Good day folks. Recently my company has, in a kinda-sorta-way, nominated me to join the "security systems team" which involves going to various sites to install alarm systems and CCTV cameras...not the best of positions, since I've gravitated pretty far away from my beloved laptop and electronics repair, but at least the pay is adequate (enough....for now) and I'll definitely be moving back to those once my boss decides it's the right time, but I digress.
The reason I'm asking about how mains grounding works is because more often than not, I have to connect up the alarm panel's mains supply directly to a distribution box rather than an outlet with a simple plug-socket and this involves playing electrician and playing around live wires to a pretty good extent....which I don't really mind, it's fun as sh!t for some reason Feel the danger !
Anyway, having opened up a couple of distribution panels so far, some of which were rather old and messy as you can see in the example pictures below (some even going as far as still using ceramic cartridge fuses, even blown ones at that, with pieces of wire jammed in them to revive them!), I had a bit of trouble properly identifying the neutral from GND (earth), or rather couldn't tell which was the safest way to connect these up.
Some had a flat earthing bar coming into the box, tied to the metal chassis which holds all the fuses/MCBs and all individual earth wires running to the outlets were tied to this, which was the easiest and IMO safest thing to work on, with three separate connections: L to L, N to N and E to E - simple, consistent, perfect (panel in the first picture was like this, despite being a mess in terms of everything else, including those "reused" fuses I mentioned).
Then there were others where the chassis had the N wire tied to it, making things a bit......confusing. I know it's "neutral", but shouldn't this be separate from E ? For this reason, I hesitated a bit when touching the metal case of the alarm system after the first powerup When I first encountered this setup at one of my sites, I didn't even connect the GND wire for the panel, thinking it'd result in an unsafe setup if the wires were somehow swapped and the chassis became fully hot. Panel in the second picture had this "combined" setup - notice the long green wire leading into the white box of MCB: this tied all the neutral wires to the metal chassis and that earth bar which was somewhere in the bottom-left of the panel. I was actually planning on removing this piece of wire when I did the install there to make it like the first one.
This last one I did today was the most interesting so far: a 380v three phase panel, because the building also has a small elevator. Of course, I didn't quite care about that, since it still broke the phases apart into the more manageable MCBs we're all used to as you can see in the third pic after the BIG breaker and ceramic fuses which I couldn't quite figure out what they do, especially since it had some sort of weird two-meter configuration, presumably sharing the costs with another company or some junk....This too had earth tied to neutral. Electricians might spot this, but you can see all those MCBs in the picture, despite being on separate phases, all end up with a small common blue piece of wire back to the earth bus bar at the bottom of the box where the green wires are, which is presumably the star point of the three phases. This again didn't seem particularly safe TO ME, though in the back of my head I was certain nothing would happen, since it wouldn't be done otherwise and would pose a hazard for ALL earthed equipment in this building like washing machines and fridges, so this time I DID wire my alarm's chassis to that common N/E bar (white wire coming in through the top of the MCB box and snaking around the right, near the screw post and back up to the top of the "tripped" MCB).
Wikipedia was very helpful in clearing up some of the mystery that to this point I always thought was some idiot's unsafe idea of tying E to N willy nilly, but still: any electricians in the house ? What are some of the dangers and precautions I faced here ?
The reason I'm asking about how mains grounding works is because more often than not, I have to connect up the alarm panel's mains supply directly to a distribution box rather than an outlet with a simple plug-socket and this involves playing electrician and playing around live wires to a pretty good extent....which I don't really mind, it's fun as sh!t for some reason Feel the danger !
Anyway, having opened up a couple of distribution panels so far, some of which were rather old and messy as you can see in the example pictures below (some even going as far as still using ceramic cartridge fuses, even blown ones at that, with pieces of wire jammed in them to revive them!), I had a bit of trouble properly identifying the neutral from GND (earth), or rather couldn't tell which was the safest way to connect these up.
Some had a flat earthing bar coming into the box, tied to the metal chassis which holds all the fuses/MCBs and all individual earth wires running to the outlets were tied to this, which was the easiest and IMO safest thing to work on, with three separate connections: L to L, N to N and E to E - simple, consistent, perfect (panel in the first picture was like this, despite being a mess in terms of everything else, including those "reused" fuses I mentioned).
Then there were others where the chassis had the N wire tied to it, making things a bit......confusing. I know it's "neutral", but shouldn't this be separate from E ? For this reason, I hesitated a bit when touching the metal case of the alarm system after the first powerup When I first encountered this setup at one of my sites, I didn't even connect the GND wire for the panel, thinking it'd result in an unsafe setup if the wires were somehow swapped and the chassis became fully hot. Panel in the second picture had this "combined" setup - notice the long green wire leading into the white box of MCB: this tied all the neutral wires to the metal chassis and that earth bar which was somewhere in the bottom-left of the panel. I was actually planning on removing this piece of wire when I did the install there to make it like the first one.
This last one I did today was the most interesting so far: a 380v three phase panel, because the building also has a small elevator. Of course, I didn't quite care about that, since it still broke the phases apart into the more manageable MCBs we're all used to as you can see in the third pic after the BIG breaker and ceramic fuses which I couldn't quite figure out what they do, especially since it had some sort of weird two-meter configuration, presumably sharing the costs with another company or some junk....This too had earth tied to neutral. Electricians might spot this, but you can see all those MCBs in the picture, despite being on separate phases, all end up with a small common blue piece of wire back to the earth bus bar at the bottom of the box where the green wires are, which is presumably the star point of the three phases. This again didn't seem particularly safe TO ME, though in the back of my head I was certain nothing would happen, since it wouldn't be done otherwise and would pose a hazard for ALL earthed equipment in this building like washing machines and fridges, so this time I DID wire my alarm's chassis to that common N/E bar (white wire coming in through the top of the MCB box and snaking around the right, near the screw post and back up to the top of the "tripped" MCB).
Wikipedia was very helpful in clearing up some of the mystery that to this point I always thought was some idiot's unsafe idea of tying E to N willy nilly, but still: any electricians in the house ? What are some of the dangers and precautions I faced here ?
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