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Connect Mats

How to properly connect more than 1 mat

PEX Universe Docs

Q: Can I connect more than one mat? If so, how?

A: More than one mat can be connected quite easily but there are few important rules to follow:

1. PARALLEL CONNECTION ONLY just like shown below for two mats (4 connecting wires) and Elektra UCCG programmable thermostat:
Power + Ground from the box

4 cold wires


PARALLEL CONNECTION for 2 Elektra MG mats and Elektra-Microline MTC2991 thermostat with floor temperature sensor:


2. Observe the maximum Amperage draw of the mats. Both thermostats are limited to 16 Amps! Check or ask an electrician to check the allowable load on the particular circuit
If the circut allows for more Amperes than the thermostat then the contactor is needed.

Contactors come in many shapes and forms.


Contactor is like a switch in the OFF position. When appropriate voltage is applied to the contactor's coil terminals, 'the switch turns itself ON'.
In his case the coil voltage is applied by the thermostat calling for the heat.

Contactor is meant to take the load of the control device - a thermostat in this case. Please note how the contacts of the thermostat (where normally the floor heating would be hooked up), are connected to the coil of the contactor and the contactor is handling the connection between the power source (GRAY wire) and the load of the floor heating mats (4 white cords) in this case.





Two parameters of the definite purpose contactors are important:
  • Max. Amperage.
  • Coil Voltage.
    If the thermostat voltage is 120V then the contactor's coil voltage HAS TO BE 120V, but the mat(s) can be 240V BUT CONNECTED BY WAY OF A CONTACTOR TO 240V power source. The same can be said about 120V when connected to 120V power - but again - by way of the contactor.
  • Contactor's coil voltage has to agree with the device 'driving it', the thermostat in this case.
  • Mats (or tubings) voltage has to agree with the voltage of the power source regardless of the contactor's coil voltage. Mat's (or tubings) TOTAL AMPERAGE has to be smaller than the one of the contactor AND THE AMPERAGE OF THE POWER SUPPLY.
Please Note: nothing should be subjected to operation under full load for long periods of time even if allowable by specs.

This said, if the thermostat max. load is 16A, and if the real load from floor heating is 14A or more: USE THE CONTACTOR! Definite purpose contactors are inexpensive and not difficult to connect.

2 phase definite purpose contactor in the dual gang electrical box.


Below:
4 large 1200Watts/240V mats connected to the bottom side of the definite purpose contactor. 2 wires (black and white) from the load side of the thermostat connected to the left and right side of the contactors coil. Please note: 1. All the ground wires (YELLOW/GREEN) connected together
2. All the mat's BLUE wires connected to one phase of the contactor and all the mat's BLACK wires connected to the second phase of the contactor. Yellow power wire not connected yet. Before connecting, each 133 sq.ft. (12mē) 240V, 1200Watts mat resistance was 43 Ohms. When connected in parallel like shown above the resistance of this set is 10.9 Ohms. Based on the Ohm's law: 240V/10.9? = 22 Amps.
The limit for the resistive load of this particular contactor is 30Amps Please remember: Electricity can be deadly and wiring done incorrectly can kill and start deadly and destructive fires even when "just replacing one small receptacle."

YOU ARE DEALING WITH LINE VOLTAGE, not low voltage!

NEVER EVER attempt to work or even touch the inside of the electrical components without being 100% sure that the power is disconnected!

If you are not an electrician and if you have the slightest doubt about your wiring ability, please contact a licensed electrician and/or repairman before doing any diagnosis, repairs or installations. The products shown here are deemed SAFE and sound by various testing authorities but the wiring process can only be SAFE when done with safety precautions. Please read manuals and/or ask pros when not sure. Most of the simple installations shown here can be done by yourself or you can have someone qualified do it for you and THEN have the electrician check it and connect it to power.

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