There should be enough long leads at the star camp in Nov to run a test for you. I expect130m to be no problem with voltage drop.
RCD = residual current device = residual current circuit breaker = earth leakage circuit breaker = safety switch. I think you can buy power leads with one fitted. You should start with that one at the house. Even a good idea to use it for short distances since you have cables and connections exposed to the moisture etc.
Got to be 3!
It depends on your exact situation, but perhaps 'break-ins' can be partly solved by an alarm system, or planting some sort of vegetation - or make some other structure - that 'hides' the observatory.
Good luck! Hopefully next year I'll have similar choices to make, so I'll be asking you for help!
I have an excellent Burglar alarm!!!!
Can't hide it with bushes, it is all open clear land that can be seen easily from the road. A clump of bushes would look more conspicuous than an obs
Have we worked out your total load in amps? Let's do that.
We need to get the cheapest big roll of mains cable we can get that will reach from home to observatory. We put an RCD plug on one end and a socket on the other. We get a garden hose reel and you run it out each night as you want to use it, then wind it all back up the next morning.
Now, if we can guarantee your load will not exceed the cable specification, we might be able to use 8Amp cable (or l5Amp, if it is available) to save weight and space.
Just thinking aloud. All electricians on the site, please ignore this post!
option 3, absolutely. I run the red (outdoor) extension 15 m loose on grass, they use it on construction sites, tough as. Been there a year, no problem. The drop over 130m is no problem for your use. This is not the safest option, not good if you have kids or animals, can you string it on poles?. And DEFINITELY use an RCD trip.
Just checked the prices of rolls - 100m max and around $2.45/m. I bought 30m extn cable from Bunnings for $20 as I recall. Cheaper to buy four extn cables.
If there is a risk of damage (sheep nibbles), I still recommend rolling up after use.
Ken, 130 metres is nothing @ 240V provided you don't want to run a 2Kw heater or similar large load. I've just measured the loop resistance of a cheapo 20 metre, 10 amp Xtn lead and it's well under 1 ohm. I'm not sure of the resistance of typical 10-15 amp extension cords but I would imagine that they're probably going to be under 5 ohms for the distance. At 2 amps load (500Watts) that equates to around 10 volts drop, you're not even going to notice it, as a percentage that's only 4% . Your laptop and gear at most would draw half an amp (around 125 Watts), the voltage drop at that current would be negligible (around 2.5 volts.). At 12 volts it's a different story, resistance causes the same voltage drop but as a percentage the drop becomes significant, so stick with 240V and you will be sweet. We recently ran a catinery wire with 90 metres of extension cord for over 2 years outside in the rain, hail and shine, as a temporary supply for a Wireless Access point, no problems whatsoever, although the WAP's power consumption was only 15 Watts.
RCD's work by detecting any current imbalance between the 240 Volt neutral and active feeds and earth. If there is any more than a few tens of milliamps difference (they come in different current trip parameters) they trip the feed. I'm fairly sure I saw one for around $12 in Bunnings just recently.
I didn't understand a word of the Watts, ohms, amps, etc but it's good to know that I will be able to run 8 x 240v items at once with 130m of extension leads.
I will probably put them up on poles to keep them away from the sheep. Easier than digging a trench!
Oh, and I'll get a power surge thingy
If I can, I'll buy one extension lead each month. It'll take me a while to build the obs, so I won't need power up there yet.
Which is better? 10amp leads or 15 amp leads? (depending on prices too)
RCD Ken not surge thingy, if you ask for a surge thingy, it's likely the fool behind the counter will give you a surge thingy and not an RCD......
There's probably not much difference between 10 & 15 amp leads, but if the cost's not too great, I'd go for 15 amp as they're likely to be lower resistance.
RCD Ken not surge thingy, if you ask for a surge thingy, it's likely the fool behind the counter will give you a surge thingy and not an RCD......
There's probably not much difference between 10 & 15 amp leads, but if the cost's not too great, I'd go for 15 amp as they're likely to be lower resistance.
Oh, OK Phil. Thanks. An RCD
I bought a 30m 10amp lead from Bunnings last year. It was only $9 !!!!!
It appears that the vote is unanimous. The Obs will go waaayyyy up the back paddock in the nice dark unobstructed sky.
I will run power leads with an RCD at the House end. The leads will run on power poles until near the obs, then I will run it underground for the last bit so no poles or power lead obstruct the view.
also get an intruder alarm ;-). Its up to you, some may dissagree, but id get the outdoor grade extension (comes in bright colours depending on grade, red, yellow etc) they are UV and weather reistant. I think indoor lead will deteriate quickly in the sun and weather. Check the prices.
Yep, got one. It is the one that causes pain. The sound is designed to cause severe pain and Nausea. Even ear plugs don't stop it coz the sound wave is at a frequency that goes right through your skull!!!
It works, coz I have accidentally set it off and I had trouble turning it off even with the control in my hand. I felt very sick afterwards.
I had it in my Harley-Davidson shop and the Insurance company loved it
Quote:
Originally Posted by Bassnut
Its up to you, some may dissagree, but id get the outdoor grade extension (comes in bright colours depending on grade, red, yellow etc) they are UV and weather reistant. I think indoor lead will deteriate quickly in the sun and weather. Check the prices.
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