I am building a power diverter according to this diagram: Learn | OpenEnergyMonitor
If read the diagram correctly, there has to be 2x 10n capacitors. Does the value of the capacitor has to be exact, or something 100n would work?
Please advise,
Yes the capacitor does have to be 10 nF. And no, you did not read the diagram correctly. Only one capacitor is shown, and that is correct. It is X2, not × 2. X2 relates to the capacitor’s rating and its behaviour under fault conditions due to its position in the circuit (directly connected line-neutral, or maybe line-line for you, when the triac is off).
100 nF will give you a higher leakage current. The component values came from the manufacturer’s data sheet, I think you can safely assume they know what they are doing.
got it regarding capacitor being 10nF. Can you please elaborate more on X2? can I use any ceramic disk capacitor (actually 4+4+2 that I have laying around)? or does it has to be something like this: http://www.ebay.com/itm/20Pcs-0-01uf-0-47uf-10NF-470NF-275VAC-275V-10MM-X2-Polypropylene-Film-Capacitor-/192142398031?var=&hash=item2cbc94524f:m:mKofh_2l65WC0g3NyoKVgNw
This Film capacitor - Wikipedia seems to tell you just about everything you might ever need to know about capacitors. Note that snubber capacitors and RFI suppression capacitors have special mention - yours performs both roles.
I wouldn’t trust a capacitor in that position from an unknown maker - even the brand name is pixellated out - it is worth spending a small amount more for a reliable device from a reputable distributor: http://www.alliedelec.com/passive-components/capacitors/?navigation=4294773274-4294959667
And no, you should not use any old capacitor - not unless you want a visit from the fire brigade and a claim on your household insurance. The X2 rating is there for a purpose, to ensure your safety and the safety of your property.
if you go by the manufactures PDF MOC3043 datasheet(4/6 Pages) MOTOROLA | 6-Pin DIP Zero-Cross Optoisolators Triac Driver Output or http://html.alldatasheet.com/html-pdf/53869/FAIRCHILD/MOC3043M/2467/6/MOC3043M.html the snubber and the type of load… – I built mine according the manufactures DOC and I have not had problems. but perhap I am wrong but my understanding is if it a resistive load a snubber is not really required- it only really required for inductive loads.
but since you’re just building s zero crossing SSR (moc304x) you could just buy a fotek ssr-40DA for $3 -5 and save yourself the trouble if you want random then fotek 40DAP(moc300x) for phase angle ( 40 is the amp rating D =DC controller type, A =AC switch P = pulse there is also V for variable it using pot control but like every thing from China buy double the size rating for long term hassle fee operation as 40 amp would be the maximum including the surge so working range is probably closer 25 amp then 40 in general )
Including a snubber as shown will reduce the conducted emissions, which arise because despite the claims, the triac doesn’t fire at the zero crossing exactly, but a fraction later - enough to generate unacceptable levels of RFI (in Europe at least - you might have more benign legislation).
The triac rating necessary (whether as a component or inside an assembly) is determined by its ability to always operate the circuit protection without damage.
Even a 16 A MCB will not protect the recommended BTA41 triac (rated at 40 A continuous) under all conditions (see Overload Protection of Mains Electrical Circuits — OpenEnergyMonitor 0.0.1 documentation)
That’s the precise reason to follow the manufacturer’s recommendations exactly, unless of course you are as expert as they are in their field.
If you search the old forum (“Archive”) there is a report of a fake SSR failing. Beware.
You know my father said exactly that. Since I will be dumping power on the 200W resistor, and at the maximum there will be about 180W, most likely I do not need that capacitor. Too bad I do not have oscilloscope to see what kind RFI that would or would not generate
thanks Robert, I will take a look at the wikipedia article.
The problem that I have (well shipping problem) is that to ship anything where I live cost many times more than the actual item 
I looked through the overload protection article, but basically I would say it is agreement to what I wrote. that about surges… if you require a 40 Triac for continuous use an 80amp to compensate for any surge. I know in Canada a 15 amp breaker generally pops on 25 - 30 amp surge due to time delay to compensate for start up surges and continuous it pop at 16 - 18 amps.
as to china “fake” well alot of case it just how they rate them. a lot of times they list surge as the maximum compare to using continuous that we use here . so if you buy a Chinese 15 amp breaker generally they operate at ~ 8- 10 amps continuously and pop at on surge of 15 amps