This is a very good question. You are wise to ask this forum as well. I am also interested in others' input. Recently, at an inspection of my client's purchases, the inspector brought up this very question. Our discussion centered around the potential health hazard. The very experienced inspector, who also has an 11 yr old daughter, said he would never live "in the shadow" of either of these.
From a business/investment decision standpoint, you need to "price in" the fact that the house is in such proximity to the high voltage towers and substation because when you go to sell the property, your buyer will likely have the same concerns and want a discount for the same reasons.
My advice is to stay away. Find another property that suits your needs and within your budget that does not have this risk. Typically, these homes are harder to sell as well.
You should have a Realtor to represent you, if you don't already. Understand that any of us can protect your interests, and it doesn't cost you a thing. The listing agent will pay my commission, but my loyalty is only to you. Feel free to contact me anytime. I would be glad to assist to make your first home purchase experience a wonderful memory (like I have many other clients).
Brent Rice, Trulia Top Recommended Broker (Pro & VIP)
The Rice Group, Inc.