MAD for residential service drops

ghostice said:
So this discussion maybe begs one more question - whats the amount of juice going to streetlights? Still 120 V? I’ve hung a branch on one of the lines going to a street lamp years ago and some of em seem to have pretty thick copper coming up from the buried portion. Cheers
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I don't deal with street lights around here. We just don't have any. But I believe most, if not all are 120 or 240 volts.
The reason (I'm guessing) for a thick copper conductor is that they probably have many lights on the same line and need the current capacity for a lot of lights. As in, big wire for large breaker. Think about your house. You have 15 amp breakers with 14 gauge wire (small stuff). You have a 50 amp breaker for your electric stove (electric clothes dryer, etc) with big 6 gauge wires. Going into your main panel you have 200 amp main breaker with 4/0 wire (The thumb size wire) coming into it. It is all 120/240 volts. But the more things you put on a line, the more current they draw, so the wires need to be bigger. Does that make sense? Wire size has nothing to do with voltage, just current.
A 7200 volt primary is usually about the size of a pencil, and it is fused maybe at 15 amps someplace down the line. After it is run through the transformer and going to your house at 120/240 it is about the same size but at 200 amps.
If I am confusing you, let me know and I will back up and try it again.
 
ghostice said:
Great answer - thanks guy. I wouldn't expect to really have to worry about a streetlamp supply wire more than a drop to a house but what do I know for sure?
Cheers
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There are some laws that regulate streetlight voltages, and I am pretty sure it must be 120 or 240. I assume it is to protect those who take down the streetlights with their cars and the firemen who have to extricate those idiots.
Biggest thing to worry about with streetlights are the bulbs with high pressure sodium. Don't want to be messing with those. They won't zap you, but they might blow up in your face if you manhandle them. Not a giant boom, but picking glass out of your face is no fun.
 
Google and you shall receive yer meat and ptaters. Good read



On the Hotstick ranges, 120V wire 6feet elevation -focused antenna- 6" at same time 20 feet or closer to pick up a 7.2 kV or 16 kV overhead primary. If you visually stay more than 20' from known hot primary you can focus on local 120V - my read of the manual. 1" to pick up 120V on wet ground


An aha moment from the ESA writeup on sodium lamps:
High pressure sodium ballasts have a starting aid in the form of an electronic solid state circuit which provides superimposed pulses of 2500 or 4000 V ± during starting (see Figure 8 ). This is in addition to the normal magnetic circuit that controls the open circuit voltage and limits the lamp current. A full range of lead or lag ballasts are available, giving a high power factor of 90% plus or a low power factor of 50%. Because of the relatively high voltage starting characteristics of these ballasts, the life span may be reduced when they are left connected to a defective or burnt out lamp over an extended period of time. It is also extremely dangerous to attempt to change lamps while the electrical circuit and ballast are alive. This results from the fact that a regular starter will continually supply high voltage pulses to a burned out lamp, broken lamp, or an empty socket. A “protected starter” can be used to eliminate voltage being supplied to a burned out lamp, broken lamp, or an empty socket.
 
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Bart_ said:
Google and you shall receive yer meat and ptaters. Good read



On the Hotstick ranges, 120V wire 6feet elevation -focused antenna- 6" at same time 20 feet or closer to pick up a 7.2 kV or 16 kV overhead primary. If you visually stay more than 20' from known hot primary you can focus on local 120V - my read of the manual. 1" to pick up 120V on wet ground


An aha moment from the ESA writeup on sodium lamps:
High pressure sodium ballasts have a starting aid in the form of an electronic solid state circuit which provides superimposed pulses of 2500 or 4000 V ± during starting (see Figure 8 ). This is in addition to the normal magnetic circuit that controls the open circuit voltage and limits the lamp current. A full range of lead or lag ballasts are available, giving a high power factor of 90% plus or a low power factor of 50%. Because of the relatively high voltage starting characteristics of these ballasts, the life span may be reduced when they are left connected to a defective or burnt out lamp over an extended period of time. It is also extremely dangerous to attempt to change lamps while the electrical circuit and ballast are alive. This results from the fact that a regular starter will continually supply high voltage pulses to a burned out lamp, broken lamp, or an empty socket. A “protected starter” can be used to eliminate voltage being supplied to a burned out lamp, broken lamp, or an empty socket.
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Good read for those of us who understand what is being said. Probably not such a good read for the average person.
I found it interesting however. Learned a bit more about grounding and bonding of streetlight equipment.
Thanks for the link.
 
Not sure if it’s already been mentioned, but anyone know what the minimum distance would be that you should maintain from a service drop / communication lines in a lift / bucket that isn’t insulated?

Most lifts you are able to rent aren’t insulated right?

Now would that minimum distance include where your tools can go if they are potentially conductive? So in other words unless you’re reaching in with a non-conductive pole pruner or something, NOTHING should cross that threshold.
 
Shadowscape said:
See page 1
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I have, and I've also browsed through the other pages.

I know 10ft is recommended, but even though it's still recommended there are situations where you can still safely work within 10ft proximity to them. I did just the other day, from the ground with a non-conductive pole pruner near a service drop and communication lines.

My question is specific to being in a lift that isn't insulated, would you want to maintain an even further amount of distance than that 10ft, or would 10ft be sufficient? And if all parts of the lift are safely outside of that 10ft distance, any tools you stick into that 10ft radius would need to be non-conductive I'm thinking? Because of the fact that you are essentially connected to a big piece of metal, etc. that could act as one big conductor.
 
climbingmonkey24 said:
I have, and I've also browsed through the other pages.

I know 10ft is recommended, but even though it's still recommended there are situations where you can still safely work within 10ft proximity to them. I did just the other day, from the ground with a non-conductive pole pruner near a service drop and communication lines.

My question is specific to being in a lift that isn't insulated, would you want to maintain an even further amount of distance than that 10ft, or would 10ft be sufficient? And if all parts of the lift are safely outside of that 10ft distance, any tools you stick into that 10ft radius would need to be non-conductive I'm thinking? Because of the fact that you are essentially connected to a big piece of metal, etc. that could act as one big conductor.
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Minimum approach distance charts apply to you, anything you are standing on or eating, and anything you are holding. They also apply to any parts of the tree that you are working on. According to the chart, you may not ever go within 10 feet of any line unless you are qualified to work closer. You also may not put your tools within 10 feet of any line, And you may not work on a tree that is within 10 feet of any line. The charts are very strict, so they are frequently violated, that is what chart says.
 
Reach said:
Minimum approach distance charts apply to you, anything you are standing on or eating, and anything you are holding. They also apply to any parts of the tree that you are working on. According to the chart, you may not ever go within 10 feet of any line unless you are qualified to work closer. You also may not put your tools within 10 feet of any line, And you may not work on a tree that is within 10 feet of any line. The charts are very strict, so they are frequently violated, that is what chart says.
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I'm well aware of that 10ft rule, but let's be honest how many people here have come within 10ft of a service drop before who aren't certified in electrical work? Most if not all? If you have a basic understanding of the potential hazards I think an individual with the right knowledge can work around them a little more safely under the right circumstances. And that isn't meant to sound arrogant or a lack of appreciation for the dangers, quite the contrary actually.

Maybe I wasn't clear what I was saying. If you are in a lift that isn't insulated, would it be approriate to INCREASE that MAD distance to say 12-15 ft just because of the fact it isn't insulated, or would 10ft still be sufficient?

Not sure if that makes sense...

I don't think I have once ever worked near lines in a lift anyhow, but it's something I am curious about.
 
climbingmonkey24 said:
I'm well aware of that 10ft rule, but let's be honest how many people here have come within 10ft of a service drop before who aren't certified in electrical work? Most if not all? If you have a basic understanding of the potential hazards I think an individual with the right knowledge can work around them a little more safely under the right circumstances. And that isn't meant to sound arrogant or a lack of appreciation for the dangers, quite the contrary actually.

Maybe I wasn't clear what I was saying. If you are in a lift that isn't insulated, would it be approriate to INCREASE that MAD distance to say 12-15 ft just because of the fact it isn't insulated, or would 10ft still be sufficient?

Not sure if that makes sense...

I don't think I have once ever worked near lines in a lift anyhow, but it's something I am curious about.
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The minimum approach distance is sufficient. That is why it is called the minimum approach distance. Doesn’t matter if you’re in a metal lift or not, as long as you stay outside of the minimum approach distance you are fine. There is no need to increase it, unless you are working at very high altitudes, in which case the chart makes the increases for you.
 
As long as you are 10' away you are good under all circumstances you are likely to encounter.
You are not going to get anyone to tell you are okay to work closer than the 10 ' rule no matter how careful you are and how aware you are of the dangers. Isn't going to happen. And it doesn't matter how many others have broken the rule. It doesn't matter what I think, or what anyone else thinks.
Until the rule changes, 10' is it.
 
Considering that the OSHA distance is much smaller than 10 ft i.e. 1 foot from the Klein manual, you should feel confident at 10 ft. Plenty of margin. IMO

Remember that's 10 ft from the tool you're extending out i.e. the tip of your polesaw. 10 ft gives you margin for if you do something like stumble.

A more practical concern is presence of moisture like rain dew or condensing fog. That'll conduct and weed out any poor grounding issues as per the news articles about your dog getting zapped walking down the sidewalk or touching a guy wire etc. If it starts to rain you got more to worry about than lightning.
 
Ok I think I have one that hasn’t been asked yet. MAD for the person or the tool the person is holding. That is clear, but what about the tree. The hypothetical is if there is a uninsulated wire a few feet from a limb (1-6’ for a spitball) on the far side of a maple or oak, and the work order is to prune and cable the tree. None of the work comes within MAD. What is the legit standard with this?
I doubt this answer would change if it’s a ‘insulated’ house drop, does it?
 
evo said:
Ok I think I have one that hasn’t been asked yet. MAD for the person or the tool the person is holding. That is clear, but what about the tree. The hypothetical is if there is a uninsulated wire a few feet from a limb (1-6’ for a spitball) on the far side of a maple or oak, and the work order is to prune and cable the tree. None of the work comes within MAD. What is the legit standard with this?
I doubt this answer would change if it’s a ‘insulated’ house drop, does it?
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My understanding, is that if the tree is within the MAD, technically you may not be in that tree. I have not seen anything in writing one way or another to prove it though, at least not from an official source, so I can’t guarantee that I am correct.
 
I just woke up so I may be interpreting the question wrong as my brain is only running of half cylinders at the moment. But, if you are asking, can you be in a tree and maintain the 10 foot distance even though parts of the tree are closer than 10 feet to the line?, then yes, you are allowed to be in the tree that is within the zone as long as you and your tools remain beyond the 10 foot limit to the line, and that includes your ropes. It is one of those, WHAT IF rules. As in, what if the tree is touching the line and it is raining and the tree is all wet? The rule does not get specific as to the WHAT IF questions. Just that you and your equipment must remain beyond the 10 foot range. So, in reality you can actually cut a limb off that is touching a live powerline if the limb on the line is at least ten feet from your cut. OSHA does not consider the tree as conductive material (but drop a limb across two phases of a 50KV line and get ready to be engulfed by a fireball).

That said, I am not saying you should cut a limb touching a power line if you are unqualified. And if it is a primary line that any part of the tree is within the 10 foot zone, I would stay out of the tree if you are unqualified. That is my opinion only.
 
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Primary lines are the nasty ones that jump arcs through the air and through seemingly insulative items like branches. I've turned down prunes where the far side of the tree is within primary MAD (for the higher voltage) because an unexpected event could put you in contact with energization via the tree. An error - 220V OSHA is "avoid contact" not 1 ft, confirming Shadowscape's tech analysis of your drier cord is safe to touch. So your safety sense has to turn on Hi when you spot primaries.

Reading some OSHA stuff, they contingent their distances not only on the normal voltage but on the of chance a 2 or 3x transient fires itself down the line from switchgear operation etc. Safety first, Robin...

Who was the guy who said more-er safer-er-est way back when? old memories old posts Say it to retired teachers then play Live and Let Die "This world in which we live in..." I got one teacher customer and I go to the well once in a while. Brightens up the day :)
 
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