Transformer needs disconnects on both sides according to 450.14?

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ryangittens

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Location
usa
When we have a transformer connected as shown, I know we don't need an OCPD on the inverter side according to 690.9 exception but do we need a disconnecting means on the secondary (inverter) side per 450.14? Looking at each side as the primary side it would be necessary right?

xformer disconnecting means.jpg
 

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augie47

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Location
Tennessee
Occupation
State Electrical Inspector (Retired)
IMO, there is no reason to "look at both sides as being primary", but if one does so you could still take advantage of the 450.14 wording to use the panel disconnect provided it is lockable.
I do question the possibility of a violation of 240.21(C) tap rules. Depending on the length of the conductors, you might need a disconnect with over-current device.
 

pv_n00b

Senior Member
Location
CA, USA
I could make an argument that since the inverter automatically shuts down if you open the PV AC disconnect at the POI that there is no "source" on the inverter side to disconnect. Now if you had a multimode inverter that provided backup power through the transformer with the PV AC disconnect open then you would.
 
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