Art.110-26 requires "sufficient" access around all electrical Equip. for safe operation & maintenance. It doesn't define sufficient. 110-26(a),which does have dimensions based on voltage, etc. applies to equipment requiring examination, adjustment, servicing or maintenance "while energized". I dont think a peckerhead is usually accessed while energized, unless, possibly it houses terminals where voltage readings may be taken. If this is the case, it probably should comply with table 110-26(a).