Is it better to pass a service as an argument in a constructor or pass it in each class method?

from government.powerSupply import power

Case 1: Should service object be initial zed in constructor of the class and same amont of energy be available to house at all times

class Home(object):
    def __init__(self, rooms=4, people=2, services=None):
        self._services = services or power.Service()
        self.connectionType = 2 # MeghaWatts
        self.roomLights = {1:False, 2:False: 3: False, 4: False}

    def turnLightsOn(self, room=None, all=False):
        voltage = self._services.voltage()
        if all:
            for light, _ in self.roomLights.iteritems():
                    self.roomLights[light] = True
            return True
        else:
            if room:
                    self.roomLights[room]
                    return True

or

Case 2 it should be done like this that function being called outside should have option to pass in services so different amount of power can be given to room whose light being turned on.

class Home(object):
    def __init__(self, rooms=4, people=2, services=None):
        self._services = services or power.Service()
        self.connectionType = 2 # MeghaWatts
        self.roomLights = {1:False, 2:False: 3: False, 4: False}

    def turnLightsOn(self, room=None, all=False, services=None):
        # in this case service can be passed from outside when call to         
        # turnLights on is made, and service can have different voltage input 
        self._services = services or self._services
        voltage = self._services.voltage()
        if all:
            for light, _ in self.roomLights.iteritems():
                    self.roomLights[light] = True
            return True
        else:
            if room:
                    self.roomLights[room]
                    return True

today, I was working on updating Unittest at office and found it convenient to do the Case 2. Since in my case service can contain different amount of power voltage as well as more than one service i.e a bath room may have power service or water supply service !!