Hi, have put in first fix wiring for 8 GU10 50w recessed spots in the ground floor ceiling, daisy-chained from the junction box with 1.5 mm cable. Only when I glance at the instructions for the lights do I read that the manufacturers advise no more that 5 be daisy-chained together. My rusty school physics suggests that A = W/V, means load (amp) =
1.666A, which shouldn't be a problem. Would someone kindly point out what I'm missing, as I'm feeling very thick!Cheers,
Tom
Your calculations are correct.
8*50w = 400w 400w / 240v = 1.666A.You can now expect:
1) Pedants to tell you thet the mains voltage is 230v ( which it isn't ); 2) A host of Tokenist Greenies to berate you for not using CFLs.Feel free to ignore both of them.
( But do consider whether the 8 spots will give the required coverage. They tend to give a rather fierce 'projector' glare at one point, leaving the rest of the room dark in comparison. They don't make for good general lighting, unless you use lots of them. There are circumstances where this works well, and those where it doesn't. This will incurr the greenies wrath, as you will soon see, and worse, you will be changing the damn things every other day. )
There may be wiring regulation issues that come into play, others will advise.
It is more of an issue with GZ10s (i.e. 12V), where the current is correspondingly 20 times higher, and a small drop in voltage tranlates to a much bigger visible difference in light reduction.
My mains voltage as I type is 228.9.
Is that pedantic?
In article , Vortex writes
246.6 here!..
I wonder if you can purchase some kind of cheap device for logging mains voltage against time.
18:00 to 20:00 in Winter our mains voltage is 215-220Summer daytime it's 240V
There are an awful lot of I-squared-R's going to wastee in transmission losses out there.
Something to investigate.
In article , vortex2 writes
That will be the supply impedance of the line and transformer supplying you.
Most UPS units have some voltage logger and event recorder built in which show quite wide variations sometimes more that the permitted ones but getting the distribution companies to do something about that is like banging your head 'agin a brick wall!..
FWIW the software that came with my UPS does this 24/7 on the server. I really CBA to even look at it.
If you have an APC Smart UPS the software records voltage amongst other things and presents it on a nice graph. It's probably possible to get the recorded figures from a log file to export and keep as a voltage log.
Alan.
We had a weird power thing the other day. Mains voltage dropped to 63 volts and stayed like that for several hours. I turned off as many things as I could find - luckily nothing seemed to be damaged. Interestingly, one of my computers kept going for quite some time before it gave up!
Tom I have linked 18 GU10's but used 20W bulbs in them instead of 50W's, room size is 4m x 7m ceiling height is 4m (yes very high), I have experimented and the best amount of light produced in my case is with only 10 lights opperational giving a total of 200W.
Hope this is helpful.
Calum Sabey (NewArk Traditional Kitchens 01556 690544)
In the last 7 days Minimum 230v Maximum 257v
Although pricey at the moment there are LED GU10 lamps which are getting pretty good now in terms of light output. Look at Lyco's website.
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