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Electrical – Glossary of Terms

Electrical – Glossary of Terms

by | Apr 17, 2020 | Electrical, Useful Advice & Tips

We thought it might be helpful to have a list of regularly used electrical terms to help explain some of the sometimes confusing terminology used

Fused Spur

This can be switched or unswitched. It is a way of connecting an appliance without using a plug. It is commonly used with Boilers. The fuse holder can take different size fuses – 3, 5, 10 & 13amp

MCB (Mini Circuit Breaker)

These are commonly known as “Fuses” on Consumer Units. They are used to control individual circuits. In more modern Consumer Units, they are controlled by Levers. if the lever is pointing UP, the MCB is on, if it is pointing DOWN, the MCB is off.

RCBO (Residual Current Breaker with Over-current)

RCBOs are very much more common these days. At its most basic level, an RCBO is an RCD combined with an MCB. Effectively each circuit has its own RCD.
They make a Consumer Unit more expensive, but they are much more convenient for the consumer. If a fault developes on a circuit, only that circuit will be affected, leaving everything else working.

If the lever is pointing UP, the RCBO is on, if it is pointing DOWN, the RCBO is off.

RCCB (Residual Current Circuit Breaker) 

RCCBs are RCDs. Like RCDs, they are used to protect a collection of MCBs. Like RCDs, they can also be used as a Main Switch.

If the lever is pointing UP, the RCCB is on, if it is pointing DOWN, the RCCB is off.

RCD

An RCD, or Residual Current Device, is a device to protect against faults. It measures the current in the circuits that it controls. If there is an imbalance, it assumes that some of the current has leaked out and is causing a danger. The current is immediately (or, at least within 300 milliseconds) switched off and there is no longer any power.  

If the lever is pointing UP, the RCD is on, if it is pointing DOWN, the RCD is off.

RCDs are sometimes used as the Main Switch on a Consumer Unit

Surge Protection Device (SPD)

Surge Protection Devices are becoming increasingly common. The latest (18th) Edition of Electrical Regulations required that these devices be installed where an interruption to the power supply could cause a danger. 
Manufacturers are now including these as standard in many of their Consumer Units. They are designed to protect sensitive electrical equiment against fluctuations in the supply voltage. We now have many more sensitive electronic devices in our homes which could be damaged by fluctuations in supply. 

Bathroom in Horfield

Bathroom in Horfield

by | Apr 16, 2020 | Bathrooms, Recent Projects

This bathroom was a long-awaited upgrade of an existing awkward layout. The customer knew exactly what they wanted. A low window in the middle of one wall made the space particularly difficult, but we managed to maximise the usable space.

We completely stripped the bathroom.

As frequently happens, removing the tiles loosened the old plaster, which then also had to be removed.

The pipework for the new shower was installed in the wall. Several pipes under the bathroom floor were renewed and re-routed. Old lead pipe was also replaced, while we had the opportunity.

The new bathroom was then installed. 

The finished floor
Suspended Basin Cabinet
Help, I have no electricity

Help, I have no electricity

by | Apr 14, 2020 | Electrical, Useful Advice & Tips

So, this is quite a common scenario and there can be a number of reasons for it.

The first thing most of us would do, would be to look out of the window and check if the street lights are on, or our neighbours’ lights are on. In these days of easy communication, there’s a quick text/whatApp to the rest of the street/neighbourhood to find out if they are in the same boat. If they are, then its very likely that there is a local issue with your Electricity Supplier.
In the Bristol area, we are supplied by Western Power  Distribution. They have a Power Cut Map, so you can check whether they are aware of it and what they are doing about it. You can also contact them to report it, if they are not aware.

The problem only seems to be in my house

A much more common scenario is for the issue to be in your house. If that is the case, then it may not be anything serious, and is quite likely to be some thing that you are able to identify yourself.
If you have absolutely no power at all, anywhere in your house, it may be that your whole supplied is covered by a single RCD.

You may have a separate switch on its own, which may look something like this, or be labelled RCD:

Alternatively, you may have a Consumer Unit, which is controlled by a single RCD main switch. If that is the case then, it may look a bit like this.  Instead of a Main Switch, it has a module marked as RCD. This means that if one of your circuits develops a fault, your whole supply will be switched off until you have resolved the fault.

Don’t panic. This is quite likely to be something that you can resolve yourself, without needing to bring in an electrician. To find out whether this is the case, follow the procedure below. 

What is an RCD?

A Residual Current Device is a safety device which is now, fortunately, pretty common in most domestic electrical supplies.

If you’re not sure whether you have one, it should look something like one of the images below. There will usually be a small reset button on it, sometimes red or yellow. 

It will either have RCD, RCCB or RCBO written on it. 

How does an RCD work?

An RCD measures the current in the circuits that it controls. It measures the current leaving and returning. If there is an imbalance, it assumes that some of the current has leaked out and is causing a danger. The current is immediately (or, at least within 300 milliseconds) switched off and there is no longer any power. 

How do I reset an RCD?

RCDs are designed to be reset. Sometimes they trip for no apparent reason. They can be tripped by a lightbulb blowing. It isn’t always an indication of a problem.

If the lever on an RCD is in the DOWN position, it is off. To reset it, the lever simply needs to be pushed back UP. For some RCDs, it is necessary to push the lever fully downwards before it will let you push it back UP and reset.

In many cases, this will be fine. The RCD will reset and all will be well. However, if there is a fault on your system somewhere, the RCD may not reset, or may reset temporarily, only to trip again a few seconds/minutes/hours later. If this happens, then you may well have a problem which needs to be addressed. The RCD is telling you that something is not right and you need to investigate.

To work out whether this is something which you can resolve yourself, or whether you need to call in an electrician, there is a simple procedure to follow.

My RCD won’t reset. What should I do?

  • If you were in the house when the RCD tripped, ask yourself what happened just before the RCD tripped. If you had just turned the Kettle on, or switched on the Iron, there’s a possibility that this may be the cause of the problem. Fully unplug the Kettle/Iron and reset the RCD. If the RCD resets and stays reset, then you have probably found your culprit.

 

  • If you just drilled through a wall and the RCD tripped, there may be a strong link between the two events. It is quite possible that you may have drilled through, or otherwise damaged a cable. If you didn’t check the positions of cables prior to drilling, you have just learnt a useful, but possibly quite expensive lesson. Its time to call in an electrician to repair the damaged cable as soon as possible. It is quite likely that the RCD will not reset until the damage has been repaired.

 

Next time you get the drill out, it would be worth checking out one of our other posts on the inappropriately named Safe Zones. Contrary to their name, these are areas where it is actually dangerous to drill, as they could legitimately hide cables.

If you look at the Safe Zones post and realise that you did, in fact, drill straight into one of these safe zones, please call an electrician as soon as possible. There may be some brown scorch marks, or even a bit of smoke coming out of the hole – all signs that things are not well.

How to identify the cause of a fault

If neither of these scenarios applies and the RCD seems to have tripped for no reason at all, there is a straightforward procedure to follow, which in most cases will identify where the problem lies.

The principle is that one thing on one circuit is probbaly causing the problem. First you need to identify the circuit, then you need to identify the “thing” on that circuit which is causing you a problem.

Stage 1

Your Consumer Unit should be properly labelled. The RCD will be labelled and the fuses (or MCBs) controlled by it, also labelled. Hopefully it will look something like this:

Make a note of the names of the circuits which are covered by the RCD.

Firstly switch off the RCD and all the fuses (MCBs) controlled by it. All the levers should be pointing DOWN

In this case, lets imagine that RCD 2 is the problem. The circuits covered by RCD 2 are:

  • Downstairs Sockets
  • Water Heater (Probably the Boiler)
  • Upstairs Lights

Turn off all those fuses (Lever pointing DOWN). Then unplug everything that is plugged into the Downstairs Sockets.

If the Boiler is also not working, and you don’t have an immersion heater in your house, it is quite likely that the “Water Heater” circuit applies to the Boiler. If it is plugged in, pull the plug out. If it has a fused spur, then pull the fuse out of the fuse holder on the fused spur.

At this point, still with all the fuses turned off, try to reset the RCD. If the RCD stays in the ON position, then you have successfully completed Stage 1.

Stage 2

Now, we need to identify which circuit is causing the problems.

Start with one circuit. In this case we’ll start with the Downstairs Sockets.

First turn on the fuse (MCB) for the downstairs sockets, and see if the RCD also stays on.

If it doesn’t stay on, check that you have definitely unplugged everything on that circuit.

  • Might there be something plugged in in a cupboard that you had forgotten about?
  • Is there an outside socket?
  • Are the lights under the kitchen cabinets run from a fused spur in the Kitchen?

It is very easy to miss something at this stage, so you may have to really rack your brains. Cooker Hoods are an easy one to miss.

If you are pretty sure that everything has been unplugged and you still can’t reset the RCD, it is time to call an electrician. This scenario (which is pretty unlikely) would suggest that there may be a problem with the wiring or something on the circuit.

If the RCD remains on, then go round and plug in each of the appliances that you previously unplugged. Switch each one on. If at any stage, the RCD trips, you have found your culprit.

If the RCD remains on while you plug everything back in, it appears that the problem isn’t on this particular circuit.

 

Stage 3

Move on to the next circuit and do the same thing.

In this case, it is the boiler circuit, so it will just be a case of putting the fuse back in and switching the boiler on.

If the RCD trips at this point, there could be an issue with the boiler. Take a look to see if there are any signs of water under the boiler. A leak from a boiler onto the controls is a common cause of this kind of problem. If you suspect that this is the case, you need to call a Gas or Boiler Engineer.

 

Stage 4

Finally turn on the third circuit. In this case, it is the Upstairs lighting Circuit. To save time,  you have left all the light bulbs in their fittings. If the RCD trips when you turn the fuse (MCB) for the lights back on, take all the lightbulbs out, just in case one of them is causing a problem, and switch the Fuse back on.

If the RCD stays on, put each light bulb back into its fitting in turn. For safety’s sake, make sure that you turn the fuse (MCB) off each time that you put a bulb in, and turn it on once the bulb is in position.  If the RCD trips when you put one of the bulbs back in, then that will be your culprit.

 

Hopefully you will have resolved the problem. However, if you have any worries, or need a bit more advice, please don’t hesitate to contact us.

 

Consumer Units – an introduction

Consumer Units – an introduction

by | Apr 12, 2020 | Electrical, Useful Advice & Tips

What is a Consumer Unit?

A Consumer Unit may be aclled many things; a Distribution Board ot a Fuse Box. Just for consistency (and ease), we will call it a Consumer Unit, or CU for short.

Whatever you decide to call it, it is the means by which electricity is distributed throughout your house.

At its most basic level, it should have a Main Switch, (to allow you to turn off the whole electrical supply to your house), and a number of different size fuses, or MCBs, which control the indiviudal circuits within your house.

Consumer Units come in many different shapes, sizes and levels of safety. We will highlight some of these  below.

Types of Consumer Units

CU with Re-wireable Ceramic Fuses

This CU has ceramic rewireable fuses, housed in a wooden box. If a fuse blows (stops working), it needs to be removed and the fuse wire running through it replaced. It is quite a fiddly operation, particularly in the dark, when you can’t find the fuse wire.

This type of CU will protect your circuits against overloading. The fuse wire should break if the demand is too high. It will not protect you against electrocution/serious injury or death, if a fault occurs and you come into contact with an electrical current.

These are very beautiful to look at, but belong in a museum. If you have one of these, we would recommend that you call an electrician in as soon as possible. It needs to be upgraded to something a lot safer.

 

CU with re-wireable Fuses

These are still pretty common. We see them in many houses. As with the first CU, these only provide you with protection against overloading a circuit.

Both of these CUs allow you to reset the fuses by either pushing a button or moving a lever, rather than re-wiring the fuses, which makes them slightly easier to operate.

If you have one of these, and you want any electrical work carried out in your house, some form of upgrading will have to be carried out before that happens. Current safety regulations will not allow electrical work to be carried out without RCD protection.

These CUs will not protect you against electrocution, if a fault occurs.

CU with Main Switch & RCBOs

This CU has a Main Switch and a mixture of individual fuses (MCBs) and RCBOs.

The circuits protected only by an MCB are protected against overloading. Under current regulations, the lighting circuits, which are only protected by an MCB will need their protection upgraded to an RCBO, if any work is carried out.

The circuits protected by RCBOs, are protected against overloading and electrocution.

CU with RCD as a Main Switch

This CU has an RCD which operates as a main switch.

The benefit of this CU, is that you have RCD protection. This will protect you against being electrocuted if a fault occurs.

The downside is that all your circuits are controlled by that single RCD. If a fault occurs on one of your circuits, then none of your circuits will operate until that fault is repaired. This can be a bit of a nuisance.

 

CU with RCD as a Main Switch

Until recently most old CUs were upgraded to this kind of Dual RCD CU.  Initially they were made of plastic, but in the past few years they have been made of metal, and greater emphasis has been placed on fire-proofing them.

The circuits in the house are divided into two parts, each controlled by an RCD. If a fault occurs on one RCD, then all the circuits covered by that RCD will be switched off, but the other RCD continues to operate, as do the other circuits.

This is a lot more convenient arrangement.

CU with Individual RCBOs

This newer style CU complies with the most recent regulations.

It has a fire-proof metal enclosure.

Each circuit is controlled by an individual RCBO, which gives RCD protection. If one circuit develops a fault, all the other circuits continue to operate.

In addition, the CU has a Surge Protection Device.

This type of CU is more expensive than the previous CUs, but it offers a higher level of protection and conveneince than all the previous CUs

 

Labelling

As you will see in many of the above pictures, much of the labelling on Consumer Units can be a bit patchy. It is really useful to know which fuse (MCB) covers which circuit. In the event of an emergency, this may be something you need to know in a hurry.

If your Consumer Unit is not well labelled, this something that you can improve yourself, with the use of some clean white labels and an hour of your time.

Go through each MCB in turn. Switch it off, and identify which sockets/switches/lights etc are no longer working. Make a careful note of what these are and keep the recorn with your Consumer Unit.

You can then update the label on the outside of your Consumer Unit.

Electrical – Safe Zones

Electrical – Safe Zones

by | Apr 12, 2020 | Electrical, Useful Advice & Tips

Where is safe to drill in a wall?

 

This is, understandably, a very important thing to know. There are 4 main areas where you can definitely expect cables to have been run:

At the top of walls

An area 150mm (6 inches) wide along the top of the wall where it meets the ceiling.

 

Where the two walls meet

An area 150mm (6 inches) wide where one wall meets the next wall

 

Horizontally either side of a switch/socket

In a straight line either side of a socket/switch/fused spur etc. The line is the height of the socket/switch. It runs all the way to the adjoining walls, or an obstacle, such as door or window.

 

Vertically above and below a socket/switch

In a straight line above and below a socket/switch/fused spur etc. The line is the width of the socket/switch. It runs all the way to the floor and ceiling.

 

Important

If the wall is less than 100mm (4 inches) thick, then the safe zones operate on both sides of the wall. Bear this in mind when you are drilling from a different room!

 

Very very important

Electricians in the past did not have these rules. Cables could be, and were run in all sorts of odd places.

We have found cables run diagonally across walls, doing sudden 90 degree bends and all sorts, so beware. 

If you suspect that someone in the past has carried out some electrical DIY in your house, it is quite possible that they did not know about Safe zones. They may have run cables wherever was most convenient for them, not always in the safest place.

If your current consumer unit does not have a functioning, healthy RCD,

In fact, if you have any doubts at all,

TURN OFF THE CONSUMER UNIT BEFORE YOU DRILL

Where is it safe to drill in a ceiling?

The rule that electricians should follow is to run the cables through the joists, as close to the centre of the joist as possible, at a depth of at least 50mm from the top and bottom of the joist. i.e 50mm from the ceiling/floor.

It is not always possible to follow this rule. There are often existing holes and notches in a joist. It is extremely likely that in times past, cables have been run all over the place.

It is also quite possible that cables can be lying on top of plasterboard ceilings.

Because it is not always possible to run cables this way, the current electrical regulations allow cables to be run outside the zones, provided they are protected by an RCD.

If the wiring in your house is old and you have a Consumer Unit which does not have an RCD, then you should be even more cautious. If you have any doubt,

TURN OFF THE CONSUMER UNIT BEFORE YOU DRILL

Where is it safe to drill in a floor?

As with ceilings, the rule that electricians should follow is to run the cables through the joists, as close to the centre of the joist as possible, at a depth of at least 50mm from the top and bottom of the joist. i.e 50mm from the floor.

It is not always possible to follow this rule. There are often existing holes and notches in joist, and it is extremely likely that in times past, cables have been run all over the place. It is also extremely likely that gas & water pipes have also been run under the floorboards through notches in the joists, (in which case, it is worth checking very very carefully first) 

Because it is not always possible to run cables this way, the current electrical regulations allow cables to be run outside the zones, provided they are protected by an RCD.

If the wiring in your house is old and you have a Consumer Unit which does not have an RCD, then you should be even more cautious.

If you have any doubt,

TURN OFF THE CONSUMER UNIT BEFORE YOU DRILL