In most electrical systems, the color coding of wires does not directly indicate positive or negative polarity. The color coding of wires is primarily used to identify different functions or purposes of the wires within the electrical system. Therefore, it is not accurate to say that the blue wire is universally negative or positive.
The specific polarity of a wire, whether positive or negative, depends on the application and the circuit it is connected to. In DC (direct current) systems, which have a positive and negative polarity, the positive wire is often colored red, while the negative wire is typically colored black. However, this color coding convention is not universally followed, and different colors can be used in different contexts or regions.
It's important to note that in AC (alternating current) power systems, which are commonly used for residential and commercial electrical supply, there is no concept of positive and negative polarity. Instead, the electrical system consists of hot/live wires (which carry current) and neutral wires (which provide a return path). The color coding for these wires can vary, but in some cases, the color blue is used to identify a neutral wire.
It is crucial to consult the relevant electrical codes, regulations, or guidelines specific to your location or project to determine the correct identification and use of wires. Additionally, seeking the assistance of a licensed electrician or qualified professional is highly recommended when dealing with electrical wiring to ensure safety and adherence to proper wiring practices.