which is better, stranded or solid ground wire for bonding and grounded applications?
Electrically, they’re about equal; if your application involves high frequency AC, stranded is slightly more effective, because of the skin effect, otherwise, there’s no electrical reason to use one over the other. Mechanically, stranded is more flexible and it fares better in applications where there is a lot of vibration and flexing of the wire. In that sense, stranded is probably better but the actual answer is going to be dependent upon your particular application.
the grounding standards we use for communications sites (Motorola R56) allow for either stranded or solid wire. Stranded is easier to work with, and is obvious if you’re grounding something that moves such as a gate or door. Solid wire is recommended for underground/buried applications as it does not deteriorate as rapidly as stranded.
Note that the advantage is very slight for typical stranded wire. The increase in effective (high frequency) surface area is only due to the increase in the perimeter of the bundle, not the the surface area of the individual strands. By spacing the strands with insulating material (litz wire, or “birdcage” antenna elements) this perimeter can be greatly extended, resulting in large reduction in AC resistance.
I just want to second the recommendation that you not use solid if there is vibration present. There is a reason cars are not wired with solid wires.
Kevbo is right, though I might add that litz wire is also special in having each conductor spend equal amounts of time at different radii relative to all the other conductors, which further minimizes the overall resistance.
You know how thin dielectrics give higher capacitance, so if you make two plates arbitrarily close you get arbitrarily high capacitance? Well, the same thing happens with the circumference of a wire and high inductance. For this reason you get much better RF grounding or bonding if you use tubing or strips of foil or flat braids or multiple parallel wires, because their group circumference is much bigger.
It depends. Solid wire (thicker the better) carries the most amperage. Good for protecting an antenna from lightning strikes. For noisy dissipation (high frequency, low amperage), stranded wire is best. Good for a stereo system.
Stereo systems do not carry high-frequency signals.
Noisy dissipation?
In straight-forward residential and commercial wiring, either is usually permitted. The only real problem with smaller stranded wire is that it will crush under a properly tightened screw or lug, and some strands may not be captured under the connector, which can lessen the ampacity of the wire.
Stranded = flexible, solid = does not move.
Note the wires in appliance and extension cords are typically stranded.
And when flexible electrical conduit is used, many times stranded wire will also be used. With ridged conduit, solid wire.
Underlying all this is the fact that stranded wire is much more expensive than solid wire (about 250% of the price of solid wire).
Thus for normal home/business electrical wiring, solid is what is used most often.
And for the same gauge, stranded wire has slightly higher resistance per unit length.
OK, I have a followup question. Say you have a corpse and you are trying to re-animate it using a jolt of electricity, is stranded or solid wire better for avoiding the risk of creating a zombie?
It’s a lot easier to use stranded wire to tie the zombie up because it is more flexible.
And has a slightly larger diameter.
And has three more letters.
I’m pretty sure the cross-sectional diameter of 12 AWG solid wire is the same as the cross-sectional diameter of 12 AWG stranded wire.
If the cross-sectional diameter of 12 AWG solid wire is exactly the same as the cross-sectional diameter of 12 AWG stranded wire, then the former would have slightly greater resistance per unit length (as measured by a tape measure).
So far as cross section, I seem to recall reading something about electricity traveling on the outside surface of a wire? Or that may have been just with automotive spark plug wires?
But that may be a factor in the design of stranded vs solid? (I don’t know.)
It depends on the frequency and a few other things. See skin effect and proximity effect.