I suspect that this may not be the place to answer my question, and if it isn't I apologise now, but I couldn't find any more appropriate group.
I want to board up the loft floor to create some storage space, but in addition to the upper-floor lighting circuits, I have found a network of rusting, metal conduits with old electrical wiring inside (three single cables, not sheathed). BTW, the house is circa 1920s. I have found four ends to the wiring, where it has just been cut (not terminated) and the wiring left exposed. I want to rip the whole lot out, but obviously want to individually check each run to ensure that it isn't live before I do so. What is the best, economic method for me to do this? Can I get a simple tester to check live cables (even if they are not under load)?
Your best advice is to get an electrician to look at it.
Electrical engineering newsgroups are just that, for discussing electrical engineering. Any advice you get here could be flawed because no-one knows whether you've told them all the facts, and giving advice with only half the facts is just plain hazardous.
best advice we could give you is for you to contact a competent electrician. Nothing we could tell you would allow a complete novice to safely test or remove these circuits.
The device at the link below is a very useful tool, but if you rely on such a tool alone to protect you from contact with a live electrical circuit at some point you may be in for a possibly lethal surprise.
Devices such as this do malfunction, have dead batteries, etc. Most of the electricians I see using non-contact voltage probes have established routines they use each time before using one to declare a circuit safe. With many that includes an additional meter. Interestingly enough they can indicate voltage where lethal current isn't present.
Most of the people frequenting this group have, or should have the common sense and knowledge to use a non-contact voltage probe safely, but I cringe at the thought of them in the hand of an inexperienced person.
Louis--
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| The device at the link below is a very useful tool, but if you rely on such | a tool alone to protect you from contact with a live electrical circuit at | some point you may be in for a possibly lethal surprise. | | Devices such as this do malfunction, have dead batteries, etc. Most of the | electricians I see using non-contact voltage probes have established | routines they use each time before using one to declare a circuit safe. With | many that includes an additional meter. Interestingly enough they can | indicate voltage where lethal current isn't present. | | Most of the people frequenting this group have, or should have the common | sense and knowledge to use a non-contact voltage probe safely, but I cringe | at the thought of them in the hand of an inexperienced person.
I always test it two ways every time I use it. First, it does give one beep and flash when turned on (the momentary contact switch). Then I actually find a live wire to test it with somewhere around to see it is in fact working. I don't want false negatives.
Thanks for the pointers. I suspected that many would suggest getting an electrician to do this for me, which is probably the best advice, but I had rather hoped that there would be a simple way for me to check it out myself, especially given that the old wiring is _almost_ certainly not live. However, I suppose I should bow to conventional wisdom and get the 'phone book out...
That is why we push them in a known hot outlet before we test with them. The OP has what to me sounds like abandoned conduits. This little tester will most definitely tell him if the conduits are live or not. The circuit is either on or off. Yes I would trust it. In the past I did weekly
You've hit the precise problem, "sounds like". I believe it's near impossible to evaluate someone's situation from an EMAIL posting. It's additionally difficult when the posts requesting help or information lack even the basic information to paint an outline of a picture. The "abandoned" conduits could in fact contain some working circuits with an extention into the area in question. A "sleeping" circuit can be cut, bare and open, or otherwise appear to be unused. These "sleeping" circuits could take the form of a switched hot (you just know that someone will switch it at the precise moment you are up in the attic tied up in it [hmmm.... I wonder what this switch does?]), switched via a photo cell, a neutral coming live after its normal path back to the panel is interrupted, etc.
Even if one doesn't get hurt in the process, arbitraily removing the wiring before varifying it is truly abandoned could leave systems that you might be unaware of in an inoperative state.
See the above paragraph.
Each person has to assess their comfort zone individually. I have investigated numerous instances of electrocution, and electrical burns where the person in question "trusted" a circumstance where it might not have been the best choice to have made. I've even heard, "but I've done it hundreds of times before without any problems" during the investigations.
I would advise the original poster to do the work himself if he has the skills, and knowledge to accomplish the task safely, but it could be in his best interest to at least have an experienced person evaluate the situation, and possible offer suggestions on how to best accomplish what he's after.
Louis--
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Today's ad in the local paper lists a Greenlee Non-contact Voltage Probe for $13. From the ad it appears to be one of the better quality models.
Wrong is such an all encompassing word. Who am I, or anyone else for that matter, to pronounce you wrong. The posts/information I have noticed from you strike me as being from a literate, and knowledgeable individual. I don't really know you, or first hand the facts surrounding the OP's situation. While I wouldn't presume to classify you as wrong it always makes me a bit nervous when offering advice on potentially hazardous subjects where the person posting the question appears to be unsure of the basics. Advising long distance always presents the hazard of the information being misunderstood completely or in part, and the advisee electing to not follow certain portions of the advise they may in their estimation deem to be in excess or unnecessary. It's just so easy to get "crosswise" with an electrical project where the safe return from an unintentional error may not be possible.
That said I do believe that many individuals posses the intelligence and understanding to accomplish doing their own electrical work, or are capable of learning. Some with no assistance needed. Others might need help/hand holding of various levels. Some might prompt an evacuation of entire neighborhoods simply by considering picking up a tool. :-] I suspect that the OP would be the best judge of the level of assistance/advise he needs. I do believe however, that people offering electrical advice have at least some burden to suggest bringing in knowledgeable assistance where it's painfully apparent the person seeking assistance might be in over their head, or lack the understanding to proceed safely.
Louis--************************************** Remove the two fish in address to respond
The tester gives a positive indication that the circuit is live. It does not give a positive indication that the circuit is dead.
The beeping tells you to treat the circuit as live. The lack of beeping does not tell you to treat the circuit as dead.
The op is clearly looking for a tester to tell him "it is safe for you to work on this circuit, because it is dead". That's not how he worded his question - but it is clear that is what he has in mind. The Greenlee tester can tell him it is not safe for him to work on the circuit - but it cannot tell him it is safe.
Exactly right. The Greenlee tester is handy for finding hot wires in a diagnostic mode but it is dangerous as a safety tester. A contact neon tester or a wiggy is better. When I am absolutely sure it is dead I am still going to short it out before I touch it.
On 02 Sep 2004 04:31:42 GMT Greg wrote: |>The beeping tells you to treat the circuit as live. |>The lack of beeping does not tell you to treat the circuit as dead. |>
| | Exactly right. The Greenlee tester is handy for finding hot wires in a | diagnostic mode but it is dangerous as a safety tester. A contact neon tester | or a wiggy is better. When I am absolutely sure it is dead I am still going to | short it out before I touch it.
And do you look the other way as you make the shorting contact, just in case, to avoid retina damage?
My all plastec, Crews, safety glasses are UV-a, UV-b and IR compliant. (my sunglasses that are hanging around my neck on a "croakie" all the time). I short out the wire after I am "sure" it is dead and I have still had sparks enough times that I take precautions. I don't trust anything.
I have always found the best method for finding out if something is live is to place your foot in a galvanized bucket of water in a puddle and grab all wires simultainiously. This way you dont have to buy a $20 tester that may give you a false reading.
Agreed. The three step procedure you've listed is a sound practice, but two possibilities still concern me.
In the hands of an inexperienced person it still could be inadequate. It doesn't address the possibility of checking a conductor that might be switched, or under automatic control. It also doesn't account for this same inexperienced individual placing the probes on an insulated surface that appears to be part of the conductor (I watched an engineer do just that once, and then begin to disassemble what was in actuality a live bus section).
Second, it is possible for a non-contact voltage probe to lie, or misrepresent voltage as being present. Admittedly the lying is possibly in your favor, but still confusing to the unknowledgeable person. Wires, and other conductors that are under the inductive influence of a live current carrying conductor can induce a low potential voltage signal in surrounding conductors not connected to a live source. This signal will report as live on non-contact, and even high input non-loading meters.
The three step procedure you suggest is sound in the hands of an experienced person, but I would still counsel the inexperienced to at least consult an electrician/engineer before engaging in activities that could end up being a one way dead end street.
Louis--
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I agree completely. I wasn't promoting that an amateur do this at all! I saw several posts that mentioned verifying the tester before making the measurement, and I wanted to emphasize that you need to verify it again after making the measurement, to be sure it didn't just die coincidently.
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