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In electrical engineering, a node is any region or joining point on a circuit between two circuit elements. In circuit diagrams, connections are ideal wires with zero resistance. Whether "node" refers to a single point of junction or an entire equipotential region varies by the source.[1][2]

"Node" is often used, especially in mesh analysis, to mean a principal node, which is distinct from the usage defined above. A principal node is a point in a circuit diagram where three or more connections meet.[3][4] Principal nodes are important points of consideration in applying Kirchhoff's circuit laws, because conservation of current means current can split or combine at these points.
When clarification is needed, a region connecting only two circuit elements is referred to as a simple node, where there is no branching of current, while a point connecting three or more elements is a principal node.[5] The full definition uses in this article encompasses both principal and simple nodes.
Details
editAccording to Ohm's law, V = IR, the voltage V across any two points of a node with negligible resistance R is
showing that the electric potential at every point of a node is the same.
There are some notable exceptions where the voltage difference is large enough to become significant:
- High-precision resistance measurements using a Kelvin connection
- The difference in voltage between ground and neutral, between the neutral wire and the ground in domestic AC power plugs and sockets, can be fatal. A properly installed electrical system connects them together at only one ___location, leading many people to the fatally incorrect conclusion that they are at "the same" voltage, or that the safety ground is "redundant and unnecessary"
- The Seebeck effect and the Peltier effect
- Joints involving aluminium wire
Dots used to mark nodes on a circuit diagram are sometimes referred to as meatballs.[6]
References
edit- ^ Smith, Ralph J. (1966), Circuits, Devices and Systems, Chapter 2, John Wiley & Sons, Library of Congress Catalog Card No.: 66-17612
- ^ Chen, Wai-Kai, The Electrical Engineering Handbook https://nibmehub.com/opac-service/pdf/read/The%20electrical%20engineering%20handbook%20by%20Wai%20Kai%20Chen.pdf, pg 5, Elsevier (2004), "A node is a junction point where the terminals of two or more elements are joined."
- ^ "Circuit Nodes". Technology UK. Retrieved 2025-06-11.
- ^ "Analysing Electric Networks". mathonweb.com. Retrieved 2025-06-11.
- ^ "How Many Elements are Joined to a Principal Node?". testbook.com. Retrieved 2025-06-11.
- ^ Mansfield, Michael; O'Sullivan, Colm (2010), Understanding Physics (2nd edition), Chapter 14, page 359, John Wiley & Sons