Have you ever caused an arc to occur?
Big arc or small, at work or at home, basically anywhere (above 50 volts, i.e. jumping a car battery doesn't count).

• Yes
• No

I will start this one off. YES - a very long time ago at my sister's house. Accidentally touched a conductor to the enclosure. Oops!

Well, I was the one there in charge when it happened, though it was actually two electricians that caused it. We were testing the breakers on a double ended 600V sub. We were changing from one single power source to the other. Due to a few issues both sources were closed in while the you're was still closed. One set of primary fuses blew with the other side breaker tripped. And we got writer a light show.

Yes, over the years I have managed to acquire several wire strippers that started life as wire cutters.

A while back when still at my parents, helping my dad change some light switches, the breaker wasn't off in the beginning. It went to the middle position when the screwdriver touched the live screw of the switch at the same time as the rear of the electrical box. Small "poof".
Can't recall something bigger than that, partly because now I now what not to do and how not to do it.

I've had a few as well. The most memorable ones are:

In the late 1980's, I was in front of an inverter that someone had put the fly-back diodes in backwards resulting in a very large flash and a big ball of plasma shooting out of the inverter.

In the mid-1990's, I was working on a test stand for motors that was fed by 6600 Volts. Due to some misinformation from the manufacturer, my Fluke 77 ended up across 6600 volts instead of the intended 600 volts. That one blew divots in the bus-bar, blew the ends off my test leads, blew up my meter, and killed the power to the entire plant.

Assuming we're talking about unintentional/uncontrolled arcs (welders, opening cutouts, drawout stabs that misalign, etc., don't count), and not counting things like inaction (did not do maintenance)...

Most recent ones within the last year were when removing a fume hood that had an extra/undocumented/unknown circuit in it, accidentally bridging phases with a jumper wire.

Most spectacular is a toss up. Most "up close and personal" is still bridging 480 V lugs with a screwdriver in an energized 50 HP starter bucket that was only protected by utility line fuses. Most spectacular in general is opening an out South States non-load break disconnect by hand, slowly. Not only is the linkage design on those things terrible (swing horizontal and then converts to a vertical motion, with lots and lots of problems with linkage timing), but arcing time is 100% controlled by the operator, and inexperienced ones destroy them. Fortunately I was still at least 15 feet away (overhead switchgear design) so the only danger was soiled underwear.

Early 70s, working as an electrician pulling wire into an energized panel with a metal fish tape. Impressive !!! Could not see or hear for several minutes. Experiencing and surviving an Arc Flash Blast gives you a better appreciation of NFPA 70 E.

Joe the reson I was able to avoid an injury was more of a fall from panic. I had workrd some 13800 volt switch gear and saw tracking live and know the sound. I avoided the blast by litterly a fraction of a second. My ears were ringing for a few hours after but i was out of the direct line of fire. I was approximatly 3 to 4 feet away and never saw the arc. ESWP!70E! cant say this loud enough.

In 1990, I was assisting an Egyptian engineering firm in a review of losses on various electrical distribution systems around the country. One possible source of losses was loose secondary connections on transformers. I was foolishly jiggling terminal connectors on the secondary panel of a large (maybe 1 MVA) 11 kV - 400 V pad mount transformer when I caused a phase-to-phase fault behind the panel where buses were very close together.

Knowing what I know now, I find it amazing that the arc flash was not much greater than it was and I was not burned (no PPE). The primary fuses had been replaced with wires and the wires burnt off. The feeder breaker at the 11 kV substation also tripped, causing an outage of a large part of the city of Mansoura.

You mean that the factory fuses were replaced with locally produced fuses of unknown calibration, right?

I've actually had a lot of small equipment (SOLA in particular) which appears to rely on wire diameter as an actual fuse link. "Real" fuses just intentionally add more thin sections and perhaps some silica sand or boric acid to accelerate the process.

In the system that I maintain now, we intentionally run smaller diameter jumpers to the lightning arrestors as a fuse link in case the lightning arrestor shorts to ground, and when you plot TCC's you can easily plot the cable limit right on the chart so this isn't just backwater technology. At first I turned my nose up at it but over time I've recognized the value of this very simple installation and I've even seen documentation recommending it in some overhead pole lightning arrester literature.

I’ve seen a piece of brass that was (don’t know the word: )shaped to the same dimensions as the fuse that was originally placed. I was told that the piece off brass was actually used as a ‘fuse’ because there were no similar size and rated fuses available at the time they needed to replace it. It was a decision by one worker and was definitely not considered good practice by the company. The supervisor used it as an example of unsafe conduct.

Mersen (as well as others I'm sure) has Shorting links of the same shape as fuses. Look for SL60 to SL800 (Class J or L), or for smaller sizes, CCNL30 or JNL30. I didn't check if they have some for other fuse class.
At least, those have the right outer tolerances to fit in the fuse holder

I have seen these as well. If you have a regenerative drive, you will have a fuse in the armature. These fuses are not needed in non-regenerative drives. Manufacturers would save manufacturing costs by producing only one power board for low-horsepower drives and use a brass plug as a jumper.

Of course. Every time I flip a switch or yank the cord on a running appliance.

In 1996 I was working with a senior Commissioning Engineer on a 400V 2000A Emergency Switchboard which utilised a full tier ASCO transfer switch for auto-changeover between normal and Emergency Gen supplies. We had successfully completed the pre-checks and were working the unit out performing several change-over cycles when the ASCO jammed. It was left in a state where one of the switches had opened (I can't remember which now) and the other failed to close. If anyone has worked on these types of switches then they will appreciate the mechanical (and electrical) interlocking between them. After defeating the door lock feature to take a look, we could see the point down the left hand side where the mechanism was jamming (both normal and emergency supplies were still on). In our wisdom, we decided we could use an insulated rod (a fiber glass broom handle if I remember correctly!) at it to free it up. As we were both peering into the left side of the unit and carrying out our well planned, fully risk assessed (not) activity, part of the mechanism disengaged from inside the unit and fell down, shorting out the lower of the incoming feeders. The ensuing arc flash caused, thinking back now, probably 2nd degree burns to my colleague's hands and forearms, and burned off all the hair on his arms, eyebrows and eyelids. As he was looking very near the incident location he also received severe 'arc eye' (which is a dreadful thing to have as others can no doubt testify). I was extremely lucky and just received temporary blindness from the flash and ringing ears for days afterwards.

In retrospect, I was young, a bit inexperienced, and a tad over-confident at the time - it was also the mid nineties and arc flash was not really considered back then like it is today. I have to admit that I unwittingly exposed myself to a few other incidents over my commissioning years, but just never really appreciated what could go wrong (and thankfully nothing else major did). I think what mitigated the effects of the arc in this case was the fact that it occurred behind the lower switch and so tended to spread sideways as opposed to directly towards us.

Actually, it was just a piece of small diameter wire.

We typically use such "slugs" to replace fuses in breaker control trip circuits. The idea being that it is better to risk damaging control wiring from a short circuit than risk having a trip circuit without power.

Quick answer is yes.

To set the scene and put your thinking in the correct frame of mind my accident occurred in 2001. Pretty much the beginning stages (for me) of Arc Flash awareness and PPE requirements. So for everyone who wants to point out the mistakes I made during this accident, remember it was 2001 not 2014. A lot has changed during those 14 years........

At the time of the accident I had over 25 years of experience, starting in 1974, working on medium voltage distribution systems. I often think as we get more experience working around energized equipment we become more complacent and really need to stop for an extra second and think before we act.


No serious injuries occurred during the accident, mostly because about 6 months prior we started wearing the FR welders jackets and face shields that I noticed the utility company workers would wear while performing switching events. As usual utility company safety programs are always ahead of general industry. There were a total of (4) people in the electric room that I was working in. The room was 30' X 30' with ample room to work, one set of double doors at the entrance to the room. Two of us were 15kv electrical service technicians, (1) facility electrician and (1) facility manager. At the time we were not implementing any boundaries, mostly because in 2001 we were not aware they existed. The task was to de-energize (1) of the (3) sets of cables located in an S&C 15kV switch while leaving the other (2) sets energized and in service. In order to perform this task (which I had performed many times) we would use the typical shock PPE equipment gloves/sleeves/hard hat/safety glasses. To pull/open the fuse we used a 6’ long insulated “Hot Stick�. At the end of the “Hot Stick� we installed a piece of equipment called a Loadbuster Tool. During the opening operation of the fuse the Loadbuster tool malfunctioned causing a very loud and very bright explosion. Arc Flash. The percussion wave from the explosion picked the two of us up, off of our feet, and we landed about 3’ back from the switch with a hard impact to the floor. We were very disoriented for about 10 seconds after the accident. We were fine, no injuries and no clothing fires, I believe for the fact we were wearing the welder jackets and face shields. The only injury that occurred during the event was to the supervisor, who was standing about 20’ away from the explosion. When he saw the flash and then heard the loud “BANG� he was blinded by the light and began to run out the door. The only injury was due to his lack of vision from the bright light, it temporally blinded him and he ran face first into the closed portion of the double door, not the open portion of the double door.