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Relay board shield for Raspberry PI

Former Member

Hello,

 

We have been breaking our heads to find a Relay board shield that just plugs into the Raspberry PI, since many of them require that you also buy an Arduino

to plug into the board.

 

To save you some further search,  here is the Shield:

 

http://www.robogaia.com/4-relays-raspberry-pi-plateshield.html

  • WARNING !!!

     

    To anyone buying this relay board - although the relays are rated for 250V AC it will not be safe to connect to the the UK AC mains.

     

    This is important - if you connect this board to the mains you risk serious injury or death.

     

    MK

  • in reply to michaelkellett

    I'm with Michael on this.

     

    While it appears that the layout has a large earth plane between the high voltage and low voltage sides, there is no connection for an earth. (from the available pictures)

    Given the close proximity of the underlying components, I would strongly suggest that anyone contemplating mains voltages fit a piece of insulating film on the underside of the board to ensure accidental contact is NOT made by fingers/parts or anything else.

     

    For the designers

    1. You should add a decent earth connection point, (OR stop advertising the mains rating of the relays.)

    2. Consider fitting the connectors together to give better physical strength (since they should be 230v rated).

     

    Mark

  • in reply to michaelkellett

    Michael Kellett wrote:

     

    To anyone buying this relay board - although the relays are rated for 250V AC it will not be safe to connect to the the UK AC mains.

    Michael, since anyone with even a bit of experience will have taken one look at the photos and made their own mind up, I can only assume you're aiming that comment at the people with little or no EE knowledge/experience.

     

    As such you should really try to explain why you believe it's not safe. Not doing so makes your statement a lot less credible.

  • in reply to Former Member

    @ Selsinork - I see postings advising and/or encouraging dangerous electrical connections all too often. I don't have the time or the capability to teach every one who might see them how to connect safely to the UK mains. I could stand back and say nothing but I think I should at least make some comment when I see the most hair raising examples - there is at least a chance that some one will be alerted to the danger and saved from a potentially serious accident.

     

    It really does matter:

     

    (from  http://www.esc.org.uk/industry/policies-and-research/statistics/)

     

    Deaths, Injuries and Fires

    1. Low voltage electrocutions and fatal electrical burns in GB from low voltage electricity supplies (2010 data) i

    • Total:      28
    • Work      related electrocutions: six
    • Home      or leisure electrocutions: 22

    ·         Northern Ireland – Average of 1 electrical fatality per year ii

    2. Electric shocks iii:

    • People      receiving a mains voltage electric shock per year (15+): 2.5 million*
    • Of      whom received a serious injury: 350,000**

    The figures above relate to the UK 2010.

     

    MK

  • in reply to michaelkellett

    Michael

    I always knew you lot were 'shocking' but those are high figures alright.

     

    I won't give advise on connecting to the Mains for the simple fact I cannot see the work before it is connected, and we all now that a little information in the wrong hands is dangerous.

     

    Your warning people is perfectly valid, but I think Selsinork was suggesting a brief qualifier about why would help.

    Its certainly not suitable for NZ or Australia, and probably any othe 230v mains country as well.

     

     

    For an article in the magazine I pondered for a long time about how to safely switch the Mains, and then came across these.

    http://www.wattsclever.com/products/easy-off-sockets

     

    Together with RCSwitch https://code.google.com/p/rc-switch/ and a 433MHz tx, (How to http://code.google.com/p/rc-switch/wiki/HowTo_Send ) you can control more than the 3 that the remote does.

    If you remove most of the non required in the library it even works well in a Digispark http://digistump.com/category/1

     

    Cheers

    Mark

  • in reply to mcb1

    I'm all for people (including me when possible) using ready made RC sockets for mains control - not always suitable of course, but  a really safe way of getting isolation.

     

    MK