225.19(e) Zone for Fire Ladders
- Thread starter OHHV
- Start date
- Status
charlie
Senior Member
- Location
- Indianapolis
OHHV said:
(E) Zone for Fire Ladders. Where buildings exceed three stories or 15 m (50 ft) in height, overhead lines shall be arranged, where practicable, so that a clear space (or zone) at least 1.8 m (6 ft) wide will be left either adjacent to the buildings or beginning not over 2.5 m (8 ft) from them to facilitate the raising of ladders when necessary for fire fighting.
This would be enough space for the ladder trucks to get set up and to extend their ladders to the floors above without overhead conductors being in the way. Normally this would not be a problem; however, balconies, trees, other utilities, etc. could interfere and a fire will not wait for a tree to be removed or a set of overhead conductors to be removed. :smile:
Charlie,
Looking at the NESC, table 234-1 it states that up to 22kv P-G a conductor must be 7.5' from building horizontally and a rigid live part (OH transformer bushing) must remain 7' from building horizontally. The exceptions are if no one will ever work on the outside of the building (painters,washers,etc) or if a protective baffle is installed, then that distance can be reduced by 2'. That would bring the distances down to 5.5' and 5'. When I read 229.19(E) from the NEC, I'm not certain how to interpret the 6' and/or the 8' rule. I understood the purpose of it, but the wording is unclear. (6 ft) wide will be left either adjacent to the buildings or beginning not over 2.5 m (8 ft) from them
Looking at the NESC, table 234-1 it states that up to 22kv P-G a conductor must be 7.5' from building horizontally and a rigid live part (OH transformer bushing) must remain 7' from building horizontally. The exceptions are if no one will ever work on the outside of the building (painters,washers,etc) or if a protective baffle is installed, then that distance can be reduced by 2'. That would bring the distances down to 5.5' and 5'. When I read 229.19(E) from the NEC, I'm not certain how to interpret the 6' and/or the 8' rule. I understood the purpose of it, but the wording is unclear. (6 ft) wide will be left either adjacent to the buildings or beginning not over 2.5 m (8 ft) from them
charlie
Senior Member
- Location
- Indianapolis
I am having some difficulty understanding what you are doing. The NESC applies to the serving electric utility and 225.19 is in the 600 volt and under section of Article 225. The applicable portion of Article 225 would be Part III or more particularly Section 225.61 if you are dealing with over 600 volt lines and it sounds like you are.OHHV said:
Is it safe to assume you are dealing with feeders from a primary metered installation or are electric utility lines next to and serving this building? Without more details, no one can really help you. :-?
Sorry for the confusion. I'm working for the utility company. My concern is regarding the secondary conductors that run parallel on the pole line, not the service drops. Our spec calls for a minimum of 5' 6" horizontally from pole-mount secondary rack to a building. When I read the local electrical code which is the same as the NEC 225.19(e), I questioned if that should supersede the NESC for some reason. My guess is that 225.19 does not apply to my case, but my confusion is that it doesn't distinguish between conductor types (utility secondary, service-drop or service-entrance conductors) and only states "overhead lines". That can be misunderstood as the utility company's secondary conductors carrying 120V to 480v.
charlie
Senior Member
- Location
- Indianapolis
An electric utility is required to follow the NESC . . . period. Also consider that the NESC is a performance document and, as such, we have to apply sound engineering principals to the various rules. Table 234-1 is the applicable table and no provisions are made for any fire ladders. I believe the reason is that our trouble men or a line crew will be able to kill the overhead lines or cut them so fire ladders may be used. I agree with your interpretation of the NESC in this regard (by the way, don't forget conductor blowout under max. sag conditions).OHHV said:
Now to get to engineering principals. If you feel like the amount of time to get to a fire would be excessive and there is no other place to set up a fire ladder, then good engineering principals would require you to build the line with more clearance to the building. If you have doubts, I would highly recommend a field meeting with the local Fire Chief to get his input. Additionally, if you think this should be spelled out in the NESC, you might consider a proposal to the 2012 NESC. :smile:
Charlie,
I was searching through the NESC this morning for another issue and coincidentally came across this exact rule. In Rule 234C5, it states the same thing as the NEC does. When reading the NESC handbook, it explains that the zone is set up for fire fighters to raise their ladders and put them on a building without interfering with the power lines. I think the original intention was for manual ladders, but the rule still remains here today. The problem is that the wording is not very clear. Do they mean primary or secondary spanned lines (pole to pole) or do they mean service drops?? If they only provided a picture which would probably say a thousand words...
What does the 6' and 8' rules mean to you? Please explain. Also, do you know if this is the only place to ask power company/NESC related questions?
I was searching through the NESC this morning for another issue and coincidentally came across this exact rule. In Rule 234C5, it states the same thing as the NEC does. When reading the NESC handbook, it explains that the zone is set up for fire fighters to raise their ladders and put them on a building without interfering with the power lines. I think the original intention was for manual ladders, but the rule still remains here today. The problem is that the wording is not very clear. Do they mean primary or secondary spanned lines (pole to pole) or do they mean service drops?? If they only provided a picture which would probably say a thousand words...
What does the 6' and 8' rules mean to you? Please explain. Also, do you know if this is the only place to ask power company/NESC related questions?
charlie
Senior Member
- Location
- Indianapolis
That is interesting and I have never seen Rule 234C5 or it has never registered (I need to read more). I do not believe manual ladders was the intent because that would be a very unwieldy ladder. When looking at this rule in the context of where it is placed, the lines covered are communications lines and grounded guys and neutrals to 22 kV and above. In other words, I see this as all inclusive. Also, this rule is inclusive of service drops and (5) is just a part of (C).
The 6' and 8' rules are the same as the 110.26 clearance rules in the NEC. This is a starting point of providing the necessary clearance for ladder access to the building. With the NEC, you picture a refrigerator packing crate in front of a panelboard and start applying the clearance rules for working space. This is just a bigger refrigerator.
I would assume you can contact Alan Clapp for a fee but I know of no place to ask NESC related questions in a bulletin board format. If you post questions here, the area you have chosen is a good place to post. Also, I am not the only utility guy here and I am not an engineer even though I retired from being an engineering supervisor. :smile:
The 6' and 8' rules are the same as the 110.26 clearance rules in the NEC. This is a starting point of providing the necessary clearance for ladder access to the building. With the NEC, you picture a refrigerator packing crate in front of a panelboard and start applying the clearance rules for working space. This is just a bigger refrigerator.
I would assume you can contact Alan Clapp for a fee but I know of no place to ask NESC related questions in a bulletin board format. If you post questions here, the area you have chosen is a good place to post. Also, I am not the only utility guy here and I am not an engineer even though I retired from being an engineering supervisor. :smile:
- Status