AboutRick Miell Expertise Past County electrical inspector, hold St. of Colorado Master license, will try to answer any electrical question with Code related answers.
Experience State of Colorado Master Electrician. Past County Electricial Inspector (15 years)
Question I am trying to find out the required clearances around a new 200 amp, 3 phase breaker box I am putting up in a grocery store.
Also, would like to know the correct formula for sizing 3 phase services, 240.
Thanks, Mike Cariker, Searcy AR
Answer Mike, as far as clearances are concerned, picture having a refrigerator unit standing right in front of the panel. This is the area that is required to be clear. The actual area is at least 30" wide (or the width of the panel, if it is larger than 30"). The depth in front of the panel to keep clear is 36". This is from the floor up to a hight of 6'6".
This is covered in Article 110.26 of the NEC. You can find the rules for calculations for services in Article 220 of the same book. I'm not sure what you are meaning by a formula for sizing 3-phase services, 240. Most 3-phase services will be 208Y/120v. If you do indeed have a 240v, 3-phase service, then you will have to follow the rules for the "wild" leg, which cannot be used for 120v loads.
Email me if you have any specific question at rmiell@hotmail.com
You might be better off asking your loacl inspector these questions, as they may have some other local rules to follow.
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