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Tuesday, April 23, 2019

Question:

Can a new Packaged RTU HVAC unit with a 208-230/3 rated CSA data tage be applied to a grounded "B" phase 240 v delta service without modification to the CDA unit label?

Paul Willmus
A

Answer:

Hey Paul thanks for your question. You should ask the rooftop unit (RTU) equipment manufacturer for that answer. Equipment must be marked with the manufacturers name or description as stated in 110.21(A)(1). Factory installed internal wiring or the equipment construction usually does not need to be inspected in the field as stated in 90.7, paragraph 2. In addition to possible voltage-to-ground limitations of some internal components, overcurrent devices are generally not allowed in series with grounded conductors (B phase in your example) for NEC applications as stated in 240.22.

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