Responding to Manhole Fires

[CPOPE]

Somthing you might want to review with local supervison and Fire Depts,

This is the electric manhole fire season in those areas where cold weather, snow, and slippery roadways necessitate the placement of ice-melting salt onto roadways to make them safe. When the salt is put on top of slick roads, the result is a melting of the ice and snow that coats them. As a result, the roadway becomes safely passable but at a price. The mixture of salt and melted snow and ice filters into manholes, coating the underground electrical wiring and equipment. This salt-water cocktail is very corrosive and causes the wiring, transformers, and other elements of the underground electrical delivery system to deteriorate, sometimes resulting in arcing exposed wires. The arcing, burning wire generates various toxic and combustible gases including high concentrations of carbon monoxide and neoprene gas. These gases are contained in the black noxious smoke billowing out of the manhole at a manhole fire.
Firefighters and troubleshooters responding to these incidents should be aware of the many hazards that may accompany this phenomenon.

1. The black smoke can at any moment suddenly ignite, exposing people and vehicles nearby. A person inside a car parked over such a manhole would be severely injured or killed should the smoke ignite as he tried to move the parked car away from the manhole.
2. The ignition can be explosive, sending the 300-pound manhole cover flying into the air. Manhole covers have been blown onto the roofs of six-story buildings and have gone up in the air only to come crashing down through the roofs of passing vehicles.
3. Manholes are connected underground to other manholes by electrical conduit through which wires pass. Fire in one manhole can spread to other nearby seemingly uninvolved manholes, which can suddenly start to smoke, erupt into flames, or blow their covers into the air.
4. The explosive and toxic gases created at these incidents can pass through underground conduit into surrounding structures served by the underground electrical delivery system. The result can be overcome occupants and an explosive atmosphere in the electrical service box or the entire building. These explosive gases can also travel along underground conduit and enter and fill up hollow street light poles. A spark from a traffic light control box can ignite these gases, causing the lights' access panels to blow off the poles.
5. Salt water is a good conductor of electricity and, as a result, manholes and grates covering underground electric equipment have become energized, resulting in the deaths of passing pedestrians, pets, and in one case a carriage horse. A metal bus stop shelter and metal curb strip became charged in one instance; in another, a nearby hydrant was charged.
6. Flowing water into a burning manhole could result in electrocution of the firefighters on the line and could cause an explosion. It could also force the CO in the hole through conduits into other manholes or structures.
When responding to these incidents take the following actions and precautions:

1. Notify your electric utility to respond.
2. Stay clear of the trouble manhole.
3. Stop any traffic that might be endangered by a flying manhole.
4. Find and stay clear of the next manhole on either side of the trouble manhole.
5. Check nearby structures for carbon monoxide and evacuate them, if necessary.
6. Do not attempt to kill the power to a building, even if its lights are blinking; there could be an explosive atmosphere in the electric panel box. A spark created by opening the main cut-off could result in an explosion.
7. Do not flow water into manholes until requested by your electric utility. When requested to flow water, do not flow it directly into the manhole from a hoseline. Bounce it off of the street and let it flow along the ground into the manhole or, better still, let water from an unmanned open butt flow into the manhole.
8. Be aware that the danger area around a burning manhole may extend to other manholes, nearby street light poles, and traffic control boxes as well as the surrounding structures. If electric service is delivered by a combination of overhead and underground wiring, be aware that a manhole fire can extend up to the overhead wires via a connecting conduit. This would put the run of overhead wiring in the danger area.Manhole fires often do not have catastrophic results-they can often be concluded without explosions and without having to evacuate buildings. However, conditions can change without warning from lazy smoke seeping from a manhole to smoke billowing out under pressure. The smoke can suddenly erupt into flame or explode. Use caution and common sense when responding to these incidents. Seek and heed the advice of your utility representative and expect the unexpected. A manhole response is not a "routine" response. There are no "routine" responses

[Bull Dog]

Why do you post all this. If you want to teach in a line school go ahead but most of us have been there and done that. You are just stating the obvious.

[Hemingray Insulators]

what may be obvious to you might not be so ppl with less experience or apprentices, so it does help some people, b/c i have learned a few things by reading it;)

[Bull Dog]

You are right Brian but you know how boring this is to the old hands on here. I do see your point though. A little less of the line school though would be nice. I personally get bored with it. Its all new to you so you like it. I don't. I wish you the best Brian good luck. Always think first then do cause I don't want to read on here you got hurt. On the other hand don't let it scare you. A healthy respect is what you need. Thanks for posting.

[Chazz2771]

I thought it was a good post. I'm also a volunteer firefighter, and the only thing that we are ever taught is that 99% of the time if it is anything involving power lines we just go there and keep everybody away and wait for the power company to show up. Good post though, I wish there were more like this. Forums are a great place to learn things and not just shoot the sh!t. You old timers should post stuff like this and other things you know or have learned over the years. What you might think is "useless knowledge" just might save somebody's life some day, or at least a world of hurt.

[PA BEN]

We have 3 phase primary manholes with large heavy lids on them in the middle of streets. It would be good for fire depts to know that the lid could fly off at any time. Most of the time the fire dept. gets on seen before linecrews do.

[CPOPE]

We have 3 phase primary manholes with large heavy lids on them in the middle of streets. It would be good for fire depts to know that the lid could fly off at any time. Most of the time the fire dept. gets on seen before linecrews do. It does take balls to lift the cover off a a smoking MH. The inrush of O2 can cause flashover.

Some of this is old hat to us all but even an old dog can learn a few new tricks. It's always better to have a plan than to fly by the seat of the pants. Trouble Shooters are first responders much like Fire Dept and/or Police. How many of us have seen Cops wandering around down conductors at P-Hits. I sure have. Countless times. Have heard about fire departmens refusing to flood Manholes at Elec Utility request. It happens. Foam works best I believe, not readily available, but again, you do not want to discuss it on the fly..........Have a planned response in place.

Ground rules on electrical hazzards for first responders are best established prior to an emergency response. Agreed? Plan the work. Work the plan. Sure it's a cliché but if your not working from the same page things go to shit quickly.

Just check out these links to reacent manhole fires.
http://www.wtoctv.com/Global/story.asp?S=9588832&nav=menu89_2
http://www.google.com/hostednews/ap/article/ALeqM5i1FFTstm5wPTpWh5K2jx0lu-0KqQD959JV280
http://gothamist.com/2008/12/22/if_its_snowy_there_will_be_manhole.php

Does your company have a planed response?

SEAPOPE Electrical Consulting LLc
CPONEIL@Charter.net
JOURNEYMAN #E31316
PE REGISTRATION #37843

[PA BEN]

I know of URD Manholes on the waterfront w/600 hammer heads, that are subject to ocean tidal water. And salt water doesn't effect them. I think the URD was getting ready to go anyway and the salty water put it over the edge. In any event manhole fires are Dangerous.

[BigClive]

I'm guessing the ones that get ocean water in them will be suitably designed and spaced internally to limit the risk of fires.

The ones getting salty road water washed into them sound like they are an old system that was never really designed for that scenario, and aren't being subject to suitable modernisation. Maybe when they go on fire that's the cue to modernise. :D

The use of modern chemical "salt" for ice removal is definitely causing more issues than plain grit alone did. The road spray coats insulators and causes tracking, so it may be that modern ice removal chemicals are the main issue with manhole fires.

[australiantroubleman]

Not living in a climate that has snow or ice in winter we dont have any salt issues in my area.
I used to work for a company with a extensive underground system of substations and infrastructure , had a few problems mainly with gas entering street ducts and heavy rain flooding vaults, these days you need a confined space permit , gas test ,full rescue team with tripod and rescue equipment set up before entering these areas can take hours to gain access for a five minute job.

Years ago we worked in them with no safety equipment or training .. times sure have changed.

[Lizzy Bordon]

One of First Energy's fatalities was caused by exactly what you are talking about at the Jersey Shore the salt air corrodes a lot of the equipment. Rule of thumb was copper from the railroad tracks toward the ocean.

I bet the families of the guys who died that day would have liked a heads up. The had quite a few years in the cable department. One had a brother who was also a lineman there.

[CPOPE]

Saturday, June 6, 2009
SAN FRANCISCO -- Pacific Gas and Electric Co. is trying to determine what caused an underground explosion and fire Friday in San Francisco's Tenderloin that sent 30-foot flames into the air and cut power to thousands of customers. -----------------------------------------------------------

http://imgs.sfgate.com/c/pictures/2009/06/05/ba-blast_0500234416.jpg--http://imgs.sfgate.com/c/pictures/2009/06/05/ba-blast_0500234414.jpg----http://imgs.sfgate.com/c/pictures/2009/06/05/ba-FIRE_0054_0500234022.jpg-------------------------------------------------------------------
The blast happened about 11:30 a.m. near Polk and O'Farrell streets. Flames and a plume of thick, foul-smelling black smoke billowed from a manhole for more than two hours.

No injuries were reported, but firefighters said they had responded to reports of people stuck in elevators in buildings without power.

At the height of the outage, 8,600 customers were in the dark, PG&E said. By evening, the total was down to 2,000 customers.

With possibly toxic smoke blowing through the streets and traffic lights not working, authorities closed off a two-block radius to traffic and urged people to stay indoors and shut their windows. The Fire Department declared the fire under control about 2 p.m. and lifted the shelter-in-place advisory.

The cause of the explosion and fire was under investigation. One possible culprit, PG&E said, is the underground transformer where high-voltage lines terminate and the power is converted into household current.

Transformers have exploded before in San Francisco, most notably in August 2005, when a blast on Kearney Street in the Financial District critically burned a woman who had been walking on the sidewalk.

In that case, the explosion was caused by high levels of moisture in the oil inside high-voltage chambers on the transformer. The source of the moisture was a leak.

After that accident, crews found five additional transformers with high moisture levels in the Financial District and South of Market.

So far, PG&E has not been able to get into the vault where Friday's explosion happened. "We will do a thorough inspection once we can get down inside there," utility spokeswoman Tamar Sarkissian said.

Firefighters at first used foam to fight the blaze, but backed off when PG&E officials asked them to let the fire burn out. Once they stopped, the black plume was replaced with roaring orange flames, reaching 30 feet at one point.

The sight drew crowds of onlookers, including Mayor Gavin Newsom and Police Chief Heather Fong. Several people wore dust masks, and police turned away residents who were trying to get to their homes.

J. Anthony Reed, 47, was watching the movie "The Hangover" at the AMC Theater on Van Ness when all the lights went out and the smell of burning rubber filled the theater.

The exit signs were also out, so Reed used his cell phone to navigate his way outside.

"The only thing I was thinking was getting out of there, getting out, out, out," Reed said. "I saw orange flames taller than these buildings. I thought the end of the world was coming on."

John Steele Jr. could smell the smoke from his apartment two blocks from the fire. "I had to get out of my building," he said, holding a sweatshirt to his nose. "The fumes were so noxious inside."

David Bristol, 40, was in an apartment building at 990 Polk St. when the hallway alarm sounded and he saw flames shooting from the manhole. He and a friend went down the fire escape, ran through the smoke and spent the next few hours grocery shopping.

"Well, we had to do something," he said. "Even now, my chest is bothering me. The smell is awful. I just wanted to get away as soon as possible."

Ali Ghanbarian, who runs a publishing company at Polk and O'Farrell, ran out of the office with his staff after they heard the explosion. He tried to drive his car out of the garage, but the electric door wouldn't open.

"We covered our faces, closed our office, and just left," he said. "We've been walking around doing errands."

The fire and electrical outage prompted the Fillmore music hall to cancel Friday night's appearance by hip-hop performer Del tha Funkee Homosapien. People who bought tickets can get refunds.

[SFCityguy]

That SFFD tanker truck in the picture is a CO2 unit. We provide the unit to them and ask them always to wait till we call for the CO2 dump. And NEVER dump your full load, just in case it flares back up.

[CHICAGO HAND.]

We just had a 2 year memorial for a man who died in a manhole explosion. We have many concerns about the way we do our job in confined spaces. One thing we try and get is to put all the feeders on one shot but our mapping is so messed up we don't always know what feeders are in the holes.
We just had another incident two weeks ago of a splice blow as one man was exiting the hole. He heard it going and made his way out. I have a few issues that I would like to run by some underground guys off line if anyone could help me out.

[T-Man]

Look on your PM's

[CPOPE]

Updated: 05/09/2011 04:58:23 PM PDT
SETTING THE RECORD STRAIGHT (publ. 5/9/2011, pg. 2A)
A story about underground electrical accidents had the wrong first name of Mark Johnson, PG&E's vice president of electric transmission and engineering.

PG&E's natural gas lines aren't the only worry lurking underground. State regulators are concerned about the scores of incidents in recent years in which the utility's subterranean electrical gear has belched smoke, spewed flames and in some cases exploded with such force that 100-pound manhole covers were sent flying.

Research by this newspaper turned up at least 78 such mishaps in the Bay Area since 2005, the most recent of which occurred Wednesday, when residents near Delmas and Park avenues in San Jose heard a blast and about 1,000 PG&E customers lost power for about an hour.
http://extras.mnginteractive.com/live/media/site568/2011/0508/20110508__vaults1~1_GALLERY.JPG
While many of the accidents were minor, explosions were reported in 31 cases, with manhole covers dislodged in at least 14. Two people were injured, including Lisa Nash of Redwood City. She was burned over half her body and her right elbow was shattered by a manhole cover that was hurled 30 feet when an underground electrical vault erupted beside her as she strolled toward her San Francisco office in 2005.

"I remember opening my eyes, seeing a cloud of black smoke and thinking to myself, 'Thank God I can still see,' " said the 52-year-old Nash, who spent more than two months being treated at St. Francis Memorial Hospital's
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burn unit, which she praises for saving her life. Nash, who received a $20 million settlement after suing PG&E, said she can't recall the actual explosion and added, "I hope I never do."

Although fires and occasional manhole blasts have plagued PG&E's aging underground electrical gear for decades, the California Public Utilities Commission recently has decided to examine the problems in depth, according to its executive director, Paul Clanon. He said the inquiry is part of a broad look at dangers posed by various industries the commission regulates following the Sept. 9 explosion of a PG&E natural gas pipe in San Bruno, which claimed eight lives and destroyed 38 homes.

"As a result of San Bruno, we've done some soul-searching internally and looking at how we approach all of our safety programs," Clanon said. Given the potential for injury from underground electrical equipment, he added, "it's obviously something that needs attention."

PG&E packs a wide array of its gear into underground compartments -- which range from spaces barely big enough for one person to much-larger cubicles called vaults -- and it's unclear if any single factor other than the equipment's age is causing it to fail so frequently.

No one in the Bay Area has been killed when these chambers erupt, but the events often knock out power to the surrounding area and can be terrifying.

In August, residents around East Capitol Expressway and Silver Creek Road in San Jose reported hearing an explosion and feeling the ground shake from an underground electrical compartment that caught fire. In September 2009, another San Jose incident in the 1900 block of Loch Ness Way spit four-foot flames amid clouds of black smoke and knocked out power to 300 homes. And in September 2005, an underground electrical blast in Berkeley heaved a manhole cover onto a Mercedes, whose driver was injured by an air bag that inflated after the impact.

But the vast majority of the incidents -- and some of the most spectacular -- have occurred in San Francisco, which has the greatest concentration of PG&E's underground electrical devices, according to company officials. Of the 78 incidents this newspaper counted since 2005, 62 were in San Francisco, making its streets at times as seemingly precarious as a minefield.

On March 28 of this year, Union Square shoppers were startled when an underground power cable failed, triggering a blast that sent a manhole cover flying on Grant Avenue.

On June 24, 2008, an underground explosion near California and Drumm streets blew fragments off two manhole covers, frightening office workers and shaking buildings.

On Dec. 18, 2005, a failed electrical switch caused an explosion near Jackson and Locust streets with such force a fire department report said it split a cast-iron manhole cover in half and pushed up a concrete slab.

The repeated accidents have left some San Francisco officials deeply frustrated.

After the Aug. 19, 2005, explosion that burned Nash, then-mayor Gavin Newsom warned, "enough is enough, excuses be damned "... If this happens again, PG&E is in real trouble." After another detonation in 2007 reportedly shot flames six feet high, the utility formally apologized to Newsom. Yet more accidents occurred, including one the morning after the San Bruno gas-line eruption, prompting Newsom to declare, "I can't accept another."

Since then, San Francisco has had at least two more mishaps. But Mark Johnson, PG&E's vice president of electric transmission and engineering, insisted his company has been working hard to minimize the incidents. He noted that PG&E spent about $200 million from 2007 to 2009 to upgrade its aged subsurface gear in San Francisco and is installing 350 specially designed manhole covers that won't fly off in a blast.

"Safety to our employees and the public is our highest priority," he said. "So any time you have a failure, we're concerned about it."

Underground electrical fires and explosions sometimes result from equipment that short-circuits or when oil leaks from transformers and switches, according to a study by corporate giant Siemens. Another cause is combustible gas that is released by deteriorating electrical cables or filters into the vault from nearby natural gas and sewer lines.

San Francisco Fire Department spokeswoman Lt. Mindy Talmadge praised PG&E for training firefighters to deal with the accidents and for giving her department special equipment to extinguish electrical fires. She added that the number of such incidents seems to be dropping off. Yet the department's data failed to include 17 incidents this newspaper turned up from news stories, including several reports which indicated that her department had responded.

The statistics kept by PG&E and the Public Utilities Commission are similarly inconsistent.

While this newspaper counted 78 Bay Area underground mishaps since 2005 PG&E said before Wednesday's incident that it knew of just 35 throughout its entire service territory, which covers 70,000 square miles from Eureka to Bakersfield. The California Public Utilities Commission -- which only tracks the worst accidents -- said it is aware of 11 PG&E incidents during that period, six for Southern California Edison and none for San Diego Gas & Electric.

Nationwide statistics also are inconsistent, according to George Gela of the Electric Power Research Institute, who has studied the subject. But while his organization notes in a brochure that "the energy released in a major manhole explosion is equivalent to several sticks of dynamite," Gela said "your chances of injury in a car are much greater."

Even so, Nash, who is CEO of Blue Planet Network, which promotes safe drinking water worldwide, said PG&E needs to do more "proactive maintenance" to make sure no one else experiences what she has endured.

Although she has largely recovered from the accident, to this day, she said, "I walk around every manhole cover I see."http://www.mercurynews.com/san-bruno-fire/ci_18020802?source=rss&nclick_check=1

[CHICAGO HAND.]

We just had an explosion late last week right after the crew exited the hole. We have had way to many close calls and I hope we never see another fatality because of this problem.

[BigClive]

We just had an explosion late last week right after the crew exited the hole. We have had way to many close calls and I hope we never see another fatality because of this problem.

Oh, nasty. I'm very glad they got out before it happened. Was there any clue it was going to occur?

[CHICAGO HAND.]

I don't believe there was any indication of a pending failure. We have been pushing with some success to put all feeders on one shot and we now have a thermal imaging camera to check for hot spots in the splices. We also have a bomb blanket to put as a barrier between us and the splices but it is not always practical or possible to use. The company is on high alert because of three near misses this last week.

[Lineman North Florida]

I don't believe there was any indication of a pending failure. We have been pushing with some success to put all feeders on one shot and we now have a thermal imaging camera to check for hot spots in the splices. We also have a bomb blanket to put as a barrier between us and the splices but it is not always practical or possible to use. The company is on high alert because of three near misses this last week.Several years ago we went through and looped all the radials that were fed off of the trayer gear in most of our manholes, there are usually 3 different circuits going through most of these manholes and although most of loops are now dual circuit loops and you have to blink lights on one end to keep from blowing fuses it allows us to de-energize switchgear and get a clearance on a manhole, if I can find the picture that was taken many years ago it shows a ball of fire coming up out of a manhole and me running away from it with hot oil going everywhere, all I was doing was pumping the water down so I could get ready to change out a bad trayer gear that had blew the mh cover off and dispatch messed up on there switching and closed the cable right back in on the faulted trayer gear that I had isolated and I can say that my opinion is that those blast blankets would do a lineman little or no good if a fault occured in a manhole that he was in, I said all of that to say this, I used to work in energized manholes pulling wire, making up t-housings, elbows etc and had a false sense of security with blast blankets and other things that were provided to us by the company before I new better, bottom line it is expensive to loop your system and make it to where you don't have to knock a lot of customers out, but it's well worth it if it saves one linemans life, afterall it's not overhead where you can see your hazards.

[CHICAGO HAND.]

I will take anything we can get. Our small holes have at least 6 main stem feeders fed usually right from the station. Our main cable size is 750 with very little urd cable in any of our holes. Rarely is any of the cable in our holes backed by a fuse, as I stated it all comes from the station. We have oil filled lead cable the closer you get to the city. The blanket may help keep the oil off us when it lets loose. The blanket and the one shot gives me the best protection we have found so far.
I too have seen the power behind this stuff. In 20 years I have seen enough to want to make it as safe as possible for the next guy.

[Lineman North Florida]

I will take anything we can get. Our small holes have at least 6 main stem feeders fed usually right from the station. Our main cable size is 750 with very little urd cable in any of our holes. Rarely is any of the cable in our holes backed by a fuse, as I stated it all comes from the station. We have oil filled lead cable the closer you get to the city. The blanket may help keep the oil off us when it lets loose. The blanket and the one shot gives me the best protection we have found so far.
I too have seen the power behind this stuff. In 20 years I have seen enough to want to make it as safe as possible for the next guy. We have a few holes with 4 different feeders of 1000 mcm in them but we try to limit them to no more than that, most have 3 feeders from the sub, sounds like your system is more complicated than ours, good luck on whatever protection you can get as I said earlier I believe there is very little protection for you if a fault occurs in a manhole that you are working in.