Is it safe to live across the street from a edison substation ( huge wires etc surrounded by a block wall).?

This is a loaded question. If someone says it is dangerous they risk being sued. If they say it is safe they risk being sued as well by the party who inquires.
I will try to make an attemp to give an answer.
A few Years back it was stated by people making tests and surveys all over the world that a safe distance from power lines is 1/3 of a mile or around 1700 feet. Some of those same people who stated this information said, if you have an old radar detector I am guess x or K band, and you have it in your car and point it in the direction of the substation and it start beeping you should have your answer. Keep in mind differnt times of day different amounts of power. You may also consider if it is a misty or marine layer of a day. Some power lines utilize more power than others ( depending on usage ) and some power lines transmit on DC or Direct Current as opposed to AC or Alternating Current. I have heard that the City Los Angeles gets a fair amount of its power from the state of Washington and transmits 4 times the voltage in a DC format all the way down to Los Angeles. From what I have heard, Edison usually utilyses or has in the past uses approx 32000 - 64000 volts A/C.
I personally would not live near a Substation or Under High Power Lines that feed a city or town.
I also would not live next to a freeway, a gas station, or a busy street.

You asked if it is safe,...
These edison substations have been around for years and many people have lived close to them as well as across the street. I personally have not heard of anyone growing a 3rd arm as of yet. I havent seen or heard anything on 60 minutes, 20/20, Maury, or the news as of yet.

I think you might want to look into the possibilities of Cancer from EMF perhaps from the standpoint of doctors who may have treated any symptoms.

http://www.who.int/peh-emf/about/WhatisEMF/en/index1.html

http://www.epa.gov/radtown/power-lines.html

I sure don't believe for a minute Edison would want to cause any problems for people intentionally. Edison is doing its part to make our life easier by providing us power.
Now if you want to talk about companies who definitely do more damage and little to no good,...
Cigarette companies,... soft drink companies,... Candies, creme filled baked goods, etc,
I think it is each adults due diligence to see there surroundings, protect their family, and perhaps error on the side of safe and not live across or next to power lines, telephone cell towers or stand next to Microwaves when in use.

I hope this helps you in any decision making to where you choose to live.

Harold Sharpe
So Cal Homes Realty