T152
Energy measurements at home
T152 |
Energy measurements at home |
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To study T152 you will need to install a monitor which measures the electricity consumption of your home.
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This is one of the energy monitors supplied free with T152. It measures the electricity consumption of the entire home. Also supplied is another monitor for measuring any individual device plugged into a socket; it requires no installation and so is not described here. |
The monitor has three components:
Before you register for the course you MUST check to ensure that you (or a helper) can:
This Guide is to help you to carry out these checks and then to install the sensor.
Installing a monitor to measure domestic energy usage is a safe and straightforward process. Many hundreds of thousands of users have done it. The only part of it that worries some people, especially those who would normally avoid electrical cables like the plague, is the positioning of the monitor's sensor. The sensor clips loosely around a cable that comes out of the home's electricity meter. If you should try the wrong cable you will not harm yourself, your monitor or your electricity supply. You just won't get a usable signal until you find the correct cable.
That's it!
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Contents of the box. Clockwise from top left: AA batteries (4), transmitter, portable display, key (for meter cabinets), sensor. |
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A printed set of instructions comes in the packaging with your monitor. The instructions are also available online here (when the page opens click "Support" on left-hand-side and then "Fitting Instructions"). |
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Your meter is most likely to be indoors, attached to a wall. It
may be in a cupboard, or under the stairs, or in a cellar or porch. Some meters
are located outside, as in the image, either in a building such as a garage, or
in a cabinet fixed to the exterior wall of the house. |
Electricity meters come in various designs. The one here shows the two key features you are interested in.
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First, it has several cables in its base. As explained later, you will clip a sensor around one of the cables, so make sure you can reach them to do this. Second, it displays the current meter reading. Make sure you can note your reading without undue difficulty, as you will do so quite often while studying T152. |
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Some old meters, like this one, use dials instead of digits to display the reading. They are easy to interpret, but you might need to learn how. |
If you cannot locate the meter you need to seek advice. Ask your electricity supplier if necessary.
If the meter is in a cabinet you may need to open this with a key.
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The key is likely to be of a standard type that has a triangular hole in it. A standard key (made of green plastic) is provided with the Eco-eye monitor |
If the meter is physically risky to access -- for example if it's in a high cupboard out of direct view or at the head of some stairs, you must evaluate whether it is safe for you to install the sensor and transmitter and to take meter readings. In particular, make a judgement about whether you can eliminate the risk of slips, trips and falls. We suggest that you take the view that it is not safe unless you can satisfy yourself and others that it is. If it is not safe you must not proceed until you can acquire equipment or a helper to eliminate the risk.
If you live in a shared block of homes, its meters may be gathered together, as in the photograph below. This may look forbidding, but actually most of the boxes are fuse boxes (the ones with red rocker switches) and only one of the meters would be yours. There are usually labels to identify them. If you have a situation like this and you can't identify your meter, again you must ask your electricity supplier.
As you can see from the photograph, there are at least three types of meter (centre, bottom centre and bottom right) and possibly others. However, all that really matters for positioning the sensor is that you can identify the live cable from your meter to the correct fuse box.
You are looking for the live cable at the home's side of the meter.
Most electricity meters have four cables at their base. Those towards the left are "street-side"; those towards the right are "home-side". The live cable is the rightmost one, though it is better to think of it as "fourth from the left" (for a reason you'll understand in a moment). Sometimes it will be clearly labelled, as here:
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The L in the picture stands for Live, the N for Neutral. Sometimes the live cable is coloured brown, or red on older cables, but it may be unmarked and identical to the others (as mine is). |
Apparently some meters have two, six or even eight cables in the base. If there are two, the right hand one is the live cable. If there are more, the live cable is the fourth from the left, just like the usual four cable type.
But there are five cables in the picture!
We have deliberately chosen a difficult example here. In this closer view of the previous image, the two fuse boxes to the left of the meter distribute on-peak and off-peak electricity respectively. You can see this written on the top right of each box. Instead of one home-side live cable there are two, one to each fuse box. They both come from the "fourth from the left" meter terminal.
To study T152 you need to measure on-peak electricity*. In that case you would choose the cable from the meter to the on-peak fuse box. Tracing this carefully in the picture, we see it is the rear of the two cables from the fourth meter terminal. Electricity flows along that cable during on-peak hours and along the other during off-peak hours.
Some homes have a different arrangement for off-peak electricity, with two meters instead of two fuse boxes, which at least makes it easier to identify the correct cable, as long as you know the correct meter! Yet again, if you cannot find this by studying the labelling or by matching the meter readings to those on a recent electricity bill, ask your electricity supplier. You have every right to know which meter is counting your electricity usage.
*Although T152 does not require you to measure off-peak electricity, you may want to do so. If you want to measure it without moving the monitor's sensor from cable to cable, you will need two sensors instead of one. An extra sensor can be bought at a small cost from the energy monitor supplier (not the electricity supplier). Both sensor wires plug into adjacent sockets in the same transmitter unit.
Most homes are a lot easier to deal with than the set-up just described. Here is a meter with a sensor in position:
Follow the maker's instructions. There's no cable cutting, unscrewing or anything dangerous involved. The cable is well insulated, as you can see from each picture. You just clamp the sensor around the cable and clip it shut. It will probably be a fairly loose fit, which does not matter. The maker should be able to supply a larger sensor if for some reason you have a very fat cable (above 13 mm in diameter).
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The sensor does not penetrate the cable, because it works by sensing the surrounding magnetic field rather than the electrical current itself. |
Anywhere along the length of cable from the meter to the fuse box, wherever is easiest for you.
If the meter is situated outside your home, you might prefer to attach the monitor inside, near the fuse box. You should get a much stronger signal from a transmitter inside your home. Also someone else could interfere with a sensor and transmitter positioned outside.
The problem here is that if the meter is outside and you are inside, you may not know which cable to use. If so you have to resort to trial and error with each cable that enters the fuse box.
Again - don't worry. If you try the wrong cable you will not harm yourself, your monitor or your electricity supply. You just won't get a usable signal until you find the correct cable. The Eco-eye monitor provides a tiny lamp to put on the end of the sensor wire, which lights up when it gets a usable signal. And that's not all ...
You may hear a buzzing noise once the sensor is around the live cable. This is because the wire connecting the sensor to the transmitter is not yet plugged into the transmitter. The noise is just a consequence of the way the sensor works. There is no electrical connection between the live electricity cable and the sensor. Plug it into the transmitter and let it hum quietly to itself.
You'll notice in our pictures that there are no bare metal wires anywhere, only insulated cables. If you see bare or damaged wire, do not let anything touch it. If your live cable is unaffected you can still fit the sensor around it if there is no risk of disturbing the bare wire. But whether or not this is the case, if the bare wire is traceable to a meter or a fuse box, call the electricity supplier to come and check it, making sure to say that a bare wire is connected to your electricity supply and you fear it may be unsafe. A reputable supplier will come and investigate. If they don't, consult a qualified electrician.
Rather than rely on one supplier's instructions, we've compiled the following additional advice from all monitor suppliers who make their instructions freely available.
Finally, if you are in any doubt about positioning the sensor, consult a qualified electrician.
