Cable run to obs?

[Jarndyce]

I want to run a mains and ethernet cable to my shed a the bottom of the garden, which will eventually become an obs.

I intend to run them both in flexible trunking and use an RCD at both ends.

Run is around 35-40m.

Any suggestions as to what kind of mains cable/trunking I should use?

[Psychobilly]

I used armoured cable a lot more expensive but the safest way to do it.. and fit and forget really its designed to be buried underground in trenches...... get a couple of Steel juction boxes and the proper termiantion glands use 3 core armoured cable don't use the armouring to carry the Protective earth.

1.5mm2 will be fine for up to 2.1 KW (9A) over 45m ... use this Calculator for sizing ... if you want more power capacity in the obs then use 2.5mm2

The steel armouring also helps with the shielding as your not supposed to run Mains and Data cables parallel to each other in close proximity...

I would just use an RCD at the house end make it would protect agaisnt any "faults" in the cable ...

I have installed a 1m long copper earth spike into the obs floor and have this bonded to the observatory pier and "water" it from time to time...

Peter....

[Jarndyce]

Thanks for the advice Peter.

I've tested the wifi in the shed, and I can still get 8mb/s and a very strong signal - which is surprising as there's a lot of building and garden in the way.

Of course I could always be tempted with one of the 10 other radio networks detected, of which 3 were open. Why do people do that?

Actually wouldn't do that. Unethical. And my bandwidth is just fine.

So I may not need the data cable. I agree that armoured cable is the way to go.

[michaelmorris]

The legal minimum safety requirements for outdoor permanent 240v mains installations is set out in Building Regulations Part P. Amongst other things this gives cable specs, depth of burying, protection measures and the need to have the installation certified by a suitably qualified electrician or by building regs department of your local council.

[Psychobilly]

Could alwasy used the mains cable to carry the netwrok connection and will get a lot higher speed than you will over the wi-fi that the way I am going to go if i ever allow the net back into the obs...

At the moment after a few muck ups caused by having the net in the obs and chatting or doing other things online i prefer to have it as a net free zone...

Peter...

[michaelmorris]

Could alwasy used the mains cable to carry the netwrok connection and will get a lot higher speed tahn yo will over the wi-fi that the way I am going to go if i ever allow the net back into the obs...

Peter...

Peter that's exactly what I've got. It works a treat and connection speeds are the same as via a normal network cable. Installation was the simplest the simplest thing I've ever done on a computer. Plug in your computer into one adaptor and your broadband router into the other - that's it! No software, no drivers, no set up - nothing.

The system is called Homeplug. Home - HomePlug Powerline Alliance

and comes in 14 mbps, 85 mbps and 200 mbps speeds. A 85 mbps two adaptor system (for one computer and one for router) starts from around £40 and a 200 mbps system from around £65.

I gather they won't work if one or both of the socket has surge protection, although i've never tried this. Some websites say that signal degradation caused by the multitude of fuse boxes within some outdoor building electrical installations means that a home plug system may not work in these circumstances. I bought my system from PCWorld who had no problem agreeing to me bringing back the hardware (with original packaging) and getting a full refund if I couldn't get the system to work in my observatory.

[Beyond_Vision]

One thing to remember with the HomePlug system is that the various speed devices are not comaptible with each other. In other words they are not backwards compatible. Although the various speed devices can co-exist on the same mains wiring.

Regards

Kevin

[michaelmorris]

One thing to remember with the HomePlug system is that the various speed devices are not comaptible with each other. In other words they are not backwards compatible. Although the various speed devices can co-exist on the same mains wiring.

Regards

Kevin

My understanding is that the 14 mbps and 85 mbps systems are cross compatible, but that the 200 mbps is not. FAQ's (Frequently asked questions)

[Beyond_Vision]

Thanks for clearing that up Michael. . The big problem is that if you want a 200mbps link to the router you need a 200mbs device pluggged into it which then is not comaptible with a 85mbps or 14 mbps device elswhere on the network. This would meam that another port on your router taken up with an 14/85mbps device which you may not have spare.

Regards

Kevin

[Jarndyce]

Very informative, gents. Thanks for that. My father recommended the same approach.

I'll probably end up running an armoured cable through a plastic conduit above ground. I can fit it to the gravel boards along the fence. There is then absolutely no chance of putting a fork through it.

Rather than run it from the mains board, I can attach it to an RCD on an IP55 (or is it 65?) outside socket that I already use for lawnmowers etc.

Have any of you guys with obs insulated the walls/roof of your building?

[Psychobilly]

check this out hmmmm.....

[brianb]

Could alwasy used the mains cable to carry the netwrok connection and will get a lot higher speed than you will over the wi-fi

If you're burying a mains cable the extra cost & effort involved in burying a Cat 5 ethernet cable at the same time is so small as to be entirely negligible. Keeping things seperate is a Good Idea (especially if anyone within a couple of hundred metres likes to listen to the radio) and the reliable bit rates on cabled ethernet makes wifi look like a bad joke.

100 megabits/sec full duplex over 100 metres is normal.

[Psychobilly]

I had thought of insulating the walls then remebered that ideally you want the inside temp and the outside temp to be as close as possible.. ok when you open the roof etc it will cool but you'll have thermal currents... more so if you use the scoep through a narrow viewport...

My white plastic obs hold a differential of about 1 C inside to out even when closed up during those rare bright sunny days...

Peter...

[daryl_lincoln]

The legal minimum safety requirements for outdoor permanent 240v mains installations is set out in Building Regulations Part P. Amongst other things this gives cable specs, depth of burying, protection measures and the need to have the installation certified by a suitably qualified electrician or by building regs department of your local council.

Just on the point on certification, if you are going to add to a existing circuit then just be aware that if you dont have a electrical instalation certificate (lasts 10 years in a domestic property) or a current periodic inspection report (also last 10 years). If that circuit doesnt conform to the 17th edition wiring regs (BS7671), Then this circuit would have to be brought up to 17th standard.

I have upset many people by saying that it going to cost say, £400 to get a certificate, as they need extra work done.

If you are not confidant that this is the case,then if possible then put it on its own cuircit from the mains board then only this circuit will require documentation.

Daryl

[Psychobilly]

Hypothetical question....

What if....

You use a junction box to terminate the armoured.. and then use a flex fitted with a 13A plug to make a temporary connection to an existing Ring main using an RCD adaptor?

[Jarndyce]

You use a junction box to terminate the armoured.. and then use a flex fitted with a 13A plug to make a temporary connection to an existing Ring main using an RCD adaptor?

That's what I intend to do, Peter. Essentially an armoured extension lead.

I know loads of people with power in their sheds. Haven't come across a single one that's been certificated or inspected.

[daryl_lincoln]

Hypothetical question....

What if....

You use a junction box to terminate the armoured.. and then use a flex fitted with a 13A plug to make a temporary connection to an existing Ring main using an RCD adaptor?

If it was fitted with a pluged into a socket no certificate would be required as it would be classed a portable equiptment, same as your kettle say

As you suggest the reasonable way without getting into certification,would to be fit a switched RCD fused spur below a socket and put a 2.5mm flex with a plug on and feed the spur this way.

Then in the future if you ever have any electrical work done which requires certification, you can hard wire it before they test, then the work and the obs would also be included in the certificate

Imho then within the next 10years when you come to sell a house then a electrical certificate will be included within the HIPS (they a waste of money Imho) Which means more work for me at £200 a test

[Psychobilly]

Dont get me started....

[michaelmorris]

The 'stick a plug on the end of it and call it a temporary installation' approach is exactly what I've done. I went one further, the temporary cable is in fact very heavy duty flex (2.5mm artic flex if I recall). This runs through a single unjointed run of very heavy duty polypropelene pipe buried 30-40 cm below ground level with a layer of 'electricial cable below' warning tape 10cm below the surface. It has a high-end RCD built into the socket at the plug end.

[Psychobilly]

The "armoured" extension lead approach seems a sensible one to me and much better than the "normal" extension lead I had cable tied to the fence and draped along the hedge line for the "winter"...

You wouldn't want to run a permanent install to a temporary structure anyway

Peter...

[Jarndyce]

There appears to be a consensus of sensible opinions here...

[daryl_lincoln]

There always ways round all the reg's and just remember when you move the obs will go to so the only person that could hit the cable is you anyway any domestic electrical questions im always here