in this q&&a video, we're going to answer the question do I need to bond a suspended ceiling
grid, this question relates to a video we made on the Tuffflex Tile from Marshall Tufflex which
is a product we absolutely love because it reduces the need to chop up plywood on site to go behind
ceiling tiles when mounting recessed lights and the like so do please go and check out that video
after watching this one but let's think about this question you do see it from time to time
don't you especially on older installations where a connection has been made from the
earth terminal of a laying light fitting to the grid of the suspended ceiling and sometimes it's
taken even further and the L bracket around the side has a green and yellow link from one piece
to another in the corner but is any of this necessary well there's two types of conductive
material in the building that may need connecting to the main earthing terminal of an installation
these being exposed and extraneous conductive parts and bs7671 defines them as follows an
exposed conductive part is a conductive part of equipment which can be touched and which is not
normally live but which can become live under fault conditions the simple way to remember
it is that this is a metal component which is actually part of the electrical installation
and which can become live under fault conditions so things like metal casings of single insulated
equipment in containment like conduit or trunking although not cable tray as we've explained in
another video and the definition of an extraneous conductive part is a part liable to introduce a
potential generally Earth potential and not forming part of the electrical installation
so again think of this as being something extra to or outside the electrical installation and which
could give a good connection to the literal Earth that we walk around on this could include metal
pipes for water or gas or oil as long as it does in fact introduce an earth potential again check
out the video we've made showing why you may not need to bond as many pipes as you think you do
so the question now is does that sealing grid fall into either of these categories well is it
part of the electrical installation absolutely not you may come across installations where the
cables have been thrown over the grid and it's seen as some kind of built-in Cable support it
should absolutely not be used for this purpose if cabling has been installed like this the solution
is not to Earth the grid but rather to provide proper support for the cables so it's not part
of the electrical installation therefore it's not an exposed conductive part so you wouldn't
Earth it for this reason but is it an extraneous conductive part well remember that to qualify as
an extraneous conductive part it has to introduce a potential generally Earth potential into the
property which means that it has to have really good contact with the physical Earth that we walk
around on and it's very unlikely that it would be doing that therefore it's not an extraneous
conductive part and so it won't need connecting to earth now it's normally at this point in the
video that people start to think oh yes but what about for example when I made the video pointing
out that table tray generally doesn't need bonding there were various comments outlining situations
in which it could become live and therefore should be bonded I'll just give you one example now this
is really not to have a go at anyone's opinions or thought processes or anything like that but
someone outlined a situation where a forklift truck smacked into and dislodged some cables which
dangled down and came to rest on a metal tray so surely the tray being connected to Earth would
have been a good thing in that circumstance now that is a thought-provoking question and it did
give me pause I know they still look like hands but it's kind of a trap to think this way because
you could end up thinking about this endlessly so what if the cables got knocked by the forklift and
came to rest on a metal door handle someone on the other side could have come along and
touched the door handle and got a shock so should we have connected the door handle to Earth it's a
bit of an extreme illustration but it makes the point that actually what would have been better
would be to think about the installation and the risks to the k enabling so at the design stage it
should have been identified that a forklift truck was to operate in that area and so additional
mechanical protection was required for the cables or perhaps an alternative route should have been
found for them so coming back to our ceiling grids we've covered the fact that we shouldn't be using
them to support cables but we may be thinking well what happens if a fault occurs in a fitting that's
sitting in the ceiling grid won't that then cause the grid to become Live Well volume one of snags
and solutions by the Nic EIC comments on this making the point that any electrical equipment
installed in a suspended ceiling would normally either be class 1 or class 2. if it's Class 2 then
even if the outer shell is made of metal and rests on the ceiling grid this class of equipment should
be made in such a way that a fault occurring inside it can't result in Folker and flowing
into any conductive Parts with which the equipment may be in contact so in other words A Fault In the
equipment won't lead to the metal grid it its touching becoming live what about class one
equipment though A Fault in that could lead to the metal casing becoming live which if it's resting
in the ceiling grid could then also become live well maybe but if the casing of the equipment
is earthed as it should be then the parts of the grid will experience earthing via what the snags
and solutions guide calls fortuitous contact it concludes by stating that in normal circumstances
there is no need to arrange for the conductive parts of the ceiling to be connected to either a
main bonding conductor or to any supplementary bonding conductor so in short the answer is
generally speaking no the ceiling grid won't need earthing or bonding if you'd like to know
more about earthing and bonding check out these videos right here thank you very much for watching