That's good advise, but in practice it is wishful thinking.
In 99% of board-to-wire connectors the male pin side is on the PCB and
the female socket side is on the cable.
Inside an enclosure that is not a problem. The PCB has many other
components anyway that carry exposed voltage, so the pin header adds
no danger. The cables are actually more important to shroud, since
they can come adrift and contact areas they are not supposed to
contact.
User accessible connectors are another story, but we are talking
inside the box here. Your project is low voltage anyway up to the SSR,
so there is no great danger.
As for polarization / keying the connectors. Again, nice if you can,
not the end of the world if you can't. There is no requirement if
these aren't user accessible. Just label them.
Personally, for something like a thermostat I would go with plug-in
PCB pcb screw terminals like this:
<
http://i.ebayimg.com/00/s/MTIwMFgxMjAw/z/zRsAAOSwHaBWlNS-/$_57.JPG>
There are good reasons why they are standard on temperature controllers.
ST
On Tue, Jun 28, 2016 at 11:48 PM, Brad Thompson
brad.thompson@... [Homebrew_PCBs]
<
Homebrew_PCBs@yahoogroups.com> wrote:
>
>
> On 6/28/2016 5:20 PM, alan00463@... [Homebrew_PCBs] wrote:
>>
>> I'm making my first PCB for a thermostat for
>> an electric heater. I need to connect the
>> electronics to several outside components:
>>
>> - a thermistor that goes in the oven
>> - an thermal fuse to shut off power if it gets too hot
>> - battery power & ground
>> - 3-conductor connector to an external solid-state relay
>>
>> I plan to use pin headers and matching sockets for each of
>> these four connections. For each of these four connections,
>> what criteria should I use to determine whether to put the
>> pin header on the PCB and the matching socket on the connect-
>> ing cable, or vice versa ?
>>
>> The thermostat itself and the SSR will fit into a plastic box that
>> also contains the battery. So my question pertains to orient-
>> ing the headers/sockets inside the plastic box. None of
>> the connections will ever be disconnected without first removing
>> four retaining screws from the lid of the plastic box.
>>
>>
> Hello, Alan--
>
> Standard procedure is to put sockets on any group of wires that carry
> hazardous voltages
> and thus could deliver a shock to an unwary person if the connector's
> pins were exposed.
>
> Also, when unplugged, exposed pins carrying voltage will inevitably
> short-circuit themselves on any
> nearby metal (that's one of Murphy's Laws)<g>.
>
> Also, if you're using identical connectors, if possible you should
> provide a means of keying
> or otherwise identifying which plug mates with which socket. If the
> connectors you're
> using don't have provisions for keying, label the plugs and sockets.
>
> HTH, and 73--
>
> Brad AA1IP
>
>
> ------------------------------------
> Posted by: Brad Thompson <brad.thompson@...>
> ------------------------------------
>
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