ColoradoGuy
New member
- Location
- Colorado, USA
For utility scale solar projects, often the inverter and the transformer are mounted on a skid platform, extending 12-18" beyond the inverter or transformer, as opposed to installations on a concrete foundation. The skid is a steel platform that is about 8" tall (Channel beams and plates), and is installed in an open environment, sometimes on compacted dirt, sometimes on pilings that are at ground surface level. The skid permits the inverter and the transformer to be installed as a single unit. The inverter is typically a 2 MW or larger 1000 volt (newer versions are 1500 volt) unit, connected to a transformer with a primary voltage of 34.5 kV.
A situation came up where the inverters are actually elevated and installed on a mound of dirt due to flood plain considerations, effectively making it an 18" step between the ground level and the top of the skid platform. (For clarity, the mount extends about 1 foot out from the edge of the skid, so it is a rather steep slope installation, and a significant step to get onto the skid platform.
This raised the question of NEC working space requirements of 110.26. While there is sufficient clear space around the unit, the floor/surface in front of the inverter and the transformer consist of a skid platform adjacent to the unit, and a significant step downwards if someone takes a step back. Does this arrangement meet the intent of a clear working space, with a significant floor elevation change in the 3 foot working space definition? OSHA requirements for railings don't kick in until 30" of elevation. What am I missing?
The simple answer is to de-energize the unit prior to any work/inspection. For the transformer, that could be done with hotsticks, but standing on the dirt, not the skid platform.
While I don't see a code violation here, it is uncomfortable. Am considering extending the mounding around the skid at least 2 feet, to permit the step up on the skid platform to be a consistent 8".
Would appreciate any insights on this.
A situation came up where the inverters are actually elevated and installed on a mound of dirt due to flood plain considerations, effectively making it an 18" step between the ground level and the top of the skid platform. (For clarity, the mount extends about 1 foot out from the edge of the skid, so it is a rather steep slope installation, and a significant step to get onto the skid platform.
This raised the question of NEC working space requirements of 110.26. While there is sufficient clear space around the unit, the floor/surface in front of the inverter and the transformer consist of a skid platform adjacent to the unit, and a significant step downwards if someone takes a step back. Does this arrangement meet the intent of a clear working space, with a significant floor elevation change in the 3 foot working space definition? OSHA requirements for railings don't kick in until 30" of elevation. What am I missing?
The simple answer is to de-energize the unit prior to any work/inspection. For the transformer, that could be done with hotsticks, but standing on the dirt, not the skid platform.
While I don't see a code violation here, it is uncomfortable. Am considering extending the mounding around the skid at least 2 feet, to permit the step up on the skid platform to be a consistent 8".
Would appreciate any insights on this.