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Thread: Electrical Question

  1. #21
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    It is totally irresponsible to state "this or that" voltage will not harm you. All voltages should be considered potentially lethal. While this may be considered an extreme example, a 1.5 volt "D" cell battery if applied across the human heart with needle points could be fatal. I always wear leather gloves when working around an AC power source and always use an OSHA approved fiberglass ladder in lieu of the cheaper aluminum variety.
    Surely not everyone was Kung-fu fighting

  2. #22
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    I am sure there are going to be a few issues of what is 'practice' and 'regulation' in the various parts of the world - but in the UK the following should be observed:

    1. Anything (anything) connected to the household mains supply should be either double insulated (CLASS II) or have a safety earth (CLASS I). If an item of equipment has a safety earth (CLASS I) - and a metal case (or anything that is metal come to that) it should be bonded to the safety earth. There are regulations on the maximum resistance that can exist between the point of contact and the socket outlet. This is for your safety and should always (always) be connected.

    2. The safety earth should never have a 'large' current flowing in it from the incoming mains supply live or neutral. If the circuit has a modern form of protection - the protection device will specifically look for an imbalance in the live and neutral currents and trip the circuit should they exceed 30 mA (or so). A small leakage current is permitted to flow from the incoming mains supply to the safety earth.

    3. Anything else should be considered not a safety earth - but (say) a signal earth / screen for audio/visual equipment. These need to be considered in the overall design of an installation to avoid hum loops (circulating currents in the screens) etc. arising from imbalances in the differing mains supplies which the various items of equipment are connected to. These may be disconnected if desired (known as ground lifting). You can do this safely as the safety earth is always connected to protect the human from a malfunctioning piece of equipment.

    Have a healthy respect for the mains supply (be it 240V or 110V)...

    If battery powered - identify the stored energy source. A 3.6V cell could discharge tens of Amps (or more) into a short circuit very rapidly. There are a few cases of where head-mounted torches have burst into flames (notably due to counterfeit LiON batteries). I have seen a small toy helicopter burst into flames in the air - spectacular - but dangerous! No one was injured - but the fumes that were produced...

    That's my ten pence worth...

    Dave

  3. #23
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    Quote Originally Posted by Agent Orange View Post
    It is totally irresponsible to state "this or that" voltage will not harm you. All voltages should be considered potentially lethal. While this may be considered an extreme example, a 1.5 volt "D" cell battery if applied across the human heart with needle points could be fatal. I always wear leather gloves when working around an AC power source and always use an OSHA approved fiberglass ladder in lieu of the cheaper aluminum variety.
    Nothing will harm you if you carefully avoid it.

    I wouldn't wear leather gloves without proper insulating gloves underneath.

  4. #24
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    Quote Originally Posted by KC9UDX View Post

    I wouldn't wear leather gloves without proper insulating gloves underneath.
    I've never had a problem with leather gloves when dealing with household current.
    Surely not everyone was Kung-fu fighting

  5. #25
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    Quote Originally Posted by Agent Orange View Post
    I've never had a problem with leather gloves when dealing with household current.
    Can't say I've ever tried on household voltages, but the electric fence will punch right through them! Probably wouldn't work well even on 120VAC if they got damp.

  6. #26
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    Quote Originally Posted by glitch View Post
    Can't say I've ever tried on household voltages, but the electric fence will punch right through them! Probably wouldn't work well even on 120VAC if they got damp.
    Same with rubber gloves if they are wet or even damp. Common sense has to to kick in somewhere along the line.
    Surely not everyone was Kung-fu fighting

  7. #27
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    Quote Originally Posted by Agent Orange View Post
    Same with rubber gloves if they are wet or even damp. Common sense has to to kick in somewhere along the line.
    Not the actual electrician's glove liners I've got -- you wear them under a leather glove shell, they work fine damp/wet as long as there's no pinholes. Wouldn't be much use if they stopped working when you got sweaty!

  8. #28
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    And if you're going to wear gloves, those are the gloves to wear. With the leather protectors.

    Any other gloves are asking for trouble. But the bottom line is that you shouldn't be intentionally touching anything live with the gloves, either. They're only there in case you slip.

  9. #29
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    Quote Originally Posted by KC9UDX View Post
    Any other gloves are asking for trouble. But the bottom line is that you shouldn't be intentionally touching anything live with the gloves, either. They're only there in case you slip.
    Exactly this.

  10. #30
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    I'm only an armchair elechicken, but I'm pretty sure that neutral is supposed to be at equal potential to ground, not connected to it.
    Best case scenario, you trip a GFI if you try that. Worst case, your ground lug is now at mains potential, and all the hazards/potential damage that carries.
    My vintage systems: Tandy 1000 HX, Tandy 1000 RSX, and some random Pentium in a Hewitt Rand chassis...

    Some people keep a classic car in their garage. Some people keep vintage computers. The latter hobby is cheaper, usually takes less space, and is less likely to lead to a fatal accident.

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