I have to hook up a roftop unit It does heating and cooling.MY question is if you have a delta system does it matter which phase the high leg is hooked up to. I wanted to make sure because of the wires that come off the load side of the relay ,one of them will have the 208 line.thanks
hvac unit hook-up
- Thread starter m2oliva
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- Bremerton, Washington
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- Master Electrician
Re: hvac unit hook-up
Check the manufactures listing, if the HVAC unit is rated 240V 3 phase, it should be OK, If its not designed to use with a high leg delta then it will state that.
If the HVAC unit is rated 200V for use on 120/208 V 3 phase, it would be violation of the NEC to connect it, per
"110.4 Voltages.
Throughout this Code, the voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected."
Check the manufactures listing, if the HVAC unit is rated 240V 3 phase, it should be OK, If its not designed to use with a high leg delta then it will state that.
If the HVAC unit is rated 200V for use on 120/208 V 3 phase, it would be violation of the NEC to connect it, per
"110.4 Voltages.
Throughout this Code, the voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected."
russ
Senior Member
- Location
- Burbank IL
Re: hvac unit hook-up
430.97(B)refers to motor controllers not necessarily to the final disconnect or the roof top unit it self. In the motor controller the high phase in general, is the B phase.
The same thing is true in 408.3(E) for switchboards and panel boards.
Also the installation instructions should be checked.
430.97(B)refers to motor controllers not necessarily to the final disconnect or the roof top unit it self. In the motor controller the high phase in general, is the B phase.
The same thing is true in 408.3(E) for switchboards and panel boards.
Also the installation instructions should be checked.
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