Advancement International Ltd.
595 Circlewood, Aurora, OH 44202(USA)
Phone: 330-562-8983 | FAX: 330-562-9990
International Hydraulics Inc
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Understanding Neutral Bars
Neutral bars are widely used in residential and commercial electrical service panels to terminate all those white 'neutral' or 'return' wires from the many load circuits in the building.
The black 'hot' wires are protected from overload by circuit breakers in the panel which typically sense the current in the 'hot' wire and 'trip out' if current is exceeded for too long. Current sensing is usually by an element in the circuit breaker that heats up when current is too high. As the element heats more for higher currents and gathers more heat when currents exist for extended overload periods, it mimics the wiring in the buildings circuits which would themselves heat up, causing a potential fire hazard.
The heating effect in the circuit breaker is used to trigger the spring loaded circuit breaker 'trip', turning off that circuit using a bimetallic "hair" trigger to release the spring energy holding switch contacts closed, when that certain total heating effect is reached.
The white neutral wires are not protected by a circuit breaker as it is only necessary to interrupt a circuit at one point to break current flow. That takes care of heat build up from overloads in wiring. The other safety consideration is that of voltage isolation.
As the 'hot' black wire is 110 volts (for single phase, alternating) and the white neutral wire, anchored at the panel is essentially 0 volts, the danger for shock (voltage induced current flow in the human body) is minimized.
Consequently the black 'hot' wire is the one chosen to stop both current flow and the presence of voltage in the circuit.
It is important to note that a neutral bar does still carry current even if the voltage at the location of the neutral bar is essentially zero with respect to ground. All of the current used in appliances all over the building goes through the neutral bar and back to the current source, the utility line.
All current has to come from somewhere and go somewhere like water FLOWING in a hose pipe. Whereas water PRESSURE (voltage) may be present with no current (no water flow when the tap or spray gun is shut off).
Neutral bars are simple mass wire termination devices that allow many (often white) neutral wires to be terminated in the service panel with little space and cost.
In the USA neutral bars are mainly made from tin plated aluminum (grades 6061, 6005, 6105, 6063 are common).
Brass Neutral bars are popular in many countries but conductivity of brass is about 28% that of copper while aluminum conductivity is 43% that of copper so on a cost per amp basis, aluminum is much lower cost, especially considering that aluminum weighs much less than brass or copper and costs much less per pound than brass or copper.
Tin plated neutral bars are compatible with both aluminum wiring and copper wiring. Aluminum wire today is made of a harder alloy than many years ago which enables it to compete in reliability with copper wire IF used in Dual Rated aluminum connectors such as tin plated aluminum neutral bars sold by LugsDirect.com. Generally only aluminum wire connectors are compatible with both aluminum and copper wires.
So what does it mean to say that the voltage on a neutral bar is "essentially zero"? Is the potential the same as ground (earth) then? Yes and no.
Electrical codes dictate that the neutral circuits and the ground circuits be bonded at only one point, the main entry point. This might mean in the main panel or incoming meter but only in one place and at the "source".
In a properly functioning system the ground (earth) will dissipate stray voltages that can creep into a complex wiring system. So, in essence, the neutral is forced to ground by bonding it to ground in the panel.
But beware of white wires anywhere else as there is lots of opportunities for a white wire to be hot! Remember white (neutral) wires are connected to black (hot) wires by the appliance itself and can be at 110 volts in household wiring or even 220 or 460 volts in these higher voltage circuits.
LugsDirect.com can help you with your Neutral Bar needs whether you need one or thousands!
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