- In this Q&A video,
we're going to answer the question,
"What do all these emergency lighting terms mean?"
Just before we explain the answer to this question,
please be aware that this video is one of a series
that we've made on the subject of emergency lighting
in association with ROBUS.
They can be viewed individually,
or you can click the link in the description below
to view them as part of a free online training package
to help you with your CPD,
and you'll receive a certificate
to prove you've completed the course.
When you're starting to grapple with emergency lighting,
it can feel a bit overwhelming
as all sorts of phrases and expressions get banded around
and they're very easily confused with each other,
so we're going to explain them here,
and this will help you understand
the rest of the videos in this series.
BS 5266-1 is the standard that acts as the base guidance
for the subject of emergency lighting.
It represents incredible value
at a mere 410 pounds for BSI non-members.
If that's a little outside your physical endeavours,
then the "Electrician's Guide to Emergency Lighting"
covers much of what's contained in the standard
with a particular slant towards electricians.
In BS 5266-1, we find Annex F,
which describes seven different modes of operation
that emergency lights can operate under.
These are reproduced in Table 4.4
of the "Electrician's Guide to Emergency Lighting,"
and you can see that each one
is given a number from zero to six.
Zero is non-maintained.
This means that the fitting is never illuminated
as long as the supply to it is healthy and connected.
When the supply fails due to either a power cut,
a fault that operates the circuit protective device,
or for some other reason that disconnects the supply,
the battery inside the light fitting
will connect to the light source
and keep it illuminated for a period of time.
If the power is then restored,
the battery will start to recharge
ready for the next power failure.
One is maintained.
This type of emergency light is on at all times,
so if the power supplied to the fitting
is healthy and all is well, the light will be on.
If the circuit feeding the fitting fails for some reason,
the light will remain on,
but now being powered by the internal battery.
These two base modes of operation are then repeated
with other types of emergency lighting.
Those of us who are a bit longer in the tooth
may remember another type of lighting
that we used to call sustained.
This is where an emergency light fitting
would contain two or more lamps.
At least one of these were connected to the backup supply
and would illuminate when the power to the fitting died.
The remaining lamp or lamps
were connected to a switched line conductor,
which could be turned on and off when light was needed.
This method of emergency lighting still exists,
but you won't find the term sustained
anywhere in BS 5266-1.
It is correctly referred to as combined.
Mode of operation two is combined and non-maintained.
Mode of operation three is combined and maintained.
For the next mode of operation,
we're going to skip ahead a little and discuss number six.
This is what's referred to as satellite.
Now this is where you have an emergency light fitting
that doesn't have a battery backup supply inside itself,
but rather derives its emergency supply
from another emergency fitting.
The fitting it gets its emergency supply from
is referred to in our fourth and fifth modes of operation
as compound self-contained emergency fittings.
Number four is compound non-maintained,
and number five is a maintained version of this fitting
giving us compound maintained.
Just one further thing to note about this table
is that it's used to create codes
that identify the characteristics of emergency lighting.
So, rather than reading each row from left to right,
which could fool you into thinking
that all self-contained, non-maintained emergency lights
include test devices
and only need to last for 10 minutes,
rather, each characteristic is selected by column
and then combined to give a code
that tells you information about the emergency light.
Now, you may have noticed
that I added the word self-contained
to the description of the compound fitting.
So why did I add it in?
Well, it's to differentiate it from a whole other type
of emergency lighting system, namely centrally supplied.
So what does that term mean?
Well, we've discussed so far,
there's six different modes of operation.
We're now going to consider
the two different types of emergency lighting system.
A self-contained emergency fitting
is one that contains the battery backup supply inside itself
with the exception of the satellite fitting.
A centrally supplied emergency luminaire
is more likely to be a part
of a whole system within a building
that provides a backup power supply from a single point,
either a large battery bank or possibly a generator,
both of which are designed
to spring into life in the event of a power cut.
There's advantages and disadvantages
to both types of systems,
but it's fair to say the vast majority
of installations use self-contained fittings.
These two types of system are given
their own designation code,
which is X for self-contained,
and Z for centrally supplied.
We're now going to consider some
other terms connected to emergency lighting,
which relate more to the way the lighting is used.
Let's paint a picture here.
Imagine that it's night
and a fire's broken out in a building.
The insulation on the cables has melted in the fire
causing protective devices to operate,
and the lighting circuits have therefore lost power,
so the building is on fire,
and it's completely dark inside.
What do you do?
Well, in a well-designed
and even better maintained building
the emergency lighting will have kicked in,
and depending on where you are
and what you're doing in the building,
it will be fulfilling one of several options.
These options break down into three broad areas:
emergency escape lighting, emergency safety lighting,
and standby lighting.
First up is emergency escape lighting.
This is further broken down into three further categories.
The first of these is escape route lighting.
In a large building, there are designated routes
to get out of the building in an emergency.
These have to meet certain requirements
to limit the occurrence or spread of fire through them
so that they stay clear through evacuation purposes.
One of these requirements
is to have emergency lighting in place
that will illuminate the route to a sufficient level
to allow people to see their way
along the evacuation route to a place of safety.
This is usually to the outside of the building.
Interestingly, this category of lighting
also includes a further subcategory of safety signs.
So escape route lighting is also used
to illuminate safety signs,
and firefighting and safety equipment
that may be needed in an emergency.
This subcategory is so important
that we're going to devote
a whole video to it later on in this series.
Moving on to our category of emergency escape lighting,
we've got open area anti-panic lighting.
In something like a large sports hall
in an educational building or a leisure centre,
it may not be clear how to get out
in the event of an emergency,
and therefore there needs
to be enough emergency lighting to see by
and also indicate the direction to leave in.
It's typically required in areas
of 60 metres squared or more,
but may be needed in smaller areas
if there's an additional hazard,
such as used by a large number of people
who might obstruct signs.
Then there's the third category
of emergency escape lighting,
which is high risk task area lighting.
This is required in areas
to protect people who are engaged
in potentially dangerous processes or situations
and need sufficient light to shut things down safely.
A good example is an industrial kitchen
where people are working
with sharp knives, boiling hot fluids, and naked flames.
Now we move back up the hierarchy of emergency lighting
and move across to emergency safety lighting.
Notice that now we've lost the word escape
from this type of lighting.
There are of course reasons why standard lighting
may be disconnected from the supply
other than a fire breaking out.
It may be due to a fault
on a circuit or an external power cut.
In some circumstances, evacuation of the occupants
may actually present a higher risk to them
than keeping them in the building.
A good example might be a care home
where moving elderly or infirm people outside
could cause injury or harm through exposure.
If that's the case, then it can be better
to leave people where they are
but still ensure that there is sufficient emergency lighting
to allow a measure of comfort and reasonably safe activity.
This is what we mean by emergency safety lighting,
and you may hear it referred to as stay put lighting.
Of course, there are limits
to how long emergency lighting can be provided for,
and situations change,
so there may come a point where it is necessary
to evacuate even elderly or infirm people,
and so emergency escape may become necessary
if say, there's only one hour
of emergency lighting left in the system.
These decisions will be made
by the responsible person.
More on them in a later video.
Then moving across our chart, we come to standby lighting.
Notice this is separate
from emergency escape and emergency safety lighting.
It's emergency lighting that is designed
to allow normal activity to continue
in the event of the general lighting failing.
It's intended to minimise disruption
to normal activities when lighting fails.
Interestingly though, it's a requirement
that if the light levels provided
by the emergency standby lighting
is lower than the level of light provided
by the normal lighting system,
it should only be used to shut down or terminate processes.
It's different to high risk task area lighting
as it can be required for less dangerous activities
and can be designed to keep activity going
rather than just facilitate shut down and escape.
The requirements for standby lighting
are also far less stringent and specific
than high risk task area lighting.
So there we go.
That's some important definitions
of terms used in connection with emergency lighting,
but you may be wondering about
some of the requirements and practicalities
of actually installing emergency lighting correctly.
Well, to find out more,
check out this video right here,
or click the link in the description below
to watch it as part of our free training package
to help you with your CPD,
and you'll receive a certificate as well.
For further information on emergency lighting from ROBUS,
check out their latest catalogue,
or get in touch with them via email on info@robus.com.
All that remains in this video
is to say thank you very much for watching.