Except with the approval in writing of the board first had and obtained, no public utility shall loan any of its money or property to any other person, firm, group, association, company, trust or corporation owning, holding or controlling separately or in affiliation with others, five per cent or more of the capital stock of any such public utility or to any corporation five per cent or more of the capital stock of which is owned, held or controlled by any person, firm, group, association, trust, or corporation owning, holding or controlling separately or in affiliation, five per cent or more of the capital stock of such public utility.
N.J.S. § 48:3-7.2