Great video and I can finally put to rest an argument with another sparky in my company. He said yes to earthing, I said no. He even reported me to our manager over it! Now I can get my own back! Thanks guys!
I was once working on a suspended ceiling grid that was 'giving shocks' - turned out to be a rise in potential due to an accumulation of earth leakage of all the lovely shiny new LED fittings hanging in the grid
Comes back to the design and installation stage. Is the ceiling grid 3 floors up and attached to a wooden stud wall then no bonding needed. Is the ceiling grid ground floor and attached to a jumbo stud metal frame wall secured to the concrete reinforced floor? In the the case of the stud wall on the ground floor I'd recommend bonding it just to CYA as I've seen it produce a potential of 150v in the past dhe to faulty fitting and bad wiring etc, so yes in that situation I would personally bond it.
Yh I was gonna say, depending on building construction a suspended ceiling **could** be an extraneous conductive path. But again, the point being made I think was more just cause its a metal grid and part of the building doesn't immediately make it as such. A steel framed building with a false ceiling hung by catenary wires from the steel frame, yes likely has a good ground path. A more traditional brick and timber framed building with a suspended ceiling highly unlikely to be a path to ground. As Joe kinda says an implies, there of course are cases where you genuinely would need to do it, but the flat out 'you must earth the grid' is not the best approach as you can (as efixx say in other replies) be introducing a shock risk as opposed to reducing one.
Well, in theory correct, in reality I never saw a suspended ceiling where on top there was a ton of cable stuffed on it, even singles, connections not made in a junction box, just made in mammuths or Wagos or even tape and left there, then one pulls a cable, it gets loose, and touches the metal frame. If it's earthed the RCD trips (hopefully it's present and works) and you don't get a shock. Who install lighting it's not usually the electrician, since it's a simple job that the owner does, buys some LED panels online and installs them, and to join the cable to the one of the power supply they just use some Wagos and leave them in the ceiling, nobody will see them. Given these premises additional protection doesn't hurt. Like it doesn't earthing cable trays, because you know that somebody will sooner or later join two cables in a tray with just mammuths or tape.
You say the ceiling grid is often bonded in older installations - but these may have been installed to the 15th edition which was very heavy on bonding. Those who were practicing at that time still tend to bond more than is currently prescribed.
Should metal server racks (you know, the standalone / on castors 19" rackmount racks) in a plant room / server room / cupboard under the stairs be earthed? Assuming the contents of the rack unit is what you would expect, i.e. "consumer devices" with kettle leads, UPS devices, etc. and nothing wired direct to a wall? I bought one for our home network install, full height. It came with earthing kit. It just stands alone with a lot of network and speaker cable coming into it. There's a UPS at the bottom which is connected to a 13A mains outlet on the wall. Each device in the rack is connected to the UPS.
I did do it, including all the doors, but I don't think it would be so necessary... My UPS is earthed via the incoming line which also goes to the casing and connects via the rack ears to the rest of the cabinet. So are other peripherals in the rack that interconnect with that same UPS. Unless the rack ears would be painted or other parts that make contact but are not bare metal inside cavities or fittings, supplementary bonding might be a good measure. Also think of any earthing for incoming coaxial or RJ45 cabling connected to the patch panel that could introduce potential or spikes and destroy/weld equipment :)
Also - re your point about class 2 and class 1 lighting equipment. These points surround the possibility of a fault developing within the fitting. But I am guessing the most likely thing to happen that could make the grid system live is that the bloke who wired that equipment didn't do a screw terminal up enough, then a wire was dislodged later, pulling a conductor out of a junction box. Are we just saying "that shouldn't happen if the thing is connected properly"? Hope my question doesn't sound antagonistic, just interested.
@@tjwatts100 And if I'd said that to my foreman, when he asked why I was spending time bonding the grid, I know exactly where his steel toe-capped boots would have ended up. 😂
So many possibiltys and it can boil down to the "what if" scenario Joe lol..... and it can be hard to interpret the regs correctly sometimes (its metal and might touch something live on a full moon etc) but you explain well that with proper risk assesment and common sense sometimes...thats all thats needed to make the right decision....see the regs in simple form and not over confuse the issue....(this is the info that could safe you in court :) )...great vid and excuse my terrible grammer lol.
Depends on how the cables are run ie on tray or suspended with cable tie’s,and how fixtures are fitted,ie centre of the ceiling panel or to the frame ,
Didn't he cover that in the video by saying that cables shouldn't be run over the suspended ceiling? That routing and supporting cables properly is the right way to deal with it, and not by earth bonding the suspended metal structure?
Currently bonding a suspended ceiling in a brand new office block. Bonding water pipes, to the grid and grids to the trays. Time consuming but if it reduces any potential hazards. Maybe worth doing.
I can see the arguments for earthing such things, however there are also arguments against. In an instance of someone making direct contact with a live conductor (eg by putting a nail through it), earthed metalwork is more hazardous should that person simultaneously be making contact with it. Also, under an open PEN fault, earthed metalwork can go live, so in this instance it would be better if there was less of it.
The radiator could have 5 parallel paths . 1 from the heating element cpc, 1 from the boiler supply cpc, 1 from an immersion heater ( if cylinder fitted) and 2 from main bonding conductors . I think that's enough .
I work in a building that had the ceilings installed back in 2001 The amount of cables that have been strewn above the ceiling over the years actually get in the way when replacing the units ! Maybe earthing ceiling grids is a good idea ?
Chaps - I would be really interested if you would have the time to explore this further? On ceiling grids i've often measured hundreds of volts between the grid and MET. This is being caused by voltage induced by LED panels accumulating on the grid. Of course, there's no current to it - but it feels wrong leaving a grid like this? Bonding eliminates this. Ive tested this and you have to be careful - existing class 1 fittings resting on the grid for example will be providing a path to earth - but in an entirely isolated grid (IE tested it has no connection to MET) - ive often found induced voltage builds up with the addition of LED tiles. Seen this with Lumineux and JCC tiles at least.
seen this before as well, bonding stops the voltage? i had one that was bonded and when you touched the led panel screws (it was class2 ) and the earthed frame you got a really small shock???
Wow now we know.👍 But what I would like to know is 1) how was you up in that ceiling space with out the ceiling grid collapsing 😂2 it is formes the wall grid yet that wasn’t mentioned? . Fantastic video as always Joe 👍
On one of my first jobs the floor tiles caused us to load up with static as we walked. Everytime we touched the ceiling grid we discharged with a little blue spark. Now I'm wondering if the grid was earthed or not. 🤔😁
Think it should be seen as it was live on a job I was at. Leaning on it then touched conduit to complete the path. Was on steps and it sent me backwards. Was the swinging doors that broke my fall. Let’s face it there’s always cables laying on it.
That raceway has powered cables running through it the entire way and bas a better chance to become live for numerous reason and should be bonded to ground.
One of our guys was shocked by a live ceiling grid because some 🤡 had severed the cable to the lights and just left it there, so yes, earthing would help.
Used to be the norm to earth the main Ts modular fittings used to have earth tags on them that earthed the grid when placed, the question should be if the grid was covered with cables from multiple electrical circuits would it be unsafe to earth the grid, if you think so then don't become an electrician
Class 2 equipment is fine, but Class 1 and a forklift impact is a bigger risk?... I was at college in 1990's 16th edition, and told to bond every extranious conductive part, no harm doing that is there? apart from cost? but at what cost is a human life potentially worth?.. Common sense prevails as always. I have replaced those 600mm light fittings in offices with LED Class 2 equivilents, no prob.. but some of the older Fluorescent types have earth bonding and ive seen a few melted Ballasts in some... tricky! I would say yes bond if old fittings used, but not if replaced with class 2 fittings. lol..who knows?...
BS bollix, should be this, should be that ,etc. Sh1t happens, So putt an earth tag on the tray, grids, ducting, pipes etc. It takes a couple of minutes and just might save someone's life.
If it's not an extraneous conductive part, then there's possibly no compulsion. But if it does no harm, then why not? Lot of metalwork with cables dangling all over. If one cable gets damaged but sharp metal, rodents etc, the grid could end up live. I bonded my attic basket tray for the same reason. Too much following the Holy Book of Religion, too little thinking through the situation. No disrespect intended, that's s general criticism of the present times.
Same as happens to my copper gas pipe that runs all the way around the outside of my house. Except that is a risk as a person may contact the true ground and the pipe. That's rather less likely to be an issue in my wooden attic space where the only other extraneous metal objects (water pipes) are well bonded to the tray via the MET. Still a win I reckon and no real risk in my specific case, though you could argue your point if the tray runs through an area where contact with it and true ground is likely, like outdoors, or in a room with a concrete floor, especially one that may become wet. This does rather highlight TN-C-S as an inferior system to TN-S: in principle the utility company should have adequate MEN provision, but it will never be as good. Just cheaper... Perhaps this is an argument for adding earth rods/etc to every TN-C-S MET to improve the odds? I have one, but that's because I have a genny transfer switch too.
