I'd recently been given an EMF meter and when I turned it on, the EMF around most of the house was around 15 head height. If I'm downstairs and raise it to the ceiling it's well above 100 and the same upstairs putting it towards the floor. Now this is a bit worrying as we've been living in this house for the last 16 years but not only that I've recently had kids and where my 3-year-old sleep's he's being pummelled with 20 gauss.
I'd turned all power off at the fuse and proceeded to remove fuses to narrow down which circuit was causing the high levels. My first thought was it must be the light circuit as it was the roof and floors that had the highest readings but it turns out it was the outlet circuit that's causing the issue.
I've done some research and found that a neutral wire returning via a different live wire can cause this to happen and is in fact quite a common issue.
So my question is where and how is it best to start to find where that neutral wire has gone astray?
I'm currently in the process of getting our old fuse box replaced with a newer version. So thought now would probably be a good time to look into getting this sorted. Thanks for your help in advance.
Best Answer
That's a big job. I had to sort out a bunch of wiring in an old factory which had a lot of neutral problems. I shut off service to the building and, at the panel, "pulled off" one hot and neutral off each circuit and did a series of diagnostics, checking for resistance between it and the rest of the neutrals, and resistance between the hot and neutral, and hot and other neutrals - alternating whether night-lights were plugged in or not. If anything seemed out of the ordinary I followed it to the next junction box and carefully troubleshot, and the next, and so on until it tested clean. (this was a real mess as many circuits were MWBCs.) I don't recommend this, but I also had a 120v extension cord coming from another building, and connected the pulled-off circuit to that, and sniffed for voltage being anywhere it should not. I would not recommend doing that with 230v, that stuff bites hard.
It can help to install a GFCI breaker (UK: RCD) in your panel, as they will trip if there is any cross-neutral activity between circuits. You can move it around from circuit to circuit. Likewise you can put GFCI outlets on any point in the branch circuit, which will protect everything downstream. In fact, many service panels have an outlet right next to the panel, and you could install a GFCI in there, attach a hot and neutral wire to the "load" side, and use that to test each circuit in turn. I wish I had thought of that in hindsight!