How to Drill Holes for Electrical Wires –

We explain how to drill holes for electrical wires. At some stage, as a homeowner, you may have to try and drill a hole, or holes for various types of wires and cables. There are of course many types of cables and they include electrical cables, TV aerial cables, phone cables, home security and even different types of computer cables.

In addition to the different types of cables, you may have to also drill through different types of wood, metal and even some pretty tough masonry. In this article we offer as much guidance as we can to help you get on with getting the job done.

This is the easy question to answer. Almost any drill will get you through wood and metal as long as you have the right drill bits, and as long as the drill is powerful enough. A good household drill will do the job nicely, and that can either be a corded drill or a cordless drill.

If however any of your cables need to go through masonry such as brick, block, or concrete then you will need a drill that has a hammer action. It is this hammering action that allows the drill to move backwards and forwards as well as rotating.

If in doubt make sure that you buy a drill with a hammer action as that can be used to drill through any type of material. Something like the Bosch PSB 1800 is a big seller, affordable and a very good choice.

The important thing to figure out is the size of the hole that you need to drill. You also need to consider how deep the hole is that you want to drill. In most cases you will need to drill all the way through. That will determine the length of drill bit that you need.

Standard drill bits are around 3-4″ in length and in most cases will do the job for things like joists. For something like a door frame or a cavity wall, you will need to buy a longer length bit. The thickness of the hole is also an important consideration. Electrical cables for example are much thicker than phone cables, security camera cables or TV aerial cables.

All you have to do is quickly measure the diameter of the cable, and then make sure the drill bit that you pick, is slightly bigger to allow you to drill the hole. The cable should be able to easily pass through the hole without being forced through.

The depth of the hole is also important. Most standard drill bits are not that long and have been designed to drill a hole 3-4″ deep. As I have mentioned, going something like drilling through a cavity wall, will require a much longer drill bit than a standard sized one.

You can buy a standard set of drill bits which come in different diameter sizes, and these are not that expensive. Likewise you can buy a set of longer drill bits in a set, or buy those as individual drill bits.

Cavity walls are made to help provide insulation for homes. Two rows of bricks are laid side by side so as there is air in the middle. When that air is warm, then that helps provide the insulation. Often this gap can be filled with cavity wall insulation that really does help keep the heat in.

However when it comes to drilling through that, then your drill bit needs to be long enough to go through two sets of brick and the gap in between. A standard brick is 215 mm long, 102.5 mm wide and 65 mm high.

With a cavity wall you will have two widths of brick and the gap. The average gap can be anything between 20-100 mm wide depending on the building regulations. So you could be looking at drilling through 102.5 + 102.5 + 100 so around 300 mm.

That is 12″ in the old measurement and that will require quite a long drill bit.

In the video below, you can see how to properly drill a hole through a cavity wall using a longer drill bit, and a hammer drill. In this video plastic pipe is used to protect the cable.

It would be unusual to have to drill through metal to place cables through. It is certainly unusual in the home, but there may be the odd time when you have to do this. You may come across it where there is conduit, or some type of metal frame.

Metal is actually pretty easy to get through as long as you have some form of metal drilling bit. The one thing you want to avoid with metal is leaving a sharp edge. That of course could damage the cable and more importantly damage you. For holes you should use something like a rubber grommet to protect the cables.

You can see how to use those in the video below.

Most homes in the UK have been wired by a qualified electrician. The new regulations clearly state that the work must meet the requirements of Part P of the Building Regulations.

There are however times when you may need to do a simple task like running a cable through some material, be that wood or masonry. We do want to say that if you are doing this yourself, then of course you need to stay safe, and also be 100% sure of what you are doing.

Many people will simply want to neatly run through a longer extension lead, through a door frame or something similar to that. To achieve that all you need is a normal drill, a wood bit that is big enough and then drill the hole. Pass the cable through and then connect it up.

If you are running the main types of electrical cable for something like an attic extension, a loft conversion or a garage conversion, then you should be familiar with the main basic types of electrical cable. We have shown those below along with the actual diameter sizes. You need to drill a hole big enough to cater for the cable you are running.

• 1mm Twin and Earth (4.35 x 7.95mm)
• 2.5 mm Twin and Earth (5.65 x 10.65mm)
• 4mm Twin and Earth (6.3 x 11.95mm)
• 6mm Twin and Earth (7.1 x 13.7mm)
• 10mm Twin and Earth (8.7 x 17.25mm)

Here is a useful video that shows you how to drill holes through joists for electrical cables. Typical sizes of holes for cables are 16 mm or 25 mm holes.

There are two types of telephone cable and those are external cables and internal cables. In almost every single case home owners only ever need to deal with the thinner internal cabling.

The external cabling is always fitted by the telephone engineer and they will drill that through from the outside and then fit a box on the wall. From there it is then possible to run internal telephone cables for extensions in the home.

The only time that you would ever need to consider an external cable is if there is some type of refurbishment taking place in your home, and you need to move the external cable. You should contact your phone supplier to arrange this and there will be a charge.

Some builders may do this for you, but they really should not do that.

Internal Telephone Cables

These are very thin and usually around 15 mm. You can also buy junction boxes and internal extension boxes. Some home owners will tack the wires around the skirting board and door frames but this does look untidy.

The majority will drill a hole through door frames and hide the wire under  carpets. That is neater and you do not need to drill a very big hole.

The only thing that you need to be careful with, when it comes to phone cables is that it is really easy to damage, so always treat it like that.