1000watt dimmer switch buzzing and over heating

[Paulblackford]

I recently got my house re-wired and in the lounge I have two sets of low voltage (24v) spotlights. One circuit has 12 x 50 watt bulbs (600w) and the other circuit has 6 x 50 watt bulbs (300w).

I designed it this way on the back of buying a 2 gang 1000watt dimmer switch which states that each gang can take a minimum of 150 watt and a max of 1000 watt.

However when we did the big switch on both switches give off a very loud buzzing noise (too much to live with) and in fact the smaller load 300 watt switch gives off an even bigger buzz and after 10 mins the light starts to flicker and a burning smell comes from the switch.

I first thought it was a faulty switch and the supplier sent me a replacement free of charge - but when we switched it over it still has the exact same problem.

All the other circuits upstairs were wired the same way (transformers with each light) but with lower loads (up to 300w) and all work ok off standard dimmers - Can anyone explain? Do i just have a cheap 1000 watt dimmer as it was off ebay or is there a bigger under lying problem.

Problem is house is now all decorated nearly and not simple to run another cable

All help will be much appreciated

 

[riveralt]

First of all you should get the electrician back who did the rewire to properly design the lighting circuit'
What size cable did he/you design for this circuit?
Do both of these circuits come from one MCB and if so what other lights are on that circuit?
Most dimmers need to be downrated for GU10 lamps sometimes by more than 30%. The closer you are to the maximum the louder the buzzing will get. Also some dimmers require the lamps to the fused.

Are you sure that the dimmer is 1000w for both gangs - the burning smell should perhaps suggest that this could be the total wattage allowed.

Why on earth do you need nearly 1 kw of lighting power for the lounge - do you not have central heating?

 

[ban-all-sheds]

Why on earth do you need nearly 1 kw of lighting power for the lounge

I can think of two reasons.

1) His lounge is the size of a footie pitch.

2) In braindead style he has decided to try and light up the room by using lights which are deliberately designed to not light up rooms.


If the latter, I wonder what other lies the person who did the work told about its compliance with the Building Regulations?

 

[JohnW2]

What size cable did he/you design for this circuit?

Whilst I agree with everything else you say, can you help me understand what this question is about? Assuming we're talking T&E, 1mm² is obviously the smallest available, and even that would be more than adequate for the load described.

Kind Regards, John.

 

[riveralt]

What size cable did he/you design for this circuit?

Whilst I agree with everything else you say, can you help me understand what this question is about? Assuming we're talking T&E, 1mm² is obviously the smallest available, and even that would be more than adequate for the load described.

When taking the C&G2391 practical I was taught in tryng to identify faults to assume nothing -you should do the same.
Gather all the relevant information first then make an assessment.
We don't have all the relevant information.
The OP has stated that a burning smell was coming from the switch - since according to the OP the switch while buzzing, was within load and not faulty then the only other possible cause for the burning smell is the cable.
If the cable is 1mm2 T&E and correctly terminated, the MCB is 6Amp and the total load does not exceed the current carrying capacity then despite what the OP has stated we should take another look at the dimmer.
Additional questions might also be asked regarding the lamp units themselves - but one step at a time.
I don't understand why you don't understand why the question was asked?

 

[JohnW2]

I was taught ... assume nothing ... Gather all the relevant information first then make an assessment. I don't understand why you don't understand why the question was asked?

I suppose because the 'worst' possible ('credible'**) answer (1mm² T&E) would not really have had any bearing on my (and I wouldn't have thought anyone else's) views or responses to the question. So, whilst I agree that one should always gather all relevant information, I wondered if I was missing something which made this information relevant. **I presume you must have been considering the possibility that the lighting circuit had been wired in, say, bell flex or Cat5e cable, and I suppose I cannot cricise anyone for considering the incredibly improbable - crazy situations do exist.

In fact, talking of relevant information, the one possibly relevant bit you didn't attempt to gather was the In of the MCB/fuse.

Kind Regards, John.

 

[RF Lighting]

I've never seen a double dimmer that can take 1000W on both gangs. Normally 1000W dimmers have a dimmer module which is much bigger than a normal 250W / 400W.

 

[333rocky333]

I've never seen a double dimmer that can take 1000W on both gangs. Normally 1000W dimmers have a dimmer module which is much bigger than a normal 250W / 400W.

Ive replaced a few 1000w single size modules, there usually cheap tat,

 

[RF Lighting]

I think we've solved the problem then

 

[Taylortwocities]

I have two sets of low voltage (24v) spotlights.

Are you sure about that?

 

[Paulblackford]

First of all you should get the electrician back who did the rewire to properly design the lighting circuit'
What size cable did he/you design for this circuit?
Do both of these circuits come from one MCB and if so what other lights are on that circuit?
Most dimmers need to be downrated for GU10 lamps sometimes by more than 30%. The closer you are to the maximum the louder the buzzing will get. Also some dimmers require the lamps to the fused.

Are you sure that the dimmer is 1000w for both gangs - the burning smell should perhaps suggest that this could be the total wattage allowed.

Why on earth do you need nearly 1 kw of lighting power for the lounge - do you not have central heating?

The dimmer with the lower load gives off the most buzzing and yes it is a very large lounge 45m2

 

[Paulblackford]

Other notes:

Cable was t&e 1.5mm

Dimmer states 1000 watt max and 150 min for each gang

What does fusing each light mean?

Make off dimmer is Richmond? apparently not a cheap make?

Downlighters are Robus - screwix ref 66950

On one circuit in fuse board along with 9 lights in kitchen which are split on to 2 standard on / off switches

 

[riveralt]

From your screwfix code number you have 12v downlights not 24v as you have stated - so each light will require a leading edge transformer as per dimmer manufacturers instructions.

Since you are using MR16 lamps these is no need to fuse them this applies to GU10 lamps and is a requirement for richmond dimmers.

You don't say which Richmond model you have - but the universal 2 gang dimmer has a max rating of 1000w per plate with a min/max per gang of 60/400w.
http://www.richmondlighting.co.uk/product/Universal_Economy

So you are exceeding the load on this part of the circuit for the dimmer and possibly exceeding the load on the circuit as a whole. You will also be destroying the dimmer.

As I said ealier you should get the idiot back who designed this circuit for you and tell him to do the job properly.
In the meantime the max lamp you can fit to each unit is 30watts.

 

[Paulblackford]

This is the dimmer switch I have bought and the supplier says that the 1000w rating is meant to be for each gang:

http://www.ashdownhomestore.co.uk/g...way-1000w-dimmer-switch-twin-plate-8615-p.asp

 

[riveralt]

This is the dimmer switch I have bought and the supplier says that the 1000w rating is meant to be for each gang:

http://www.ashdownhomestore.co.uk/g...w-dimmer-switch-twin-plate-8615-p.asp[/QUOTE]
Hang on you told us the make of the dimmer was Richmond - is this not the case now?
The trimline Design by G&H brassware only makes two gang two way dimmers up to a maximum of 400w - so you are snookered there as well and according to their website the TSN162 does not exist.

Having read the literature in your link I can see how you are coming to the conclusion that each gang handles up to 1kw of power but clearly that is not the case - especially as things start buzzing and get hot and smokey when you ignite (sorry) turn on the lamps. Think about it a minute you are potentially put through nearly 2kw of power through a dimmer - do you think that is wise or indeed feasible.
Even the website you purchased the product states:

"Overloading a dimmer switch (exceeding the maximum load) can result in buzzing, overheating, lack of dimming capability and possible dimmer switch failure." Does that sound familiar?

By the way I trust, well I don't really, that your electrician properley assessed the size of the MCB on this circuit.

As I said you before get the idiot electrician back to properly design the circuit. He has a choice of either rewiring the circuit to reduce the number of lamps on each circuit controlled by the dimmer to bring it within the manufacturers range or reduce the wattage of the lamps down to say 20 or 30 watts.