You want to get an idea of the magnitude of magnetic fields produced by overhead

Question

You want to get an idea of the magnitude of magnetic fields produced by overhead power lines. You estimate that the two wires run about 27 m above the ground and about 3.4 m apart. A call to the local power company provides the information that the lines operate at 10 kV (rms) and provide a maximum of 30 MW to the local area. Estimate the maximum magnetic field you might experience walking under these power lines.

Bmax =

HINT Current will be flowing in opposite directions in the two wires. You'll experience a B-field which is the vector sum of the fields created by the two wires.
HINT: The peak current is the rms current times the square root of 2.

Can't figure this one out at all. Please include solution as well as the answer.

Explanation / Answer

I rms = 30*10^6/10^4 = 3000A

I peak = 3000root2

Bmax = 2*B*sintheta where tantheta = 3.4/2/27 and B=uI/2piR

Bmax = 2*4*pi*10^-7*3000*1.414*sintheta/(2*pi*root(1.7^2+27^2))=0.00000388T

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