Guy wire

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Location
Saint Louis, MO
Occupation
Electrical Contractor
At what height do you guys typically run a guy wire for service mast? POCO and AHJ both do not have an answer. However, the inspector told me I need a guy wire. Not because of measurements. She didn't climb up. But... It is 2in rigid. And 24 in from the roof line.. All the POCO and AHJ have to say is it needs to be supported adequately. Which it is. Thoughts?

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James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
Evergy (formerly Kansas City Power and Light) requires guy wire for masts more than 24" above roofline

I've never met a city inspector who thinks it's his job to give an opinion
 
Location
Saint Louis, MO
Occupation
Electrical Contractor
I'm in St Louis so we have Ameren. They don't give a number. But...to solve this problem. I'll pull my wire back out and cut it down to 23 to the top of the weatherhead. Stick the tape measure up to it and take a pic. The min is 18in. Maybe that will work?

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James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
I'm in St Louis so we have Ameren. They don't give a number. But...to solve this problem. I'll pull my wire back out and cut it down to 23 to the top of the weatherhead. Stick the tape measure up to it and take a pic. The min is 18in. Maybe that will work?

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That would work around here, as long as your clamp-on insulator is at least 12' off the ground
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Here, anything over 42" has to be guyed. We have several POCOs we deal with, most things are different with each POCO, surprisingly, the 42" is consistent with them all.
 
Location
Saint Louis, MO
Occupation
Electrical Contractor
Let's be honest here. Is installing a guy difficult or costly...no. But, the AHJ and POCO wouldn't give me an answer. And, in situations like this I would rather learn what they require rather than running and grabbing material and eating the cost just to satisfy them and complete the job a little quicker. Sure maybe it's just that one inspector. But the knowledge will still be in my mind and here for others.

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James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
If I know I have a riser going through a roof, I'll take an eye hook, cable, crimps and a swaging tool - and some roofing caulk.

But usually I've already measured the height, and I already know if I need a guy wire. It's in the bid, too. $150.00
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
The NEC just says that it needs to be adequate to support the drop. The mast height is important but so it the distance from the pole. A 25' drop could probably go on a 10' mast without guy wire.
 

retirede

Senior Member
Location
Illinois
The NEC just says that it needs to be adequate to support the drop. The mast height is important but so it the distance from the pole. A 25' drop could probably go on a 10' mast without guy wire.

The amount of tension required to achieve minimum height will also affect the load on the mast.

I agree, making it a requirement based solely on mast height is not sound from an engineering standpoint. Which is why they can’t tell you guy wire parameters.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I'm in St Louis so we have Ameren. They don't give a number. But...to solve this problem. I'll pull my wire back out and cut it down to 23 to the top of the weatherhead. Stick the tape measure up to it and take a pic. The min is 18in. Maybe that will work?

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That is interesting. Ameren Illinois has a table showing the maximum height of the attachment point above the roof without a guy. If a guy is used they say it must have adequate strength and be approved by them. This is based on a service drop length not exceeding 100'

Table 1. Maximum Attachment Height Above Roof (Note 8)
AmperesPhaseAmeren Service Drop Size2" Rigid Steel2.5" Rigid Steel3" Rigid Steel
100 amps1#2 AL Triplex2 ft, 2 in.4 ft, 1 in.
200 amps1#2 AL Triplex2 ft, 2 in.4 ft, 1 in.
200 amps11/0 AL Triplex4 ft
200 amps31/0 ALQuadplex4 ft
400 amps14/0 AL Triplex4 ft
400 amps34/0 AL Quadplex4 ft
 
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