Written by Dale Richardson - Updated: June 23, 2023
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Today we're discussing how to get your shed all set for some electronics. Whether this means you just want a light and freezer in there, or you're planning on turning it into a shop, we're here for you. At Fraffles, we do our best to know a bit of just about everything home-related - and your shed counts. So if you're considering running a line to your shed, knowing what size armoured cable for a shed is vital to doing it properly. And you do want to do it properly - otherwise, you risk having to do it again. That's no fun, now, is it!
What size armoured cable for a shed? This answer varies on the distance between your shed and home, though 6 and 10 mm are the most common sizes.
Let's talk a bit more about this, as it's actually a rather complicated question.
The first, most important thing you need to know when laying cable to your shed from your home is how far it is. This is because electricity is physically running along the length of your cable. The farther out your shed is, the better chance you have of the electricity dissipating before it reaches the shed.
For this reason, I highly recommend hiring a professional to do this work. There are a few other reasons:
Now that we've got that out of the way, how does distance play a role?
The big term you need to know here is volt drop . This term refers to how much power you'll receive from a cable over various distances. For example - you're running a 2.5 mm SWA cable with a 16 amp supply to your shed. If the shed is 40 or fewer metres from the supply, you're fine! On the other hand, if it's, say, 42.5 metres out, you'll not get the full 16 amps supplied. This is because volt drop occurs in 2.5 mm SWA cable at 42 metres.
Alternatively, let's assume you're running a 1.5 mm SWA cable with the same supply current. Now you can only go ~24 metres at most!
A solid rule of thumb is to assume that your shed is a "fixed appliance." This means that it's, for all intent, it's no better than a really big toaster. You're going to assume that there's always X amount of power being drawn at all times, and account for that. The issue here is that there's a good bit of math to know that, if we're being honest, I really don't understand. I'm a writer, not an electrician - that means I can tell you the numbers, but I can't explain them (unfortunately)
See, this is another thing that needs to be taken into account. If you're (for example) running power from your home to your shed, and then to a shop or other small building, the equation changes.
Let's say you are pulling 6 kW per building over a distance of 65 metres. Crossing 60 metres will require roughly 26 amps in total - but you should aim for 30 amps of possible power. It's better to be overprepared than surprised when you suddenly can't run something new in your shop.
Now I could talk about this all day and get nowhere. There are a massive number of things to take into account when laying electrical cables. Distance from the power supply and endpoint, number of devices and their electrical draw, futureproofing, and much more. The best thing I can do is show you a chart from an actual "electrical group" on SWA cables.
Take a look at this chart , and then it's time to make a decision - do you try to figure it out on your own, or do you swallow your pride and pay an electrician?
I say that because, at the end of the day, (again) I'm a writer, not an electrician. I can learn information, but I don't have experience actually laying cables and making these calculations. Do you know who does have that experience? Your local professional - they've done this before, and they'll do it again.
Alternatively, if you know the difference between clipped cables, direct or "in ducts," and free air cabling, you're welcome to try! But again, I have to emphasize how much knowledge goes into this.
If you're thinking "man, this guy really doesn't have a concrete answer," let me tell you why. I research and write for a living - that means that I'm pretty darn good at learning information on the go when I don't know the necessary things.
I spent nearly four times as long as I normally would, trying to research this. Do you know what the answer I got every time was? Hire an electrician to do it . This was coming from professionals who spent hundreds, if not thousands of words to explain this question, only to end with that advice. They would go into all of the nitty-gritty details, only to have the person they were advising understand ~15% of the total information. I'm no better than the homeowners in question, and I'm willing to bet that you have better things to do with your time than learn the intricacies of laying cable. So please - bite the bullet and hire an electrician to do this for you. They'll ensure your new shed is futureproofed, that you don't break any local regulations, and that you don't have to do it again .
Laying an armoured cable to a shed is a complicated task. It requires advanced knowledge of how electricity works and how to properly install cabling to ensure nothing goes awry in the future. If you take the risk of doing this yourself, you risk damageing your property, wasting money, and a failed project that you spent a long time completing.
As such, I highly recommend that you don't try to learn what size armoured cable you need for a shed, and instead ask a professional. They will properly install the cabling the first time, do it quickly, and you won't have to learn an excess of knowledge that you really just don't need. If you really want to do this yourself, I recommend that you consult with an electrician at the very least. They can advise you on the right course of action and help ensure nothing goes wildly wrong.
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