- Location
- Illinois
- Occupation
- retired electrician
How does Article 450 apply...the workspace rule is in Article 110
transformer clearances
- Thread starter Dano2
- Start date
Elect117
Senior Member
- Location
- California
- Occupation
- Engineer E.E. P.E.
As Don said, this question is still lacking in details.
Voltage to ground matters.
Concrete wall is considered condition 2 for table 110.26(A)(1).
So, in 90% of circumstances you are going to need to be 3'-6". Since 150V to ground does not cover many of the typically times you would install a transformer.
This is all, of course, neglecting the sections for over 1000V.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
If the equipment is not installed with adequate working clearance then it cannot be maintained while energized, per most maintenance programs per NFPA 70E.
Isn't this a chicken or the egg issue?
Isn't this a chicken or the egg issue?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
A section in the transformer article that states that the working space in Article 110 applies to transformers. Obviously the wording is needed based on the varying opinions on this thread.
Yeah exactly when I questioned the the new no energized work over 300V safety policy they told me that the one thing every electrical incident in the last 50 years had in common was open energized 480/277 or higher voltage equipment, including a outside contractor doing an IR scan unfortunately so reducing when these things can be opened while energized is a new management priority, and that is difficult for me to get used to.
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Just like the 2023 NEC change to 440.14 on disconnecting means for applicable HVAC equipment: " Disconnecting means shall meet the working space requirements of 110.26(A)."
A question on IR surveys: as I understand it, IR windows allow the survey to be done while energized without opening up the equipment. Would it be viable to shut down the equipment and then fairly rapidly do the survey before too much cooling has occurred? You could track the time since shutdown and tag the images taken with that time. If necessary, on a unit with an IR window or other onetime safety precautions allowing imaging to start immediately at shutdown, the cooling off process could be characterized and used as a reference to translate such delayed IR readings into inferences of the temperatures at shutdown.
Cheers, Wayne
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Exactly like that. This is such a source of confusion that the words should be written into the code. Put it in either 450 or 110. We shouldn't have to go back a look for comments to a PI to get the actual requirment.