Powerline adaptors turn your electrical cables into a speedy network, and will revolutionise the way you download movies, TV programmes and browse the Internet in your home.

If you have a smart TV or watch catch-up TV via Sky, Now TV, Apple TV or the many other set-top boxes, use Skype for video calls, or play games on your console, then Powerline (also known as HomePlug) could be the answer to your faster download prayers. See: Best Powerline adapters

Powerline vs Wi-Fi

Wi-fi is pretty much in every home these days. Smartphones, tablets and laptops demand it. And now so do TVs, games consoles, Sky+ and Tivo boxes…

But, as we all know, Wi-Fi signals lose strength the further away you are from the wireless router and especially as you move to other levels of your house and through different rooms.

You might not notice this on your smartphone but you will when you try to download a movie to your TV.

There’s something much faster than Wi-Fi, and that’s a wired connection using an Ethernet cable, just like the one that connects your router to your PC or Mac. You lose less data to the limitations of Wi-Fi, which loses strength the further you are away from the wireless router, hates going through walls and gets interference from all sorts of other devices and structures.

How to set up Powerline

Snaking Ethernet cable round your house is, of course, not practical. What you need is Powerline – an incredibly simple, straightforward to set up technology that instead uses your home’s power cables instead of Ethernet.

Powerline technology turns your home's electrical wiring into a network. You need at least two Powerline adpators – and most starter kits come with everything you need: adaptors and Ethernet cable.

Playing with electrical sockets isn’t recommended child play but Powerline really is childplay for adults to set up – even if you think you know nothing about technology. All you need to be able to do is use a plug and connect a couple of cables. It really is plug and play.

Simply plug a Powerline adaptor into a power socket near your router, then connect that adaptor via Ethernet to the router. Now take another Powerline adaptor and plug that into a power socket in another room – say, next to your TV. You can then connect this second adaptor to your TV using another Ethernet cable. Bingo, your TV – or Sky+, Tivo, laptop or whatever – is now wired to your router, and so should enjoy much faster download speeds than via Wi-Fi.

It will also set up a basic computer network if you want to share files around the house.

Powerline wifi house plan

Powerline Wi-Fi hotspots

Some Powerline adapters have additional Wi-Fi functionality. Such adapters create a new Wi-Fi hotspot in rooms around the house. They use the same Internet supply you get from your wireless router but create a brand-new hotspot so you don’t lose signal strength through distance from the router. (You do lose some signal strength via Powerline but in our tests it improved around-the-house Wi-Fi signal strength by as much as four times.)

This should mean much faster laptops, smartphones and tablets to play with while you watch your iPlayer shows on your Powerline-connected TV.

Powerline speed myths

But, be warned, all Powerline adapters come with hugely inflated speed claims. Ignore these boasts because the actual speeds that we’ve tested are plenty fast enough for most home network needs.

Every Powerline/HomePlug maker claims their adaptors can carry data at speeds of 200Mbps at the entry level to 500Mbps or 600Mbps, and 1,200Mbps for the fastest. These claimed speeds are the theoretical maximum speeds of the chips used within the adapters.

As the whole point of Powerline is to speed up your home network we’ve tested a bunch of the 1,200Mbps, 600Mbps, 500Mbps and 200Mbps Powerline adaptors. See which Powerlines we recommend in Best Powerline adapters.

Let’s be more honest than the manufacturers – and they’re all at it – you won’t get 500Mbps from a 500Mbps Powerline adapter. You’ll be lucky to get 100Mbps for a multitude of reasons, including age of your power cables, distance between adaptors, “electrical noise”, mains fluctuations, interference from other devices such as phone chargers, and circuit breakers.

Logitech has created a good list of why Powerline is limited by house environmental factors.

This loss of strength is known to technical types as “signal attenuation”. So let’s forget the 500Mbps claims – except to recommend the “500Mbps” kits over the definitely slower “200Mbps” Powerline kits.

200Mbps Powerline will achieve speeds between 20 and 90Mbps, while 500Mbps kits reach speeds between 20 and 200Mbps. In our tests 500Mbps Powerline was an average twice as fast as 200Mbps Powerline kits, and the gigabit 1,000Mbps or 1,200Mbps about a third faster still.

Another important factor is the speed of the Ethernet connection. Many of the so-called 200Mbps and 500Mbps Powerline adaptors feature one or more 10/100 Ethernet ports. If this is the case the maximum speed you’ll get is 100Mbps because the Ethernet connection maxes at that rate. For faster possible speeds look for a Powerline adaptor that has ports using the Gigabit Ethernet standard, which has a theoretical maximum speed of 1,000Mbps.

It’s also worth remembering that your Powerline setup will only ever be as fast as your broadband speed when downloading files, movies or catch-up TV.

If you use the Internet just for casual web browsing, streaming music or a few non-HD telly shows then 200Mbps should be all you need. For streaming HD movies and TV shows, sharing files around the home, or if you use lots of web devices at the same time we recommend the faster 500Mbps Powerline products.

Testing Powerline adapters

We try to test all the latest Powerline adapters, and compare their speeds to see which is fastest.

Some reviews claim Powerline speeds much higher than those in the PC Advisor Powerline comparison tests, and you should be wary of trusting them.

We test using real-world situations, transferring a 1GB file multiple times between computers to test the average speed of a home network.

Speeds will vary between different buildings, and that’s to do with the age of the home’s wiring, and many other environmental issues.

But many Powerline reviews use the manufacturer’s own speed-testing app to gauge performance, and that’s not going to give you a proper idea of how fast one Powerline adapter is compared to an other.

Only PC Advisor tests give you real-world Powerline testing.

The Mbps speed shown in Powerline apps such as Devolo Cockpit, is the “physical data rate” (gross data rate). It is the amount of “zeros and ones” that is transmitted in a certain time.

If you transmit a 1GB file (also called user data) you also transport overhead (address data, error correction, modulation data,etc). So the amount of user data (also called net data rate) is, depending on the user software and protocol, about 50 percent of physical data rate.

Trust real-world tests if you want to see which Powerline adapters are the fastest.

Powerline home ethernet passthrough

Powerline Pass-through socket

Some Powerline adapters include a pass-through power socket so you don’t lose that power source for other devices. Basically the pass-through socket allows you to slot another device’s plug into the Powerline adaptor. It's also claimed that using the pass-through socket actually shields the signal strength from other limiting electrical noise. It does make the adapters a bit chunkier but saving the power socket is a real benefit.

What’s included in a Powerline starter kit

You need at least two adapters to create a Powerline network. Some kits come with three, and you can usually buy extra single adapters as you need them. If buying online be careful to ensure you are buying two rather than one adapter.

Unlike manufacturers who make you buy a USB cable when they sell you a printer most Powerline kits include at least one Ethernet cable.

We have rounded up the best Powerline adaptor kits, and rigorously tested them under the same conditions to find out how they compare, and recommend the best products to you.

Powerline recommendations

• Buy 500Mbps or 600Mbps Powerline if you can. You should score twice the speed than you get with 200Mbps Powerline. Powerlines claiming 1,200Mbps are now available, and these are faster but pricier.

• If you use Wi-Fi at home and your router is tucked away from where you usually access the Wi-Fi then splash out on a Powerline that will set up a new Wi-Fi hotspot where you need it most. The new Wi-Fi hotspot is far less restricted than one several room and floors away.

• Consider looks. It might seem vain but you probably don’t want a giant ugly thing sticking out of a power socket in your living room. BT’s Powerline adaptors, for instance, perform really well but are huge black beasts. If you can hide it away then fine. If it’s in plain sight you might prefer something less obtrusive.

• If you’re short of power sockets consider one with a pass-through that lets you connect another plug through the Powerline adaptor.

• How many Ethernet ports do you need in the second room? My home setup requires at least two, and preferably three. My Sony smart TV needs one for iPlayer, YouTube and Amazon Prime Video. My Sky+ box needs one for catchup TV. And sometimes I might want the fastest possible downloads on my laptop. My smart thermostat would also like to be on the ground floor, too, and that has an Ethernet gateway. Most Powerline adapters come with just the one Ethernet port, which is fine if you just need one or are happy to swap out the cables for the device you need at any one time. The TrendNet Wi-Fi Powerline adapter has two ports, as does the TP-Link AV500. The Devolo 500AV and 650 triple+ adapters have three.

• Go for an adapter with Gigabit Ethernet ports if you can. It won't make any difference unless your computer and router are Gigabit Ethernet too but if they are then you're better sticking with the fastest version. You can use Gigabit with slower systems, as they are backwards compatible. You just won't see any speed benefit. If you use 10/100 Ethernet with a Gigabit system then you'll be pegged back to the slower protocol.

* If your power sockets are located very close to the floor then adapters that have the Ethernet ports on the top are better than those at the bottom.

Powerline tips

• If you want the fastest download speeds disconnect your phone and tablet chargers, wherever they are in the house. These things really mess with the speed as they cause huge interference on the powerlines.

• Try not to use the microwave while downloading.