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AC disconnect
- Thread starter newt
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ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Not that I know of. Why would you want to do that? The PV inverter belongs on the load side so that when the switch is open the blades and fuses (if present) are not energized.Is there a code section that allows pvs ac disconnect to be wired backwards, inverter ac lands on the line and not load.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Ask your installer if he wants to change fuses on a disconnect with the line connected to the load side. Have an ambulance standing by.I agree but installer doesnt Im looking for a code article to prove it.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Incidentally, according to inspectors that I have spoken with, connecting AC discos backwards is the single most common error in the installation of PV systems. The determining factor is not current direction, it's what remains energized when the switch is opened. Grid tied inverters MUST shut down when disconnected from the grid and their output MUST be connected to the load side of the disco. Connecting the disco the other way round will at the very least cause your system to fail inspection.Ask your installer if he wants to change fuses on a disconnect with the line connected to the load side. Have an ambulance standing by.
Your installer needs more education, IMO.
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SIRSPARKSALOT
Member
- Location
- Northern NJ
I had an integrator tell me the same thing years back. I informed them they were incorrect in a written letter to the PM. He pushed it to the engineer who came back with a narrative of how he wanted the disconnects terminated...which was backwards. I instructed my guys to install as per the narrative and went to the office and began the change order I knew was coming upon inspection.
I agree that this is one of the most seen violations in addition to:
non DC rated disconnects
non DC rated fuses
improper labeling
I agree that this is one of the most seen violations in addition to:
non DC rated disconnects
non DC rated fuses
improper labeling
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Tell the engineer that it's his job to install the fuses in the disco. Let him think about that for a moment.I had an integrator tell me the same thing years back. I informed them they were incorrect in a written letter to the PM. He pushed it to the engineer who came back with a narrative of how he wanted the disconnects terminated...which was backwards. I instructed my guys to install as per the narrative and went to the office and began the change order I knew was coming upon inspection.
I'm an engineer, and I understand the engineer's propensity to go to the mat over a fine point. OTOH, I also understand the necessity for an engineer to be able to instantaneously and with no ego involvement switch sides in an argument when faced with hard evidence that his stance is incorrect. Having the fuse holders in a disco remain live when the switch is opened is absolutely incorrect, and anyone with half a brain should be able to reason that out in short order. No code book needed.
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SIRSPARKSALOT
Member
- Location
- Northern NJ
Agreed.
shortcircuit2
Senior Member
- Location
- South of Bawstin
Code section 110.3(B)
electrimate
Member
- Location
- Baton Rouge, LA
690.16(B) says that if the fuses are energised a disconnecting means must be installed to turn off the power.
You gotta have a disconnect for your disconnect...
You gotta have a disconnect for your disconnect...
David B Rivera
Member
- Location
- El Paso, Texas
The DC Disconnect should cut off the source circuit to the inverter allowing you to service the fuses on the AC disconnect. Thus providing the disconnect for your disconnect.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
The DC Disconnect should cut off the source circuit to the inverter allowing you to service the fuses on the AC disconnect. Thus providing the disconnect for your disconnect.
Not at all correct. A DC disconnect will in no circumstances de-energize the line-connected parts of an AC disconnect.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
The fuses in an AC disco will be on the load side, not the line side, but of course as long as the AC disco is closed, the fuses are energized irrespective of the state of the DC disco.Not at all correct. A DC disconnect will in no circumstances de-energize the line-connected parts of an AC disconnect.
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