JanLCA
Structural
- Apr 6, 2002
- 4
Help! It's mind boggling. I must have misinterpreted it.
1977 Natinal Electrical Safety Codes, Rule 250B (Ice and Wind) Loadings specified 40 mph on cables/wires (supported facilities) and on poles (support structures.
However, Rule 250C (Extreme Wind) Loadings specified that extreme wind (80mph in my case) load provisions do not apply to supported facilities (cables/wires) below 60ft (18m) but apply to support structures without conductors from ground up.
What am I missing here? Why support structure experiences the extreme 80mph wind from ground up and wires below 60ft don't?
Can anyone clarify it for me? I am structural guy and read this code the first time. it is an education.
I am dealing with mono H-Column steel poles supporting few groups of cables at 40 ft high. I am evaluating the structural capacity of early 1920 poles for supporting proposed new 3 group of cables.
Thanks.
1977 Natinal Electrical Safety Codes, Rule 250B (Ice and Wind) Loadings specified 40 mph on cables/wires (supported facilities) and on poles (support structures.
However, Rule 250C (Extreme Wind) Loadings specified that extreme wind (80mph in my case) load provisions do not apply to supported facilities (cables/wires) below 60ft (18m) but apply to support structures without conductors from ground up.
What am I missing here? Why support structure experiences the extreme 80mph wind from ground up and wires below 60ft don't?
Can anyone clarify it for me? I am structural guy and read this code the first time. it is an education.
I am dealing with mono H-Column steel poles supporting few groups of cables at 40 ft high. I am evaluating the structural capacity of early 1920 poles for supporting proposed new 3 group of cables.
Thanks.