Section 122. Contracts for lighting

All  municipal  lighting  shall  be
  supplied pursuant to contract therefor, awarded by the board of contract
  and supply as herein provided. Such contract shall cover and include the
  lighting and supplying of the lamps and the oil, gas, electric  current,
  the  cleaning,  repair  and  renewal  of the lamps and all the materials
  required in the use and care thereof. No bid or proposal  for  any  such
  contract  shall  be  received, nor contract awarded therefor, unless the
  bidder shall, prior to the making  of  such  bid  or  proposal,  have  a
  franchise  under  the  authority  of  which the proposed contract can be
  performed.  No contract shall be advertised for or entered  into  for  a
  period  exceeding  five  years. Each bidder shall be required to furnish
  with each bid or proposal a certified check, payable to the order of the
  city treasurer, in such sum as the board of contract  and  supply  shall
  prescribe,  but  not  less  than ten thousand dollars. Such sum shall be
  forfeited to and become the absolute property of the city  in  case  the
  bidder  depositing  the same shall be awarded the contract and shall not
  execute the same and furnish a bond for the faithful performance of such
  contract, in the penal sum of not  less  than  fifty  thousand  dollars,
  within  thirty  days  after  the  award of such contract. Such certified
  check shall be returned to the bidder if the contract be not awarded  to
  him,  or,  if awarded, he shall have executed and furnished the contract
  and required bond.
    The common council may  by  ordinance  establish  a  special  lighting
  district or districts for the purpose of ornamental street lighting, and
  from  time  to  time may alter or extend the same. The board of contract
  and supply may contract for lighting any such district or  districts  so
  established or extended, as such board may deem proper or expedient. Any
  contract  so  entered into shall be in conformity with the provisions of
  this section, except  that  the  bond  to  be  given  for  the  faithful
  performance  of  the  contract  shall  be in such amount as the board of
  contract and supply shall determine. The amount of any contract that may
  be entered into for such special lighting pursuant to the provisions  of
  this  section,  shall be assessed ratably upon the real property in such
  lighting district or districts in such manner as shall be provided by an
  ordinance duly adopted by the common council and approved by  the  board
  of  estimate  and  apportionment;  and such assessments shall be levied,
  enforced and collected upon and between the  taxable  property  in  said
  city  and district or districts respectively, in the same manner, by the
  same proceedings, at the same time, under the same penalties and by  the
  same  officers  as  the city taxes, charges or expenses of said city are
  now levied,  enforced  and  collected.  The  common  council  shall,  by
  ordinance,   approved  by  the  board  of  estimate  and  apportionment,
  apportion the expense that shall be borne by  the  taxable  property  in
  such  special lighting district or districts, and the city at large; but
  in no event shall the taxable property  in  any  such  special  lighting
  district or districts be charged with less than fifty per centum of such
  charges or expenses.