ECN Forum Forums General Topics of the Trade General Discussion Area Live Power

Look at these images, write them down, and always follow them to be sure and stay safe!
https://www.electrical-contractor.net/jt/P1110004.JPG
https://www.electrical-contractor.net/jt/P1110005.JPG

Courtesy: Dupont Corp.

PS: The safest way is to work on equipment with the power off!

I don't do much commercial work,but the few commercial customers I do have,understand that I don't do much live work.

I'm fortunate in the fact that I don't need to do it to keep my job,or to make it convienient for someone to make a few bucks while I work hot.

I do some residential troubleshooting hot,but less and less of it as the years go by.

Russell

As a non professional with zero formal training, I 'work hot' every single day, safely and without incident.

The reason is that my 'working hot' is limited to attaching and disconnecting cord connected appliances. Okay, something of a joke, because plugging in a toaster is not what a professional electrician is thinking of when someone says 'working hot'. But it really is relevant: working hot is different for each job considered, and the risks involved depend upon just what hardware is being dealt with, just what work needs to be done, just what skill level is available, just what safety hardware is in use, etc.

Just try plugging in an appliance with a bolted short. You will quickly realize that simply plugging something is not entirely safe, even though it is considered acceptable for non electricians to use plugs and receptacles. Carefully considered and planned, with appropriate safety gear, I believe that 'working hot' could be as safe as plugging something in.

On the other hand, it seems to me that in many commercial situations, 'working hot' is required only because of scrimping on necessary protection hardware. If that computer over there _needs_ to be up 24 by 7, and you _cannot_ shut it down, then it should be on redundant circuits with redundant power supplies, and the entire computer itself should have an off site fall over backup so that can take over the processing load in an emergency. If this computer doesn't have the necessary backup, then someone clearly doesn't think that it really is worth keeping on 24 by 7. If the computer _does_ have this necessary backup, then you can schedule down time for the circuit and make the repairs without 'working hot'.

In other words, it seems to me that 'working hot' is often necessitated by someone trying to save a few dollars, and this attitude is the same one that prevents spending more for the additional precautions that working hot should require. If professional electricians simply quoted higher rates for working hot, then I'd bet there would be less demand for the special service. Instead of saying 'I won't work hot.', you might say 'If I work the circuit cold, the job will cost $200 and take 2 hours. If I work the circuit hot, the job will cost $500 and take 5 hours.' In this situation, I would bet that most of the people demanding that you work hot would start figuring out how to shut down equipment quickly

It does come down to the rather scary calculus of dollars spent versus lives lost, and IMHO you can't simply say that no price is too high to save a single life. The reason is that every resource that goes into protecting life in one way (say preventing electrocution) is a resource that doesn't get used elsewhere. Sometimes this means that we don't spend money protecting life because we want to spend that money lining some rich dude's pocket (a bad outcome, IMHO), and other times this means that we don't spend money protecting life in one case because we can spend that money protecting more lives elsewhere ( a good outcome, IMHO). I think that the car safety analogy mentioned above is a really good one to think about. If you could insure that the risk for a given job is lower than the risk of driving your car to the job, would you 'work hot'? How about driving a motorcycle to the job? What about if it were as safe as hang-gliding to the job? Alas, the numbers aren't out there to even hazard a guess at the relative risks

-Jon

Jon I am glad you got what I was rambling about.

I am not advocating unsafe work practices.

I would just like to know the relative risks.

This statement goes along well with what is in my mind.

There are many things that non professionals deal with on a daily basis that I as a professional can not.

That J Box picture I posted above should be safe to mess with as the conductors are supposed to be all insulated, just like plugging in power cords is considered safe because there should not be shorts.

I have changed my thinking greatly already, I work much safer now than ever before.

I was taught to work hot by a guy that had been taught to work hot and so on.

Now with formal safety training I have learned more about what can happen.

That said I still think some of the rules are a little extreme.

If I think to much about vehicle accidents I will be wearing a crash helmet and NHL goalie pads, just to drive to work.

Bob

The idea of working hot or killing the power, may be more of a judgement call.
Let's say you are changing a recpt. to change it hot when not required could be a bad call. When troubleshooting live circuits, you have to consider the conditions, such as working space, dangers of accidential contact, and condition of equipment you are working on, all these things require good judgement and an established skill set in your field. An experienced electrician, should know when conditions to work hot, are not acceptable.
The risk level that one will take is established with, level of skill and the way they judge the conditions.
Bob, showed a box in his post, I would not work that box hot, however this does not make his way of working wrong or my way right, I think if you polled a number of EC's you would find each had a different aproach on how they would work that box.

I feel that much of the modern safety legislation tries to override common sense by imposing a rigid set of rules to all situations.

Would I open a live panel to reach in and take voltage readings, so long as I can do so safely? Yes, I do it regularly, and experience teaches me what situations can be considered safe to do this.

Would I work the panel live if to get at the parts I needed to reach meant sliding my bare arm down the side of an enclosure only a couple of inches away from 415V busbars? No, because to me that becomes an unacceptable risk.

To impose a rigid rule that nothing must ever be worked live ignores those cases where it is the only practical way to troubleshoot a problem or to adjust some piece of equipment. That doesn't mean that I'll do something live if in my experience to do so would put me at unnecessary risk.

In my telecoms work I've regularly adjusted transmitters and other equipment containing high voltage supplies live. There's no other way to do the job, but for equipment which needs to be adjusted live, it should be designed in such a way that access is possible without risk to the operator (or perhaps I should say without undue risk, since everything we do in our lives carries a certain element of risk).