Generate a random, fixed length password in PHP that comply to a password policy

I need to generate a random password containing 8 characters. The password must comply to below policy --

A Password should

• contain a minimum of one (1) non-alphabetic character


• not contain more than two (2) consecutive repeated characters

I am generating my password using below function.

function random_pass() {
    $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
    srand((double)microtime()*1000000);
    $i = 0;
    $pass = '' ;
    while ($i <= 7) {
        $num = rand() % 60;
        $tmp = substr($chars, $num, 1);
        $pass = $pass . $tmp;
        $i++;
    }
    return $pass;
}

And I have written below validation function that checks if the generated password is according to password policy

function password_policy($string)
{
    // contains a minimum of one (1) non-alphabetic character
    $r1 = '/[^a-zA-Z]+/';
    // contains more than two (2) consecutive repeated characters
    $r2 = '/(.)\\1{2}/';

    if (preg_match_all($r1,$string, $o)<1) {
        return "invalid - all alphabetic";
    }
    if (!preg_match_all($r2,$string, $o)<1) {
        return "invalid - more than 2 consecutive repeated chars";
    }
    return "valid";
}

My random_pass doesn't work accurately all the time. Out 5-10 times out of 100, my password fails to comply with the password policy.

for ($j=0;$j<100;$j++) {
    $pass = random_pass();
    $validation = password_policy($pass);
    if ($validation !== 'valid') {
        print_r("$pass -- $validation\n");
    }
}

-- output --

BCZHDgKl -- invalid - all alphabetic
xfCKKKH3 -- invalid - more than 2 consecutive repeated chars
aMtcWqEx -- invalid - all alphabetic
ZtpDGeKU -- invalid - all alphabetic

How do I generate such password that will 100% comply to aforementioned policy.

Please help me out. Thanks in advance!