a particular 10' rule. The problem I have with this rule is there are additional rules dictating that 25' is acceptable ,how does one go about determining whether the 10' or 25' apply. Either way I believe I'm going to be required to put a disconnect at the transformer.
The problem originated when we had to place a transformer into the nearest gap nearly 28' from where it was shown on the print . The engineering shown placed the transformer suspended into the air ,supported from the building steal. When we went to place this 112kva trans into the air the GC. proclaimed that the structural engineer will not allow us to suspend the trans from the steal because its to heavy. Now the electrical engineer has said we don't comply with the 10' tap rule. I feel that even though the length of the secondary taps are 26' that we may comply with the 25' tap rule. Basically I have to size the wires according to the percentage ampacity given for the conductors for the 25' rule verses the 10' rule. Next realization being is that we sized the wires according to the line diagram the electrical engineer specified, and he is probably aware that the wires may only comply with the ampacity of the 10' rule. Solutions ? Move transformer back to where it is shown on print? Build a shelf? Comments appreciated
I feel that even though the length of the secondary taps are 26' that we may comply with the 25' tap rule. Basically I have to size the wires according to the percentage ampacity given for the conductors for the 25' rule verses the 10' rule.
Sure....26' is not 25' or less.
Solution = Let the GC worry about it, and between the EE and the Structural Engineer not doing their jobs properly, let them come up with a fix.
Don't try to "save the day" yourself, you'll be rewarded with only headaches.