newbie load question

Hi,

I have been researching CBUS and have gotten lots of information from this forum. But there are some questions I would like to get full clarification.

If I have a L5512RVF that has 12 channels with 10A, does that mean that on 1 channel, it supports 10A. Therefore if 1 light that is 50W at 240V, it will use 0.2A. So I can drive 50 lights from 1 channel?

How safe is it for me to use up the full 10 Amp, and how much should I leave as a buffer (from professional experience)?

Also, if I used LED downlights instead that only uses 10W, I can drive 25 LED lights per channel? L5512RVF uses relay, is there any problems using LEDS on the relay?

Also, if I used a dimmer L5508D1A instead, which has 1A per channel. So I can only have 5 x 50W lights per channel? I have read many posts about not being able to use LEDS on dimmers, apart from the starburst or prompton XL LEDS. The starburst use 16W, so I can have 15 starburst LEDS on 1 dimmer channel? Is there anything else I need to do or add to get this to work?

 

Welcome to the forum!

Yes, each channel on the unit supports 10A of load. 240V @ 10A = 2400W total. If your loads are genuinely 50W then you could connect 2400W / 50W = 48 lamps to that circuit. If you're talking about low-voltage halogen lamps the actual figure would be a bit less, as you need to allow about 5W extra (rule of thumb) for the associated transformer losses. It's also worth remembering that 50W halogen lamps will be banned soon, so it may be worth thinking about the 35W IRC lamps which won't be banned just yet.

Clients always ask for changes to be made and can get cranky when it costs them big $$$ to make simple changes, so I'd not load the channels up more than about 80%. More generally though, running so many lamps off a single circuit may, depending upon your install, start to defeat the purpose of having a system like C-Bus that enables lots of different ways to control the system. Having lots of individual circuits, and then setting Scenes, enables lots of different lighting moods to be created. Just grouping all the lights together and turning them all on and off in one lot may be limiting in the future and result in you missing out on some of the benefits of a controllable and configurable system like C-Bus.

This is also fine, but again make sure you allow for transformer losses and future expansion. You could connect a lot more than 25 LED lamps @ 10W each to an L5512RVF channel.

No, it's not that simple. Pierlite publish an approved dimming systems chart for the Starburst LEDs which you can find here. As you can see, you can install a maximum of 6 Starburst LEDs on the L5508D1A (or L5504D2A), but up to 36 Starbursts on a L5504D2U. Some of the Clipsal Infinity dimmers (not shown in the Pierlite chart) allow over 100 Starburst lamps per channel. Leading edge dimmers don't really like capacitive-type loads, so the limit is more complicated than just a simple calculation of power figures.

 

yulp... sorry brain freeze, 250 LED lamps @10W each. Wow... But if I wanted to connect this many to the circuit, it's ok?

Thanks... So no problems with connecting LEDS to relays, just calculate the max load and work off that. But with dimmers have to take into account the capacitance and manufacturers documentation. Thank you.

Those starbursts are quite expensive, from reading other forum posts. It appears they are exactly the same as the crompton XLs.

Is it better then to have multiple LED channels, and turn on more channels to make a room brighter?

 

It will probably be a bit less than that. The power factor of some of these LEDs can be quite poor and that can reduce the number you can safely put on a channel, but it's still going to be an awfully big number.

I'm not entirely sure I understand what you're asking here. If you need to have lots of dimmable LED lamps on a single circuit then you really should be using a universal or trailing edge dimmer, enabling you to have heaps on a single circuit. If, for some unforseen reason, you have to make the LEDs run from a leading edge dimmer then you can split them in to multiple circuits and assign the different circuits the same C-Bus group address, making them behave as if they were just one big circuit.

Again, I'd suggest that unless the space you're lighting up is the MCG, dividing up your lighting in to different circuits will give you lots of flexibility with how the system is used. You can easily and cheaply re-program C-Bus at any time, but changing the way things are wired is a lot harder to do later.

 

Thank you newman... your responses have been very helpful.