Connecting a space heater through an Arduino-controlled relay

Question

I'm considering connecting a space heater to a relay such as this: http://www.handsontec.com/dataspecs/2Ch-relay.pdf

The goal is to control it remotely using a GSM data connection.

The relay is only rated for 250V 10A. Will this still be 10A at 110V?

The space heater's maximum setting is 1500W = 14A (@110V). What would happen if I connected it at this setting? Would it simply put out 10A = 1100W?

Is there any danger to the relay by connecting devices that draw >10A? Is there any danger to a space heater or other device from not being able to draw enough current?

Answer 1

The image of the relays shows the rating is still 10A at 125V. The current rating of these relays is determined by the amount of heat generated by the contact resistance (plus the contact arm), limited by the thermal rating of the insulation that holds them in place, so there's no additional current gained by operating at lower voltages.

From experience, these cube relays don't last that long when running close to their ratings - though a few thousand cycles may be still acceptable for a limited application that was within the limits.

What you must avoid though is failure by contact welding, and this can occur if you are allowing currents above the rating. Low inductance loads, like heater coils, where the current is established rapidly on contact close, and may be interrupted by bounce, is the worst case for this.

The relay will provide no limit on the current the load draws, so you will get the full 14A. This would certainly damage the contacts, possibly causing welding so do not use this module. Go find a higher rated relay.