240VAC Mains Wire to Board connector

[veryevil]

Hey, I need to make up a cable assembly which has 5 wires that go to a plug which plugs into a connector only one way round and a complete Muppet could connect up.

The cable will have the following:

240VAC Live
240VAC Neutral
240VAC Live Switched
240VAC Neutral Switched
MAINS EARTH

The wires carry very little current (well under an amp) so that isn't the issue.

I've been told that I cannot use a screw terminal header or Spade connectors as Muppets might connected the individual wires the wrong way round so it has to be a single connector that is just plug and play.

What connectors would you recommend and what is a sensible pin pitch to use for a connector with mains pins together?

Thanks Steven

[ColinB]

I've seen power supplies use Molex KK-156 connectors for 120Vac, I think they left a missing pin between hot and neutral however, and that's not 240v...

[SeanB]

Bulgin make a nice range of mains rated multipole connectors. Look at industrial multipole connectors with crimp connections.

[Bloch]

I like Phoenix Contact


They have many different connectors. But maybe MSTB 2,5


http://eshop.phoenixcontact.dk/phoenix/treeViewClick.do;jsessionid=QG1Zp2GLS9Yyx2SWTn6ckXjBd2GsvLPSdKrZjBlNYhGLSj1gdNYv!529380903?UID=852630759&parentUID=&reloadFrame=true

[ciccio]

You need at least a 7.92 mm  (30 mils) pin pitch for 240 V on a PCB connector.
The cables cannot be too thin, at least 0.5 or 0.7 mm2, so the crimped contacts cannot be too small.
Some regulation may apply to the PE cable size.
I use JST VA series connectors    http://www.jst-mfg.com/product/detail_e.php?series=259    (they have only 2 pins) but you can use anything similar , taking care to remove alternate pins (they can supply the connectors without the un-needed pins).
Molex too has something similar.
Best regards

 

[Bloch]

You need at least a 7.92 mm  (30 mils) pin pitch for 240 V on a PCB connector.

Why so long pin pitch ?


http://www.goldphoenixpcb.com/html/Support_Resource/prdt/arc_125.html and http://www.smps.us/pcbtracespacing.html

Experiments performed by UL in the course of analysis of silver PCB surface finish, demonstrated that the withstand voltage of a pair of parallel conductors is purely a function of conductor spacing, not surface finish. Based on the experiments, UL specified withstand voltage of 40 volts/mil or about 1.6 kW/mm in their test methods of UL796 Standard for Printed Wiring Boards. In my view, it is reasonable therefore to use these numbers in designing the board to withstand a particular HiPot. For example, for working voltage 500V you need to meet the withstanding test voltage 1740 Vrms per UL 60950-1 Table 5B. Such AC signal has 1740*?2=2461 V peak value. With the 40V/mils criterion, the required minimum spacing would be 2461/40=62 mils (or 1.6 mm).

62 mils (or 1.6 mm)

[ciccio]

Why so long pin pitch ?

In fact, you are correct, because referring to UL 60065, figure 10,  for 230 V mains (230 + 10% = 253 V x 1.41 = 357 V peak) the minimum clearance or creepage distance  between conductors on PCBs results about 1.1 mm.
If you consider a pin diameter of 1.7 mm, a suitable  pad size can be 2.5 mm (if an oval or rectangular pad is used, this can be the smaller dimension), so with a 3.96 mm pitch connector you get a 3.96 - 2.5 = 1.4 mm creepage distance, very close to the limit.
A 5.08 or 5.0 mm pitch connector could be used, but most people prefer to use the lower cost 3.96 mm pitch without a pin, resulting in 7.92 mm pitch.
Please look inside any consumer electronic product: you'll see JST VA connectors everywhere, expecially on single sided boards, where mechanical strength requires larger pads.
Best regards

[veryevil]

Hey, thanks for the info. The JST VA series isn't availiable from Farnell, RS, Digi-Key or Mouser which is annoying and it also is only 2 pins.

I did find these connectors on Farnell http://uk.farnell.com/jsp/level5/module.jsp?moduleId=en/353567.xml which have a 6.35mm pitch. I could use a 3 pin and a 2 pin header and separate the switched mains signal.

I guess I could use these with a 4.2mm track and 2.15mm clearance, Yes / No?

Any other suggestions welcome!

[ciccio]

I did find these connectors on Farnell http://uk.farnell.com/jsp/level5/module.jsp?moduleId=en/353567.xml which have a 6.35mm pitch. I could use a 3 pin and a 2 pin header and separate the switched mains signal.

I guess I could use these with a 4.2mm track and 2.15mm clearance, Yes / No?

Yes, you can be sure that any safety regulation is respected.

Speaking of creepage distances, I have a story for you:
The assembler finished his stock of standard solder wire, and being Saturday and an a schedule, he bought some "no name" wire from the local hardware store.
He soldered about 100 relays on the boards of the  temperature controllers we were manufacturing, and the units were tested and put in the burn-in room, with mains connected to the relays.
After about 12 hours a terrible smell was felt in the lab:  the flux in the "hardware" solder was conductive, and mains a.c. was passing between the pins of the relays, and the there was enough heat dissipated to burn the fiberglass of the PCB.
Small creepage distances need a very clean board..

Best regards