PreSale Questions (Spark Core + Relay Shield)

Hello all ,

I just noticed the spark kick-starter campaign. And i am very much interested in the Spark Core.

I have few questions before i go ahead and order few Spark Cores.

  1. Can i use Spark Core without Internet, Just as a wifi client to talk to other wifi clients/server in my home network ? Or It needs to be connected to Internet all the time ?

  2. Can i use the Spark Core Relay Shield which is 120V to control appliances which are 240V ?
    I would like to control a motor of 240V , 5AMPs and
    Motor of 240V, 20 AMP.


  1. the answer is yes. Not directly but yes that feature is possible.

  2. I think the relay shield can handle 240v as well. Maybe just not so high a load current. Let me pull up the datasheet and get back to you

Something like 6A would be the max.

SPECIFICATIONS Operating voltage: 7 to 15V DC Current consumption: 150mA min to 290mA (at 9V DC) Relay Max Voltage: 250V AC Relay Max Current: 10Amp at 125V AC Relay Part Number: JS1-5V-F (Data Sheet) Dimensions: 3.5 x 3.3 Weight: 100gms

20A is definitely over the limits. Standard outlet is only 13A and your motor for that rating sounds industrial…

Thanks for your reply.

  1. If its possible ,then how ? (you said “Not directly”)

  2. Motor is actually Bore-well pump, on the Pump controller the Amp meter shows around 12-15 AMP while in use but the Meter has 30 AMP max reading, so on the safe side i am looking for something that can handle 20 AMPs.

Ill confirm the AMP usage with someone more technical.

Thanks for your time.

There’s a discussion just starting now about whether user code should be able to run at bootup even without internet.

So the issue for now would be, you need to 1st connect to internet before the code starts running. If you get disconnected after, it’s fine. The code still run.

But if you don’t mind compiling and coding locally, there’s no issue on this. You can use some code to change the behavior. Details here:

The relays will not support this amperage, they are rated at 125Vx10A. The application you considering, 240v x 20A requires industrial type switching / relays and all the safety statements around mains voltage apply BIG time. You need to be very aware of what you are doing and if unsure, which is inferred by the post you need to proceed with great caution. In many counties you would need multi-phase mains power, commonly referred to 2 phase or 3 phase power for this type of application.

Industrial type relays capable of this type of load are readily available and and you can use the spark relay shield to drive the industrial relay. Depending on your choice of relay this ensures the spark-relay is only exposed to comparatively low voltages and low amperage and therefore isolates the spark circuity from the required industrial loads. Installed correctly this then protects the spark as well as people servicing the spark.

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Hi @zingabuka

How is the bore-well pump motor controlled today? If it has a relay controlling it already, you should use that.

You need a large relay to control a motor at 12-15 running Amps. The start-up current for the motor (called locked-rotor amps or LRA) is going to be much larger than the running current and a multimeter may not capture the high-current spike right as you turn on the motor. This current is typically three to six times the nameplate rated current, so if the motor is rated 15A you should be thinking the LRA can be 90A.

If the motor has a horsepower rating and you should look for a relay rated for that horsepower. The failure mode is often that the relay contacts weld themselves together and the motor will not turn off. As @deancs says, there are a bunch of safety issues to think about.

You can use the relay shield to control the larger relay, for sure!


Thanks , looking in to it.

i can compile and code locally, the reason i want it to work offline, is i am in remote area, so many times there is no electricity and many times there is no internet too.
this is why i am looking something completely offline.


Thanks for your input.

The pump-motor is using Single-phase connection, its for home use.
I get your point, control the high load relay using the spark-relay shield. but have to be extra careful as something goes wrong, is there chance of messing up the 400 feet underground motor ?

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Thanks for your reply.

bore-well pump motor controlled today by using the Controller provided by the Motor Manufacturer.
I have created album of few pics.

When i Hold the start button for few AMP needed goes to the all the way to the 30 AMP point, is that a LRA ?

The pump is 400 feet underground so cant check the horsepower rating

The Relay inside the Controller reads

P30FC-10-12V DC
DC 12V-120 OHMS

I guess i cant use that one, i have to buy new one of the exact same specification and use it to start the pump.

Thanks for your time.

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Thanks for the pictures–that really helps!

So you have a 12V DC coil relay with 30A 250V contacts–a very standard part. If you are replacing this entire box, you can get a new relay, but you could also re-use this one.

Motors have starting capacitors which in your case looks like they are in that box. A lot of motors have centrifugal switches that turn off the starting caps when the motor is up to speed, but this motor might not have that. I see heavy wire going to the starter switch which makes me think the motor does not have the centrifugal switch.

Do you have to hold the green start button for a second or two to start the pump normally? If so, you will need a starting relay and a running relay to duplicate that way of working.

You are going to need all those starting capacitors that are in there now. It is unusual to have so many and to have some added in the bottom of the box like that.

The red stop button looks like it is only low current or low voltage and probably interrupts the voltage to the coil of the LEONE 30A running relay.

The 30A analog meter is not telling you the actual starting LRA. You need more sophisticated test equipment to get the real number, but if you have a 30A relay in service now, you need at least that big a relay in the future. Relays are a mechanical part that wear out and need to be replaced periodically, so they are always available.

That is actually quite a big project and very nice to see!


Yes you can run the core offline, we’re working to make that easier since the default behavior is to try and be online, but it’s definitely possible.



Thanks , thats a lot new info for me.

I am planning to use the Box as it is because there is another circuite inside the box which handles the
**Overload cute-off
Dry Run cut-off

I’ll just take wires from the Green Button which is NCNO button (just learned) and replicate the Button’s scenario using spark-core.

And yes , while powering on the Motor i have to press and hold the Green Button for at least 5 Seconds (Confirmed with mechanic , as its is necessary to jump start the motor).

About the NCNO button, i guess i have to study how that works to replicate the scenario.


Thats very great, i am looking forward to use spark-core completely offline.

You can use a SSR to replace the button but a Mechincal relay would be better for that kind of load :slight_smile:

Problem solved :slight_smile:

Hi @zingabuka

I think you are smart to use the existing controller! If I am reading the photo right, you will need at least two relays controlled by the Spark core, one for the green switch to start and one for the red switch to stop.

It looks like the green start switch carries motor current and energizes the relay, so if that’s right you might still need one high-current relay for the starter current. If I am right, the green switch has both NO start switch contacts and separate NC running contacts to hold the running relay in to top of box in.

You will need to wire a NC relay in series with the red stop switch to open the circuit holding the relay in while running.

Like I said, this is a big project! Please be careful–that voltage can kill.


i guess i’ll go with mechanical relay.




I am checking the button first , to find out how it works. i mean which contacts getcs connected.

Sure, i will be careful.

I guess it will take some time, ill bump this thread , when i am good to go.

Thanks for your time .


Is there newsletter of something which will notify me, one its done ?


You will hear from the official update/sprint if that is the included improvement.

Otherwise, you can monitor the github issue. I mentioned it to @zachary last night again on this issue.

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Thanks , will keep an eye on the github issue.

one more thing i would like to know, sorry for being noob.
Can i buy spark-core now and is there feature to update the sparkcore firmware later ? when this issue is resolved ?

or should i wait and buy the spark-core later when the issue is resolved ?


Hi @zingabuka,

We also post new features and details about our sprints on the blog ( ), and here on the community, and you can always follow the firmware repo on github here:

Firmware updates are progressively rolled out to cores when you flash new firmware, so no need to wait. :slight_smile:



Thanks for the info, will keep an eye on the blog.
Its awesome feature that i could flash my core with newer firmwares.

Good question! I answered it recently so have a read :slight_smile: