This is kind of a quiz question that I enjoyed learning the answer to. I posted it in another forum some time ago and folks there got some fun out of it.
You have been asked to install outdoor area lighting to light the walkway between the door to a farm house and a barn; or any house and outbuilding for that matter. Here is the situation that you find at the customers premise. There is a existing conduit between the two buildings and it contains four conductors not including any equipment grounding conductor. The second building has an outside light over the door that lights the area immediately around it. This outside light is controlled by 3 way switching at the house and barn. The circuit also supplies the interior lights in the barn and a few convenience outlets. The block heater for a tractor that is used to plow snow and power take off equipment when needed is plugged into one of the outlets. The convenience receptacle outlets must remain energized at all times. The interior lighting at the barn must be switched at the barn independently of the outside lighting. There is no need to control the interior lighting from the house. The customer wants area lighting at both buildings that can be turned on or off at either door. How do you wire the circuit without repulling the conduit or violating the US NEC. In order to make the issue really clear the customer has specified that the lighting must be instant on and you already have the flood light fixtures on the truck. The fixtures are screw shell, edison based, flood heads.
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Tom
