Ladder safety - what is the maximum height of different ladders?

Please inform me regarding:
what is the maximum height of
1) step ladder
2) straight ladder
3) extension ladder
4) ladder used for scaffolding access

Please find attached, its more then you requested.
Thank you,

Dear friends,
On ladder safety -a very good discussion I find.
Now; can anyone give me the answer as to how the 4:1 (4V to 1H) ratio is accepted safe all over the world?
There may be a reason without which a safety man can not just say “keep the ladder that way”.
Let us start the probe !
Regards,
Kesava Pillai

Dear Sir ,
We all forum member always waiting for your kind comments.
4:1(4V to 1H) ratio creats the angle (75-1/2 deg) which enable us to utilizes the ladder's strength and gives us optimum balance when climbing.
Regards,
Abhaygirish

Dear Mr. Sayeed
Thanks for sharing good presentation on Ladder Safety... Keep on sharing...
Dear Kesava Pillai Sir
I was not knowing the answer of the question you have raised... Then I have searched in net and get the following...
"If the base is moved out further, the stress on the side rails is more severe and the wider angle may cause slippage"...
Looking forward to hear your comments... Keep on sharing your expertise with us...

Daer sir,
Here is the answer i hope its right.
Two reasons:
Matematimatical: If you do the math regarding the Side adjacent, the side tangent, and the hypotenuse, and regarding the angular momentum of the dynamic loads involved on a ladder, you realize that the 4 to 1 ratio provides the best possible load distribution at ground and tangent with the greatest stability.
Empirical: If you have a human of average height stand straight with arms extended either to each side or to the front, the triangle described by the mallous of the ankle, the shoulder hinge, and the knuckles of the finger describe a right trangle with the ratio of the side adjacent to the side tangent to be 4 to 1.
Dear abhay & Dipil,
Thanks for your inputs.
Waiting for experts commands. . .

Dear friends
It is interesting to see many "attempts" around the questions
The specific question here is “what is the maximum height of
1) step ladder
2) straight ladder
3) extension ladder
4) ladder used for scaffolding access”
We find lot of postings but none with a definite answer. Can anyone try to answer to the question please?
The ppt from Mr.Sayeed the 27th one needs correction. We have to digest the meaning of 4:1.
The max. height of step ladder and extension ladder given as 20' and 44' also requires clarification ?
Kindly check !
Regards
Kesava Pillai

Dear Mr Sharma,
Thanking the gentleman for posting an informative PPT would be appropriate which 99% of us would never known-then treating it with disdain.
Jude

Dear hseofficerjsk,
Your question:
what is the maximum height of
1) step ladder
2) straight ladder
3)extension ladder
Answer is attached
For 4)ladder used for scaffolding acess : max. height is 30 feet
Regards,
Kesava Pillai

I seen a ladder safety book by osha having explanation regarding 4:1 height to base ratio from this book i understand this ratio is for keeping ladder in a safe angle of 75 degree and to prevent accidental slips while climbing .this is explained in page number 11 of this book it also give explanation how to achive this ratio
Achieving a 4:1 set-up angle
A non-self-supporting ladder should have a
set-up angle of about 75 degrees — a 4:1 ratio of the ladder’s working length to set-back
distance.
Here’s how to achieve it: Stand at the base of
the ladder with your toes touching the rails.
Extend your arms straight out in front of you.
If the tips of your fingers just touch the rung nearest your shoulder level, the angle of your
ladder has a 4:1 ratio