| Electronics > Repair |
| Question about voltage in U.S. house built in 1890 |
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| CaptDon:
Conduit as a ground conductor or current carrying conductor is outlawed in the U.S. for good reason. Apparently in the O.P.'s house the wiring through the walls is mostly two conductor. As a matter of convenience many of the two prong outlets were replaced with grounded outlets but with no actual ground wire available. This is very typical of 'homeowner upgrades' when they have no clue about safety. I personally got thrown to the ground at a public swimming pool. I got out of the pool and went to play the jukebox standing on wet concrete. An inspection was made and it was a grounded outlet connected with no ground. The failure was internal to the jukebox putting the hot conductor directly to the metal frame of the jukebox. The owners of the pool said "We checked and didn't feel any shock although we had complaints". (They were obviously wearing shoes when they 'checked for shock'). |
| bdunham7:
--- Quote from: CaptDon on May 15, 2024, 01:20:14 pm ---Conduit as a ground conductor or current carrying conductor is outlawed in the U.S. for good reason. --- End quote --- Do you have a cite for that? I don't think it is prohibited, at least not in the general case. It certainly was acceptable and common in the past, no more than a few decades ago. Receptacles used in metal boxes still have a feature where they 'self ground' to the box without any wires needed, although everyone bonds them with a wire and a clip nowadays. It is totally plausible that whoever installed the current system in the OP's house didn't use any ground wires at all except for that one large one going to the meter box and that it passed an inspection that way. |
| themadhippy:
--- Quote ---Conduit as a ground conductor or current carrying conductor is outlawed --- End quote --- many would have you believe thats also the case in the uk. Out of curiosity how is american conduit joined together,anything ive seem on line seems to be a clamp type arrangement,same for termination into a box? Over here metal conduit is threaded and screwed into a coupler to join lengths ,for boxes we use a brass bush and coupler |
| bdunham7:
--- Quote from: themadhippy on May 15, 2024, 03:07:15 pm ---Out of curiosity how is american conduit joined together,anything ive seem on line seems to be a clamp type arrangement,same for termination into a box? Over here metal conduit is threaded and screwed into a coupler to join lengths ,for boxes we use a brass bush and coupler --- End quote --- There are two types of "conduit", EMT and rigid. EMT is lighter and uses various devices such as single-screw retainers and compression clamps while rigid has pipe threads and couplers as the basic connection method. https://www.eaton.com/content/dam/eaton/products/conduit-cable-and-wire-management/crouse-hinds/catalog-pages/crouse-hinds-connectors-couplings-emt-catalog-page.pdf |
| niemand:
--- Quote from: BlownUpCapacitor on May 14, 2024, 06:20:02 pm ---Use a DMM to measure the potential of those boxes to ground. Should be near zero or under 10v. I wouldn't go touching those boxes if they are at an elevated voltage. --- End quote --- For ground, I used my neighbor's grounding rod: Probing the screw at the bottom of the panel... ...I got less than 0.5 V and a duty cycle of 300 Hz: Probing the inside of the box... ...I got less than 0.1 V and a duty cycle of 60 Hz: Compare with probing the plumbing pipe in the bathroom using the ground from the GFCI outlet (like I did yesterday in my reply #17): I got 0.005 V and a duty cycle of 60 Hz. |
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