Clipsal Dimmers only 1amp. safety?

Hello,

I need an advice from an expert/electrical engineer. Clipsal Dimmers are only 1Amp, thats mean 240-250Watts maximum. let's say that we have a load of 240W and a shiort circuit appears on one of the transformers or a single lamp. is there any protection on the dimmers or the dimmer will be burned?
Waiting for any usefull advice.

Thanks in advance

 

The 1 amp dimmer (and the 2 amp version) come in the plastic din rail format. The 1 and 2 amp dim capacity is largely to do with the heat dissipation capacity of this physical unit arrangement. Secondly is the fact 1 and 2 amp loads line up well with typical groups of lights you would encounter in domestic and light commercial applications.

In the case of a "dimmer" channel and short circuit fault there is one answer- say goodbye to the dimmer channel. If you have a bit of time available you can pause for a moment of silence out of respect, but thats all you will be able to do.

Don't worry about circuit breakers or fuses to protect the dimmer output stage - the triacs in the output are a bit stronger than those used in the early days and they will take a good bit of overload and short term abuse, but a good short circuit is time to start waving goodbye to that channel...

 

According to the trainer at Schneider it is a requirement to provide protection to the output stage via an MCB device in order to maintain warranty for installed kit. Its a bit annoying as the breakers are not cheap at that level. All my setups have breakers on the output, should prevent problems on big shortouts, there is an argument that the triacs would burn out quicker than a breaker can trip though.

 

Here in Aus it is not a requirement to have circuit breakers installed on the load circuit. Some people do install for "additional" safety, namely to protect the cabling during a major failure of equipment and to isolate a circuit to change a fitting etc. The first reason doesn't make that much sense to me because the load side cabling should be rated to the same level as the supply to the dimmer unit... So having circuit breakers on the load side of a dimmer (up to 10 amps) seems like a bit of a waste of money, space and time to me..

From what I have seen the best practice is to install a circuit breaker per dimmer unit (supply to the dimmer) plus a 970RMT overvlotage arrester for the lighting supply. A really good intsall uses the remote monitor 970RMT - connected to a security system or even a bus coupler and CTouch to let you know the arrester has done its thing.

 

When you say that the capacity is "largely" to do with the heat dissipation, does that imply that they can be over loaded fairly safely provided adequate ventilation?

In my installation I have two dimmer channels that are each driving four 240v downlights (one channel has 4x R80 globes, and the other 4x R63 globes). If I were to put 100W globe (or even 75W for that matter) in, would I be pushing the dimmers too much?

Does the load on the dimmer depend on the amount of dimming? Ie, is there more or less load when the lights are dimmed or on full brightness? My educated guess would be that the dimmer channel is stressed more when its dimmed low.

 

In my installation I have two dimmer channels that are each driving four 240v downlights (one channel has 4x R80 globes, and the other 4x R63 globes). If I were to put 100W globe (or even 75W for that matter) in, would I be pushing the dimmers too much?

They are rated at 1A for continuous operation. R63 only come in 60W, so that is 240W total and right on 1A (at 240V of course)

R80s come in 60, 75 and 100W. 4x100W is definitely too much. 4x75W = 300W which would probably be OK for a while.

I did a job where an electrician connected 2 x 300W uplights onti a 1A dimmer channel and it survived. But that channel was not used continuously, as the house was not yet occupied.

If you need more light, then change from 60W R80 to 50W Halopar20 - you get more light, double the lamp life and save some power as well!

 

I've had the same recommendation, but experience has proved otherwise. I had a dead short and fried the dimmer channel in the time it took the breaker to trip. Unless you're using highly sensitive breakers (v.expensive to add one per channel too) then there's not much you can do but observe that moment's silence.