Whilst doing some additions due to building works, came across these 2 pendants. (Photo's a bit fuzzy as taken with my phone camera).
Who needs a neutral?
- Thread starter vera121
- Start date
I take it there was no RCD
It is quite difficult to understand the 'mindset' of a person who does something like that. Maybe we have to blame 'harmonised colours' to some extent - with someone thinking that blue was closer to G/Y than to black!
Kind Regards, John
i assume its not actually earth and someone has used the uninsulated wire for a netural connection.
Doubt it, it will more likely be someone not knowing what they are doing and trying every combination to get it to work.
In a TN system the earth (CPC) and neutral connect to the same place either back at the transformer or at the cutout so it will work (providing there is no RCD protection), it just isn't safe nor legal.
In a TN system the earth (CPC) and neutral connect to the same place either back at the transformer or at the cutout so it will work (providing there is no RCD protection), it just isn't safe nor legal.
You think so? If so, what would they have been using the black insulated ones for - and why would they have sleeved their neutral with G/Y? ... seems fairly unlikely to me.
Kind Regards, John
Yes, no RCD protection, just a DIYer having a go!
Even with TT, particularly with parallel paths to earth via main bonding, at least a few of those would probably work (at least with incandescent lamps) without people noticing too much reduced brightness - but, of course, with TT there certainly ought to be an RCD - so it shouldn't work!
Kind Regards, John
Depends on the rating of RCD, load of connected lamps etc
True, but I was talking of 'at least a few', and incandescent lamps. Assuming to other L-E leaks, a 100mA RCD (which I guess is, traditionally, what one would be most likely to find in a TT installation) would obviously allow up to 23W total of lamps (connected L-E) without tripping, and a 300mA one up to 69W total.
Kind Regards, John
Sure, the sums get complicated, and require data (on voltage/resistance relationship for lamps) that I don't have readily available. However, taking my TT electrode as an example (generally around 75ΩI don't even think you'd get that, given the cold resistance of a lamp is lower than with it hot. Then the rod resistance makes the maths too difficult to be bothered to do
, that would probably have little impact at the loads we're talking about. A lamp which took 100mA at 230V (i.e. 23W) would have an impedance (hot, with 230V) of 2,300Ω. Hence, if it's impedance remained essentially unchanged, it would still get about 222.7V if the return path were just via my TT rod. I therefore doubt that the voltage it did get, given the lower resistance at the lower voltage, would be a lot under 220V.Of course, in many/most TT installations, the rod resistance is, in practice, pretty irrelevant because of parallel paths to earth. Although my rod is usually around 75Ω, Ze is actually invariably less than 0.5Ω with bonding connected.
Kind Regards, John
It ain't going to be 'cold', or anything approaching cold, with something approaching 220V (or anything like that) across it. I'll see if I can find some data.
Kind Regards, John
I did a job where a light had had N & E reversed at a hidden joint box.
It was a TT supply with no RCD and the light was working fine.
It was a nightmare to put right.
It was a TT supply with no RCD and the light was working fine.
It was a nightmare to put right.
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