mains power safety precautions - Page 1
Forum section: electronics / beginners

author: beginner
author_rank: Contributor
timestamp: June 15, 2014, 08:56:49 am
content: I've been avoiding working with mains power for my projects, just using batteries or external DC converters to keep things safe and easy. My current project would work out best using an IEC C8 inlet, which would be wired to an AC / DC converter housed inside the project. I only need to run a couple of AC carrying wires from the inlet to the converter , but aside from not wiring these with it plugged into the wall and ensuring these wires are secure, are there any other considerations for long term safety? connections would be solder tab and screw terminal. Thanks guys

author: Psi
author_rank: Super Contributor
timestamp: June 15, 2014, 09:25:46 am
content: - Use mains rated cable- Good insulation over all exposed mains conductors. (eg rubber boots, heatshink etc.. over terminals)- Cable retention to keep mains wires all neat and out of the way, you don't want mains cables (or any cable) flexing repeatedly- Make sure you do the appliance earthing correctly.- Keep the mains wiring in a section away from everything else, not only for 50/60hz noise issues but so you don't have to go anywhere near it to work on the low voltage side.- Have a mains fuse (if not built into the socket)

author: tautech
author_rank: Super Contributor
timestamp: June 15, 2014, 09:29:47 am
content: +1Correct color coding for mains cable, these days, brown for phase, blue for neutral.

author: Psi
author_rank: Super Contributor
timestamp: June 15, 2014, 09:33:12 am
content: heh, i knew i was forgetting something important.But in his case the IEC C8 inlet connector is not polarized, so P and N can be any way around. I assume his device is double insulated?I would use brown wire for both connections.hm.. I'm not sure how non polarized mains products handle the fuses, since you don't know which side the fuse will end up in.

author: GreyWoolfe
author_rank: Unknown
timestamp: June 15, 2014, 11:39:16 am
content: If it is all in a case, don't forget strain relief on the mains wires.

author: rob77
author_rank: Super Contributor
timestamp: June 15, 2014, 12:46:50 pm
content: Quote from: Psi on June 15, 2014, 09:33:12 ami think that's exactly the reason for double insulationif the fuse is blown and it was in the neutral path, the device's guts will be live.

author: digsys
author_rank: Unknown
timestamp: June 15, 2014, 02:05:24 pm
content: It is also good (common) practice to -- Heatshrink over the soldered joints.- cable tie all 3 (2) wires close to the socket, so that IF any 1 of the wires ever does come loose, it can't reach / touch a neighbour ' frame.- a layer of 240v insulation eg nomex etc in between the wires and frame / surrounds.1+2 are easy to do. +3 is a must, if others will use the device / it is transported a lot.

author: beginner
author_rank: Contributor
timestamp: June 15, 2014, 04:25:12 pm
content: Thanks for all the pointers, looks like I have a little more research to do before going ahead with this, specifically into use of IEC C8. Any suggestions on connector types which may be simpler to work with first time around?

author: Psi
author_rank: Super Contributor
timestamp: June 15, 2014, 07:04:00 pm
content: You can get CEE22 style sockets with a built in fuse holder. It sits in a little tray that comes out.At least that means you dont need to worry about mounting/wiring a fuse yourself.