EFLI And Dimmers

[securespark]

Anybody had any problems with the above?

 

[RF Lighting]

Yep, all the time.

Especially big ones in theatres, even if they are set to maximum output.

We link the dimmer circuitry out whilst doing the Zs test.

 

[Spark123]

Yep, as a dimmer electronically alters (clips) the sine wave I imagine it will play havoc with the reading on a tester. Attempting to drive 23A or so through a triac will probably not do it any favours too.
Either do as RF suggests or just use Zs = Ze + (R1+R2) method.

 

[securespark]

Phew!

I was talking about domestic kit, but I suppose the principal is similar.

I have never experienced this before.

I was changing a pendant yesterday. Powered up and did the Zs.

>1999 on the Alphatek. Yikes, thinks me, we've got a case of broken continuity on the cpc.

Luckily, a colleague was with me and he tried it using his plug in lead with a flying lead for the earth: http://isswww.co.uk/Accessories/Alp...h-bond-Wander-lead-for-use-with-Metrel-range/

With this, he got 0.83 Ohms. We tried my method with his Alphatek & leads: >1999.

Then I rang our technical guru and he said that loops are not possible from dimmer-controlled fittings because the triacs limit the flow
of test current & this is why the reading comes back open circuit.

I did look at the dimmer and it was one of the huge old-fashioned ones (those that take up the whole back box, not just a small module), so I guess that made a difference.

This is the first time ever I've had a problem taking a Zs from a dimmer-fed light. Mind you, all the others have been modern dimmer modules. As long as the dimmer is turned right up, I've never had a problem.

It's true what they say: You never stop learning & I don't mind admitting I've learnt something from that episode!

Thanks Rob!

 

[securespark]

Sorry, numerical. I missed your post as I was typing up my reply to the Robster ( ).

I'm not sure that the Alphatek test current is so high. I never have a problem with it tripping breakers. Seem to remember it's only milliamps? Rob, do you know?

 

[Adam_151]

Its certainly not the 23A that old robins, etc used to pull (which not only took out 5A mcbs, but also on occasion 5A 3036 fuses as well!)

Its more than a few milliamps though on the proper loop range (its the triplock range only that uses a few milliamps- and I find its accuracy is often quite a bit off as a result)

I have the feeling it might be somewhere around 10A or so, you can certainly get a crackling from the contact points if you haven't made a good contact

An yes, ELFI testing on a dimmer is ill advised, anything less than full brightness will confuse the meter, and even then depending on what rating triac is in the dimmer and what test instrument is used, its possible to cause the traic to fail (usually in the on state)

Supprised you got >1999 though...

 

[securespark]

It was a very old, bulky dimmer circa 1970's. The ones with a very large knob (ooh err missus!) with a dimple in it.