# Number of Turns vs. Wire Gauge (BLDC Motor)

#### George-M

Summary
For the same mass of copper wire, would more turns or greater thickness create a stronger magnetic field from a coil?
Summary: For the same mass of copper wire, would more turns or greater thickness create a stronger magnetic field from a coil?

So I am attempting to make a brush less DC motor, and I am wondering whether the coils would create a greater magnetic force if there are more turns or if the wire is thicker. If the copper wire is thicker, there will have to be fewer turns. If the copper wire is thinner, there will be more turns. I do believe that wire of a greater thickness has less resistance. Imagine I have two coils of copper wire with the same mass of identical copper wire; one of greater thickness but fewer turns, and the other of less thickness but more turns. My question is: which would create the strongest magnetic force? (Extended distance/ range of magnetic field is not necessary, because the rotor will be extremely close to the coils anyway). Please pardon my lack of technical terminology.

#### phinds

Gold Member
the magnetic field has nothing to do with the size of the wire but everything to do with the number of turns. More turns, greater field intensity.

#### anorlunda

Mentor
Gold Member
Thicker wire permits higher currents. So for the same current thinner wire and more turns allows a more powerful field.

The limit is thermal; how much heat can you dissipate from the coils at a reasonable temperature. The thermal load is produced by $I^2R$ losses. Thinner wires have higher R per foot and more feet if you increase the number of turns.

A BLDC motor is designed to mate with a BLDC controller. You have to consider how much current the controller can provide.

As in most designs, everything interacts with everything else and there are many tradeoffs.

https://www.edn.com/design/sensors/4406682/Brushless-DC-Motors---Part-I--Construction-and-Operating-Principles

#### George-M

Thank you both ever so much. I am going to use thinner wire because, I have a design that should keep temperatures low as is.

"Number of Turns vs. Wire Gauge (BLDC Motor)"

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