Advice on providing mains power.

[Ouroboros]

I don't have an observatory (it's a long term ambition) and I set up my telescope outside my 'warm room' (a shed) 30 metres from the cottage. I provide mains power to my shed on each occasion using a long extension lead passed through an open window to an inside socket. Permanent mains power would be safer and much more convenient.

Underground mains cable Is the preferred option, all electrical work would be carried out professionally. I'm not physically capable of digging a trench 30m to the shed (beneath grass) and some concrete, although I understand powered trenchers can be hired. So I would have to get a contractor in to dig it. I haven't sought quotes yet but I suspect this will be very expensive and I'm not sure I can justify the cost and disruption to the garden, let alone punching through the concrete that surrounds the cottage.

A simpler alternative is to get a qualified electrician to provide an outside mains socket. This would make using a temporary extension cable on each occasion much easier and would be useful to have anyway.

I don't know what the experienced 'electricians' amongst you would think of this idea, but I could (in principle) fix heavy duty external cable to a fence, which runs down the length of the garden adjacent to the shed. Then all I would have to do, when I wanted power to the shed, is to plug this cable into the proposed external power socket attached to the outside wall of the cottage.

Any thoughts? How have you done it?

[Tinker1947]

i'm not sure i would be happy plugging in or take a plug out of a external socket, it would need to be turn off from inside the property first (another core) if there's no RCA inside on the main fuse board this would need to be installed, i would have a outside weather proof double socket for convenience but not for a extension to your shed have a extra weather proof connection box and run the cable down the fence...your going get get a shed load of regulation thrown at you but a competent electrician will know whats what....

[Kropster]

" a shed load of regulation"........ or in this case, an observatory load, perhaps!   

[Mick J]

Possibly big and ugly, a waterproof box outside with a master fused breaker and a socket (and a red lamp), rubberised/armoured-cable clipped to fence with waterproof socket near where.  All this must be RCB protected.  

[daz]

I have been thinking about something similar, and I have come up with:

Inside the house:

Switched fused spur that feeds the external socket *

Outside the house:

Weather proof box

IP66 rated weatherproof socket mounted inside the weather proof box

RCD protection for the cable to the observatory

And then reverse the connections in the observatory - so a weather proof box that has an IP66 socket inside.

Then inside the observatory, RCD protection

Not sure regulations are involved as it's temporary structure, but it's been some years since I read the regs!!

* I guess, ideally, this would be on it's own fuse in the main fuse board....

[L8-Nite]

If I were going to have a temporary outside cable hookup, I would use the system that is approved in caravan parks.

[Skipper Billy]

Speak to a marine electrician - we run mains power out to boats - its a long lead plugged into a box on the jetties and into a box on the boat - both boxes are RCD protected. The boats are out in all weathers pitching up and down and rolling about and being connected and disconnected by wet through sailors and at our Marina no one has ever been fried in much tougher conditions than our back gardens !

[Ouroboros]

i'm not sure i would be happy plugging in or take a plug out of a external socket, it would need to be turn off from inside the property first (another core) if there's no RCA inside on the main fuse board this would need to be installed, i would have a outside weather proof double socket for convenience but not for a extension to your shed have a extra weather proof connection box and run the cable down the fence...your going get get a shed load of regulation thrown at you but a competent electrician will know whats what....

Yes, I was thinking of an external weatherproof double socket like the one you describe connected to its own output on the main fuse board, which is relatively new and has trip switches. I'd get this socket installed by a qualified electrician. What people temporarily connect to such outside sockets is not covered by regulation of course, but I obviously want to make sure it's safe in practice.

[Mr Spock]

I have an armoured cable running from the house to the patio I observe from. I drilled a hole through the wall near a mains socket for the cable to run through. I only plug it in when it's needed.

[Ouroboros]

If I were going to have a temporary outside cable hookup, I would use the system that is approved in caravan parks.

Yes, I'd thought of that. Perhaps I could have a weatherproof cable attached to the fence with one of those three pin plugs (sorry I don't know what they're called) on the end like caravans use, which I then plug into a socket attached to the external wall of the cottage.

[Ouroboros]

Speak to a marine electrician - we run mains power out to boats - its a long lead plugged into a box on the jetties and into a box on the boat - both boxes are RCD protected. The boats are out in all weathers pitching up and down and rolling about and being connected and disconnected by wet through sailors and at our Marina no one has ever been fried in much tougher conditions than our back gardens !

At least our observatories remain stationary .... although we're often at sea! Good point though. I wonder whether marine arrangements are similar to the caravan methods mentioned earlier?

[Tinker1947]

I use one of these on the side of the Obby it was in the open, its now inside the Dob House the other end goes inside my workshop into a RCD plugged into the ring main, this is only live when i'm in the Obby, the workshop supply is shut off when its locked up....

[Scorpius]

Another option might be - if you have a southern view - is to go with a small solar system dedicated to the shed/future observatory. The cost of solar panels has dropped significantly and you shouldn't need a huge system for a small garden obsy. The main components you'd need are a properly sized solar panel, a charge controller, a deep cycle battery or two, a power inverter & some cabling. The southern aspect is a must & you can also use a gasoline generator & battery charger to top off the batteries if you get a string of cloudy days.

I'm in the same situation of having to run an extension cord from my gazebo to my future obsy & will eventually be trenching in an underground cable, but even then the entire site will be powered by solar since I have no mains at this location. It's green, costs nothing to operate and works well as long as the power demands aren't huge - which I've found not to be the case for my equipment. You can even install some low-voltage LED lighting (they make red bulbs too) so you'll be able to see what you're doing while setting up.

Just a thought but if you decide on a mains cable along the fence instead, be sure to use outdoor, UV resistant wire and/or put it in a conduit. From a safety standpoint, it needs to be installed in a way to protect it from damage by lawn mowers, etc...

Here's a couple sites I found by googling UK solar panels:

http://www.sunshinesolar.co.uk/

http://www.theuksolarpanelshop.co.uk/diy-kits-assembled/

http://www.solarpanelsuk.co.uk/

[Ouroboros]

Another option might be - if you have a southern view - is to go with a small solar system dedicated to the shed/future observatory. The cost of solar panels has dropped significantly and you shouldn't need a huge system for a small garden obsy. The main components you'd need are a properly sized solar panel, a charge controller, a deep cycle battery or two, a power inverter & some cabling. The southern aspect is a must & you can also use a gasoline generator & battery charger to top off the batteries if you get a string of cloudy days.

I'm in the same situation of having to run an extension cord from my gazebo to my future obsy & will eventually be trenching in an underground cable, but even then the entire site will be powered by solar since I have no mains at this location. It's green, costs nothing to operate and works well as long as the power demands aren't huge - which I've found not to be the case for my equipment. You can even install some low-voltage LED lighting (they make red bulbs too) so you'll be able to see what you're doing while setting up.

Just a thought but if you decide on a mains cable along the fence instead, be sure to use outdoor, UV resistant wire and/or put it in a conduit. From a safety standpoint, it needs to be installed in a way to protect it from damage by lawn mowers, etc...

Here's a couple sites I found by googling UK solar panels:

http://www.sunshinesolar.co.uk/

http://www.theuksolarpanelshop.co.uk/diy-kits-assembled/

http://www.solarpanelsuk.co.uk/

Thanks for that idea. Well worth looking int. I had thought of solar at some point. It would be absolutely fine for everything except ... heating. I know, I'm a wimp. But a small oil filled electric radiator in the shed just lifts the temperature on the coldest nights from brass monkey to comfortably warm (ish). Also plugging in a hair dryer is indispensable when dew forms, although 12v warm air blowers are available I know. I will give this further thought.

[Ouroboros]

I use one of these on the side of the Obby it was in the open, its now inside the Dob House the other end goes inside my workshop into a RCD plugged into the ring main, this is only live when i'm in the Obby, the workshop supply is shut off when its locked up....

Looks good. Forgive me, have I got this wrong? If that's the power arriving at the obsy, is that a 'male' live plug with pins delivering power into a 'female' socket? Or have I got that completely the wrong way about?

[Tinker1947]

Looks good. Forgive me, have I got this wrong? If that's the power arriving at the obsy, is that a 'male' live plug with pins delivering power into a 'female' socket? Or have I got that completely the wrong way about?

I did have them the wrong way round when first installed, there as they should be now, maybe i should take another picture.....as for 12 volt hairdryers i bought one and it ended up in the dustbin.....

[fondofchips]

An RCD is essential, I had a spare one on my distribution box.  The cable needs to be 'mechanically protected' this means armored cable or a means of protecting ordinary cable.  I used 32mm waste pipe to protect mine, running along a fence (above ground) where I don't do any cultivating (digging etc) so it won't get damaged.  At each joint I used a 'T' piece instead of a connector to join the sections of pipe together, so there is a drain point every 3 metres.  The cable I used was some heavy 3 core cable kindly left behind by the previous occupants.   The waste pipe protects both shed and obsy cables, and the ethernet cable to the obsy as well.

If you want to run your power from a 13A garage socket, simply convert the front of the socket to a RCD protected one.  My other shed is run from one, a short lead to a junction box then the cable up to the shed running through the waste pipe.  This is then a semi-permanent extension lead protected by a 13A fused plug and the RCD in the socket.  Not exactly part 'P' compliant but the RCD and the 13A fuse should protect it OK.

If the cable is coming down to the point where the cable enters the shed then a loop is a good idea, the cable goes past the entry point and then up again.  If water runs down the cable it gathers at the bottom of the loop and drips off, away from the cable entry.

One point to note is that if you have the old type fuse box your electrical earthing system may not be up to safely supplying power to any external building.

You should not get anywhere near a 13A load, but I only have low power heaters in my obsy and don't use a kettle in there.

If in doubt contact a qualified electrician, and remember if the property is your own then any external wiring may have to be removed before you sell it again.  A qualified electrician should issue you with a compliance certificate to the current standard, then your wiring will be OK when you come to sell the property.

Cheers,

Fondofchips.

[Scorpius]

Thanks for that idea. Well worth looking int. I had thought of solar at some point. It would be absolutely fine for everything except ... heating. I know, I'm a wimp. But a small oil filled electric radiator in the shed just lifts the temperature on the coldest nights from brass monkey to comfortably warm (ish). Also plugging in a hair dryer is indispensable when dew forms, although 12v warm air blowers are available I know. I will give this further thought.

Certainly understand you don't want to dive right into solar at this point but it's worth noting the power inverter increases voltage to 120V AC (in the US) and you can still connect 12V LED lighting ahead of the inverter & get the best of both worlds. Problem with solar is high demand devices like hair dryers & heaters since any AC appliance with a heating element is going to need a lot of juice. Of course dew heaters don't fall under this category since all the ones I'm familar with are 12V. I've found my modest solar setup can handle an AC hair dryer for no longer than it's typically on but the oil filled electric heater would probably be a different story. I currently use a small LP gas heater with safety shut-off in my temporary shelter (pop-up tent) but realize that might put some folks off although modern gas appliances burn much "cleaner" than they used to and the tent door remains open for access to the scope. But a source of heat is something I'll definitely need to re-think once my obsy is up & running. Anyway, good luck whichever way you decide to go... 

Speak to a marine electrician - we run mains power out to boats - its a long lead plugged into a box on the jetties and into a box on the boat - both boxes are RCD protected. The boats are out in all weathers pitching up and down and rolling about and being connected and disconnected by wet through sailors and at our Marina no one has ever been fried in much tougher conditions than our back gardens !

Forgive my ignorance but just trying to get up to speed on UK terminology - RCD? Over here we call it GFCI (ground fault circuit interupter) 

If the cable is coming down to the point where the cable enters the shed then a loop is a good idea, the cable goes past the entry point and then up again.  If water runs down the cable it gathers at the bottom of the loop and drips off, away from the cable entry.

Great point & highly recommended - over here we call it a drip loop...

[Ouroboros]

I did have them the wrong way round when first installed, there as they should be now, maybe i should take another picture.....as for 12 volt hairdryers i bought one and it ended up in the dustbin.....

OK. Sounds more sensible. I wonder whether 12v hairdryers are much cop.

[Ouroboros]

Certainly understand you don't want to dive right into solar at this point but it's worth noting the power inverter increases voltage to 120V AC (in the US) and you can still connect 12V LED lighting ahead of the inverter & get the best of both worlds. Problem with solar is high demand devices like hair dryers & heaters since any AC appliance with a heating element is going to need a lot of juice. Of course dew heaters don't fall under this category since all the ones I'm familar with are 12V. I've found my modest solar setup can handle an AC hair dryer for no longer than it's typically on but the oil filled electric heater would probably be a different story. I currently use a small LP gas heater with safety shut-off in my temporary shelter (pop-up tent) but realize that might put some folks off although modern gas appliances burn much "cleaner" than they used to and the tent door remains open for access to the scope. But a source of heat is something I'll definitely need to re-think once my obsy is up & running. Anyway, good luck whichever way you decide to go... 

 Forgive my ignorance but just trying to get up to speed on UK terminology - RCD? Over here we call it GFCI (ground fault circuit interupter) 

 Great point & highly recommended - over here we call it a drip loop...

RCD - Residual Current Device. A trip switch in other words.

Good point about dew heaters. We can buy LP gas heaters with catalytic converters to make them safe for indoor use without a flu. They're not recommended for wooden sheds though.

[Ouroboros]

Thanks to all for your helpful ideas and suggestions. The next step is for me to get in a qualified electrician to discuss options and get some estimates on cost. As a minimum I will probably get the electrician to install external weatherproof sockets, which will be useful anyway for power tools in the garden. I like the idea of a caravan-style hookup. It's something I can do myself in a semi-permanent arrangement and I think it's inherently safer and more convenient than what I'm doing now.