Electrical Wiring in Attic, Cables and Insulation

Electrical wiring in the attic can be one of the major potential hazards in your home if not carried out correctly. Unfortunately, as the wiring in the attic is rarely seen, access is often difficult and working conditions are tough, this is one of the areas where corners may be cut or things may not be installed quite correctly.

1) Are Electrical Cables in Attic Safe?  

The wiring in the photograph above was installed by a professional company and it shows. The electrical cables have been secured and run in straight lines away from any potential hazards that could adversely affect the cables. 

In this article we will talk about the things that affect electrical wiring in the attic space, how cabling should be installed and the things that need to be considered when doing so. We will look at existing attic wiring and junctions and examine what has been done wrong and what could be done better. 

So, what are the things we need to look for when checking the wiring in the attic?

• Ensure that electrical cables are installed away from insulation
• Ensure that cables are correctly secured
• Ensure that junctions are done correctly
• Check that wiring is not frayed or damaged
• Check for signs of moisture or water ingress

2) Ensure that cables are installed away from Insulation

Whilst thermal insulation in the attic space will keep our homes warm and prevent heating bills from becoming excessive, it is the arch enemy of electrical cables. You see, electrical become warm during normal operation and particularly when large amounts of electrical current flow in them. 

Under normal circumstances, cables are able to shed this heat and the installation should have been designed for them to do this effectively. When attic insulation is later added and covers or partially covers the electrical cabling, they can no longer dissipate this heat and will very quickly become too hot. 

This electrical attic hazard will increase the risk of house fires starting especially when there are combustible materials stored around the area as is typical of an attic. Unfortunately, the electrical system is not likely to trip the circuit breaker or blow the fuse under these circumstances. This is because the system will not be aware of the problem and has not been designed to operate under these circumstances.

If you have doubts about the safety of your attic wiring then try to check that your cables are installed on top of the insulation or contact your local professional electrician to check that things are ok. 

3) Ensure that cables are correctly secured

Any junction boxes, electrical cables and electrical connections should be secured adequately and, where possible, away from areas that are likely to receive foot traffic. For most wiring, this is possible but may not always be possible as there will inevitably be light fixtures that are installed throughout the ceilings below. 

Electrical wiring should be installed to minimize the likelihood of damage, impact, or water ingress. Where the attic space is boarded or is expected to be boarded, ensure that your contractor will take the necessary steps to avoid any likely damage to cabling. 

Such steps could include, re-routing cables where necessary and possible, raising the boarding on legs to avoid crushing insulation and electrical cables or only boarding areas that are free and clear to do so. Cables should be neatly clipped where possible and run away from any sources of interference. 

Cables that supply TV, Aerial, Data, and internet should generally be run a little way from general power cables to prevent interference and induced voltages from appearing on non-power cabling. 

4) Ensure that electrical junctions are done correctly

Are these Electrical Cables in Attic Safe? Well, we can see from the photograph below that there are a couple of junctions here. The first is the foreground is a couple of cables twisted together and taped up. This is unacceptable as a method of jointing a cable. The cable is also floating around in mid air and not properly secured. 

The cable feeds an electric shower so a lot of power is likely to be flowing through this cable resulting in heat. Poor electrical connections are a common cause for electrical fires and this cable is no exception as further along, exactly this had happened.

This electrical cable, had been subject to several repairs over the years and it was time for it to be retired and the cable to be reinstalled from the electrical panel. 

A builder had installed an electric shower that was far too power hungry for the circuit and this was exacerbating problems. One of the common electrical hazards that we see is old wiring such as old knob and tube wiring, lead sheathed cables, rubber sheathed cables or cabling without ground wire. 

Modern electrical cabling is generally copper wires coated in a PVC sheath. This cabling is established as being suitable for longevity and suitable for supplying the various applications around our homes. 

5) Check that wiring is not frayed or damaged

Where cabling is installed in the attic, wiring should ideally run clipped along the sides of floor joists or ceiling joists. Where cabling is installed directly on top of joists, it is likely to receive an unwanted impact at some point. 

Cables that are installed on top of the joists can also be subject to unwanted load from any materials that are stored in the attic space.

This can lead to cables that become damaged internally and will often result in breakers tripping or fuses blowing without an apparent cause. There is also a risk that materials stored on top of cables will present a fire hazard providing fuel for any attic fires that start, because of the crushed cables beneath. 

Where wiring has become frayed, there is a heightened risk of short circuits. Any wire splices or electrical boxes that are used to make connections for a light fixture (for example), should be installed such that single cable insulation is not on show outside of an enclosure and wire strands are correctly terminated so as not to present a danger.

6) Check for signs of moisture or water ingress

The photograph below shows that there was indeed some moisture or water ingress present in this electrical junction. The terminal screws have rusted significantly and combined with electrical overload have resulted in this cable becoming cooked! 

When rust appears on metal surfaces those surfaces become less conductive to electricity resulting in increased heat and fire risk for cables. 

The roof space in your home is quite commonly a source for moisture to develop. As heat rises from your warm home and meets the cold air in the attic, moisture can form and drip down onto insulation, cables, and other attic components. This situation is more common in older or historic homes.

The good news is that in a new home that is constructed to national electrical codes and building codes, this is less likely to occur. If there are signs of moisture in your attic then call in a professional to examine why this is occurring. Moisture will rot the building materials and electrical systems and cause expensive damage if left unchecked. 

If you are thinking are Electrical Cables in Attic Safe? then as we have discovered, there are many things to consider. 

7) Common Questions

7.1) Can you lay insulation over cables in the loft or attic?

In some cases, this may be a possibility. There is a greater likelihood that lighting cables are ok to be covered with insulation rather than other electrical circuit cables such as power socket, electric shower, and cooker cables. 

The issue is, if the cables are not already covered in insulation, then there is a good chance that the electrical system was not designed to cope with this type of external influence. To cover existing cables with insulation is risking a fire. Check with your electrician who may need to investigate the cable routes, electrical panel, and capacity of the cables before deciding if it is safe to cover them with insulation.

7.2) Can I drill loft or attic timbers to run cables?

Attic timbers are not designed to cope with drilling. There is a good chance that drilling loft or attic timbers will weaken them substantially leaving them unable to cope with the forces of snow, wind shear, the weight of shingles or roof tiles. 

You should consult a professional to discuss your reasons for drilling the timbers and to check if any roof restructuring is necessary before doing this. 

Cables in the loft are normally clipped on top of timbers where there is no risk of damage and run in a manner that does not damage the roof timbers in any way. 

7.3) What to do with electrical cables when insulating the attic?

First, before touching any wires or attempting to manipulate, move or work on wiring, make sure that there are no live wires and the electrical supply has been proved dead. 

There is often not enough wire to be able to re-route or move them and you will certainly need an electrician if you are planning to extend existing wires or run new electrical wires. A licensed electrician will ensure that the lengthening of electrical circuits and connecting of wires is done correctly and in accordance with the local and national wiring regulations. 

8) Summary

Where electrical wiring is installed in an attic or loft space, local and national building and wiring codes should be consulted and followed. This will involve the assistance of an electrician for this type of electrical work as they will be familiar with the wiring regulations. 

Insulation and cables do not generally go together so ensure that IF there is insulation interacting with your attic cables that it is safe and is not likely to cause a fire. 

Do not lay insulation over existing cables without checking that it is safe to do so.