2 way dimmer circuit

[stella321]

I am trying to replace one 2-way light switch with a new 2-way dimmer, preferably at the remote end of the circuit. The 1st attempt caused the dimmer to fail possibly due to 300W load on a 250W dimmer? The 2nd attempt with a 400W version still failed and apparently blew the dimmer again. The instructions only show the dimmer installed with the supply feed L1+L2 and not just remotely connected at the 3-core+E end?

Is this normally the case?

Why are the dimmers failing, are they that sensitive?

 

[timtheenchanter]

is it a halogen load?? IIRC standard dimmers need twice their rating for halogen, ie 300W halogen needs a 600W dimmer.

if they are halogen, mains or 12V?

 

[Steve]

What brand of dimmer? Some require the otehr switch to be a special type.

 

[stella321]

is it a halogen load?? IIRC standard dimmers need twice their rating for halogen, ie 300W halogen needs a 600W dimmer.

if they are halogen, mains or 12V?

The chandelier has 5 x 60W tungsten candle bulbs ie 300W load

 

[stella321]

What brand of dimmer? Some require the otehr switch to be a special type.

They are made by CED and supplied by Toolstation.com

 

[Steve]

Just been on toolstation for info, but there is none. It appears to be a bog standard dimmer. I'm thinking you're connecting it wrong.

What cores do you have at the switch position you're at? Accompany this with a photo if you want (for close ups, use macro focus <picture of a flower on most cameras>).

The other switch which controls the same light, tell us what is connected there also if you can.

 

[stella321]

Just been on toolstation for info, but there is none. It appears to be a bog standard dimmer. I'm thinking you're connecting it wrong.

What cores do you have at the switch position you're at? Accompany this with a photo if you want (for close ups, use macro focus <picture of a flower on most cameras>).

The other switch which controls the same light, tell us what is connected there also if you can.

At the box with the feed I have a twin+E, which is the switch feed and return, and a 3core+E for the 2-way strappers. At the other end, just the 3core+E, but somebody has expended the circuit as I have old and new colours on the 3core! I belled them out and discovered the yellow+blue out of sync with the new black+grey. I was totally confused because I thought as long as the common was the same L1+L2 being crossed wouldn't matter. But obviously on the new dimmer, this is critical?

Why aren't the dimmers protected by diodes in case of reverse polarity? Seems you only get one chance to get it right first time and I've blown qty.2 new dimmers already!!!

Will be returning to the job on Monday with dimmer no.3, any tips to avoid further disaster - DO TELL

 

[Steve]

Dimmers can be connected to the live and switched live either way around. But connecting L and SL to other terminals may cause problems.


HOWEVER, if the L and SL (feed and return) have been connected to L1 and L2, as opposed to C and C(second switch), you cant use your dimmer in this configuration AFAIK.

You would have to rewire it so you have two strappers between L1s and L2s, and the Live to C1 and the SL to C2.

 

[stella321]

Dimmers can be connected to the live and switched live either way around. But connecting L and SL to other terminals may cause problems.


HOWEVER, if the L and SL (feed and return) have been connected to L1 and L2, as opposed to C and C(second switch), you cant use your dimmer in this configuration AFAIK.

You would have to rewire it so you have two strappers between L1s and L2s, and the Live to C1 and the SL to C2.

Now you see why I am confused!

Are you saying I can only install the dimmer at the 2-core feed+return position and not at the remote 3core only side?

What is AFAIK (excuse my ignorance)?

 

[ban-all-sheds]

Dimmers can be connected to the live and switched live either way around. But connecting L and SL to other terminals may cause problems.

Why?

HOWEVER, if the L and SL (feed and return) have been connected to L1 and L2, as opposed to C and C(second switch), you cant use your dimmer in this configuration AFAIK.

Look at the diagram in the bottom left of the first image here: //www.diynot.com/wiki/electrics:two-way-lighting, i.e. the traditional way of wiring 2-way switches with a 3-core strapper.

Whichever end you put the dimmer, the current path always ends up going between C and L1 or L2. It must do, as no path ever exists between L1 and L2 on an ordinary switch, so if it works with ordinary switches it must work with dimmers (only one dimmer, obviously...)

You would have to rewire it so you have two strappers between L1s and L2s, and the Live to C1 and the SL to C2.

No.

 

[ban-all-sheds]

Now you see why I am confused!

Yes - confusing, misleading and incorrect advice, I'm afraid.

Seriously - if you invest a bit of time in studying the wiki article, and coming to understand how 2-way switching works, you'll be able to connect your dimmer at either end. No matter how it is wired, a switch ONLY provides a path between C and L1 in one position and C and L2 in the other, just like the dimmer does.

What is AFAIK (excuse my ignorance)?

As Far As I Know.

 

[stella321]

Many thanks, I do know how and what a 2-way lighting circuit looks like, being a spark of 25yrs experience, but this dimmer scenario really had me beat, normally you don't even think or expect such a problem to occur.

So how am I managing to damage the dimmer switches, surely you would think they would have some sort of internall protection?

Fortunately Toolstation.com have replaced the "faulty" dimmers!

 

[Steve]

Read the instructions for 2-way dimming that accompany the dimmers. They may require a different switch at t'other end o't'circuit.