During a discussion elsewhere someone has suggested using a curly phone cable, with RJ11 connectors, to carry low-current 230V mains. This seems like madness to me. The proposer supports the argument with a copy of a phone cable spec that shows the cable is rated at 300V, but they forget the connector spec is rather less than that. Am I being an overly safety-conscious dinosaur?
230/2440VAC has peaks in excess of 240 x sqrt(2) = 340V
If both the cable and connector is truly rated at 300VAC then I guess it does conform, though I would insist on a note that it is not custom and practice to use such cable and connectors and not your decision to use them. Plus good labelling and correct fusing.
The connectors are not touch safe and would fall foul of the regulations for use in domestic environments. A lot of the old Bulgin plug and socket styles failed that, even though they were rated for mains.
Owain
I've found the specs for RJ11 and RJ45 now - the idea has been killed and common sense has returned (I hope)
you can buy curly mains cables
Why would they want to do that?
I believe it's a Bad Idea to do "surprising" things. Even if you can.
The old adage "just because you can, doesn't mean you should" seems particularly appropriate around potentially lethal electric currents.
I think a system could be mechanically designed such that fingers couldn't get to the connectors so conform.
Still a bad idea.
To save a very small amount of money - madness! Fortunately they've seen sense.
The real problem is the mis-use of a connector that is assumed to carry low voltages to carry a much higher voltage. People may damage equipment if they plug a 240 V RJ45 connector into a device that is expecting to see a few volts for Ethernet signals or for power-over-Ethernet. There is also the risk of the live pins, shrouded though they are by the plastic of the connector, touching a person - suppose you pick up the connector by the pin end and your finger end happens to compress enough to touch two pins with
240 V between them.One connector, one signal. That's why I don't like to see devices that have a 3.5 mm plug on the end of a cable from a PSU (I have a rechargeable razor like this). Not dangerous, but if you plugged that into an audio device with that socket, you'd probably damage it.
If you test on a shaver socket, or if you test with a mains distribution which is "higher than nominal", your insulation needs additional margin. Some mains can be 270V instead of 230V. Well outside the allowed value. The shaver transformer is good for higher voltages like that.
And... only a fool would do this on an *outside* install. I assume this is a power connection to the shed. Many cables are not UV rated and cannot be used (for long) in full sunlight.
Even proper cable, requires good installation technique by the person doing the install. The cable is not likely to be the only expense, on an outdoor install.
Paul
A two pin flexible mains cable socket fits nicely into a 3 pin XLR plug!
There was once an XLR mains connector, the LNE model, but this was discontinued long ago due to safety issues in domestic use.
I've built a unit for sending mains down a SMPTE hybrid fibre/copper cable, using the LEMO connector in common broadcast use. I do test for one of my units being on the other end of the cable before turning on the mains, as many broadcast cameras (£30K-ish) also use this cable.
Not just the BBC - they were fitted to Marconi cameras, but the pin allocation was different!
Even if the connector were rated 300v, it still wouldn't be adequate, because the RMS might well be 240v, but the peak is 336v.
Not only that, but the safety standards assume there will be spikes on top as well.
John
....and some charge amplifiers.
There is a huge amount to be said for 'leave it so a total noob can fix it', Stick to what is reasonable to expect.
Well I can think of a few things to consider... The wire cross section even on CAT5e is something like 0.17mm^2, with a max continuous current draw of 1.5A. So let's hope the thing on the end of the wire does not need overload protection.
DC resistance is 140 mOhms/m so say you had a 1m lead, connected to a supply point with say a loop impedance of 1.37Ohms (the max loop impedance for a B32 MCB), your prospective fault current would be:
230 / 1.51 = ~152AQuick check with the adiabatic equation:
s = sqrt(I^2 t) / k
If we use the normal k value for PVC, and fault clearing time requirement of 0.1 sec, then we get a minimum cross section of ~ 0.42mm.
So basically you have no fault protection - the cable could burst into flames or vaporise on a short circuit.
That is before you get to the problems of the normal RJ style connectors being mail and unshrouded - so a plug on both ends of the wire!
Not at all.
Am 08.03.2023 um 12:40:41 Uhr schrieb snipped-for-privacy@aolbin.com:
Do not do this. The contacts at the plugs and sockets don't have a protection against touching it. This is a health risk.
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