Toros
Senior Member
- Location
- Tujunga, CA
See Attached Please
What is wrong with my V.D calc?
- Thread starter Toros
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kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
Curious? Why are you doing a VD calc for a 20ft circuit, or even 90 ft? :blink:
When you get to 200ft, I'll start to think about VD.
What do you think is wrong with the calc?
When you get to 200ft, I'll start to think about VD.
What do you think is wrong with the calc?
drktmplr12
Senior Member
- Location
- South Florida
- Occupation
- Electrical Engineer
All of your calculations are hidden in your spreadsheet...which means no one can really comment on what's wrong with it. Is the result not what you are expecting? As kingpb asked, what do you think is wrong?
To answer kingpb's question... In some municipalities, the building department and plan reviewers require you to show voltage drop calculation results. Especially for 120V motors/actuators. You can get to 3% pretty quickly running #12's that are drawing 2-3 amps.
I don't tend to show them for the feed between transformers and load panels since they are typically very close to one another and runs are ~5-10 ft and it seems the plan reviewers we work with are okay with that. However, I would definitely show it for a 113A, 90 ft run. Although the wire size is much larger than the load it appears. So V.D. should, in theory, not be an issue. It still should be documented so the engineer can demonstrate due diligence. Just my opinion.
To answer kingpb's question... In some municipalities, the building department and plan reviewers require you to show voltage drop calculation results. Especially for 120V motors/actuators. You can get to 3% pretty quickly running #12's that are drawing 2-3 amps.
I don't tend to show them for the feed between transformers and load panels since they are typically very close to one another and runs are ~5-10 ft and it seems the plan reviewers we work with are okay with that. However, I would definitely show it for a 113A, 90 ft run. Although the wire size is much larger than the load it appears. So V.D. should, in theory, not be an issue. It still should be documented so the engineer can demonstrate due diligence. Just my opinion.
As a side note, we recently had a discussion on NEC Vd recommendations for feeders. One of the items noted is that it does not limit feeders to 2%. Many interpret the recommended limit of 5% total for feeders and branch circuits to mean 2% for feeders. That is not the case. The recommended limit is 3% for either feeders or branch circuits, but not exceeding 5% total.
I realize your feeder VD drop calculation header states PER 2013 NON-RESIDENTIAL ENERGY COMMISSION ,COMPLIANCE MANUAL, so the preceding may not apply.
I realize your feeder VD drop calculation header states PER 2013 NON-RESIDENTIAL ENERGY COMMISSION ,COMPLIANCE MANUAL, so the preceding may not apply.
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