| General > General Technical Chat |
| The real reason why North America uses 120v instead of 240v. |
| << < (17/17) |
| Zero999:
120VDC is actually on the upper limit for SELV. It still needs basic insulation, but not the same precautions as AC of the same voltage.. I hate those site transformers. They're big and bulky and probably cause more injuries manual handling, than they save by reducing the shock risk. It's much safer to use 230V and an RCD. |
| james_s:
--- Quote from: Zero999 on November 30, 2022, 08:49:02 pm ---120VDC is actually on the upper limit for SELV. It still needs basic insulation, but not the same precautions as AC of the same voltage.. I hate those site transformers. They're big and bulky and probably cause more injuries manual handling, than they save by reducing the shock risk. It's much safer to use 230V and an RCD. --- End quote --- I suspect the transformers came along a lot sooner and the regulations just never changed, there's a lot of inertia in that sort of thing. It's a lot easier to make a new law than to get rid of an old one that isn't really needed anymore. |
| AVGresponding:
--- Quote from: Zero999 on November 30, 2022, 08:49:02 pm ---120VDC is actually on the upper limit for SELV. It still needs basic insulation, but not the same precautions as AC of the same voltage.. I hate those site transformers. They're big and bulky and probably cause more injuries manual handling, than they save by reducing the shock risk. It's much safer to use 230V and an RCD. --- End quote --- Yes, but we were talking about AC, not DC. The limit for AC is 50V. |
| Zero999:
--- Quote from: AVGresponding on November 30, 2022, 10:22:55 pm --- --- Quote from: Zero999 on November 30, 2022, 08:49:02 pm ---120VDC is actually on the upper limit for SELV. It still needs basic insulation, but not the same precautions as AC of the same voltage.. I hate those site transformers. They're big and bulky and probably cause more injuries manual handling, than they save by reducing the shock risk. It's much safer to use 230V and an RCD. --- End quote --- Yes, but we were talking about AC, not DC. The limit for AC is 50V. --- End quote --- I know. If you read Siwastaja's post, which I was responding to, you'll find he was using 120V DC. |
| AVGresponding:
--- Quote from: Zero999 on November 30, 2022, 10:30:07 pm --- --- Quote from: AVGresponding on November 30, 2022, 10:22:55 pm --- --- Quote from: Zero999 on November 30, 2022, 08:49:02 pm ---120VDC is actually on the upper limit for SELV. It still needs basic insulation, but not the same precautions as AC of the same voltage.. I hate those site transformers. They're big and bulky and probably cause more injuries manual handling, than they save by reducing the shock risk. It's much safer to use 230V and an RCD. --- End quote --- Yes, but we were talking about AC, not DC. The limit for AC is 50V. --- End quote --- I know. If you read Siwastaja's post, which I was responding to, you'll find he was using 120V DC. --- End quote --- Perhaps the confusion arose from their mistake regarding the nominal voltage of construction site equipment in the UK, and from the fact they are not clear about the actual voltage they are putting through the 110VAC appliance they are using. |
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