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Control Panel (Part 2)

 

STEP 1: Supply power

We need to supply power to our control panel to run the various lights and switches and also allow it to run the pumps and heating elements.

The heating elements are power hungry so more power than what a standard 120V AC 15 amp outlet can provide is required. We need to supply twice the voltage (240V AC) and almost twice the current (30 amps) in order to run all of the devices connected to our control panel.

To provide this extra power we use a standard 4-slot North American clothes dryer outlet as it is capable of providing both 120V and 240V AC at up to 30 amps.

With everything running (including both pumps and one heating element) our current consumption is almost exactly 24 amps. A standard 4-slot North American clothes dryer outlet is therefore perfectly sized in terms of current capacity to run our control panel.

We purposely designed our system to use no more than 30 amps as dryer outlets are easily installed and/or are already available in most homes. It also makes our setup somewhat portable if we wish to bring our equipment with us and brew elsewhere.

Standard 120V AC 15 amp outlet (left) and 240V AC 30 amp dryer outlet (right):

 

Residential power

In North America, most residential power comes in to the house as 240 Volts AC over 3 wires: Two HOT wires called 'A' and 'B', and a NEUTRAL wire. This power is fed in to your circuit breaker panel which splits it up and feeds it into different circuits throughout the house. The breakers are used to protect the wires in these circuits from overheating. Breakers do not protect the equipment or the people using the equipment.

By connecting (called 'tapping') across different pairs of the three wires we get different voltages:

  • 120V AC: By tapping across either of the HOT lines and NEUTRAL for standard household devices such as lights, televisions, computers, etc. Single-pole breakers are used and take up one slot in your breaker panel. Approximately half of the circuit breakers in a house will use HOT 'A', with the other half HOT 'B' in order to try and balance how power is consumed.
  • 240V AC: By tapping across the two HOT lines for power hungry devices such as electric stoves, clothes dryers, air conditioning units, baseboard heaters, etc. Double-pole breakers are used and take up two slots in your breaker panel. 

Single-pole breaker (left) and Double-pole breaker (right):

We use both voltages in our control panel: 240V AC for our heating elements and 120V AC for all of the other devices (pumps, lights, PID controllers, etc.)

There is a 4th wire too: Somewhere near the house is a rod buried in the ground with a wire attached to it that is connected to the circuit breaker panel. This is the 4th wire used in residential electrical systems and our control panel. It's called the GROUND.

In our brewing setup a ground is used for safety: The GROUND line is electrically connected to the kettles and the control panel enclosure in the same way a power tool or appliance chassis is grounded. In the off chance that something goes wrong and one of the HOT lines becomes disconnected and touches the control panel enclosure or one of the kettles, the GROUND line ensures that any stray current can find its way to ground through a wire instead of through something else (such as the brewer!). Without proper grounding the enclosure or kettle would simply become energized and pose a great danger to you, the brewer. An electric brewing setup should always have everything properly grounded. With proper grounding the current will instead immediately start to flow and trip the circuit breaker, turning off power.

Our standard North American dryer outlet provides all 4 wires that we need (two HOTs, one NEUTRAL, and a GROUND). As mentioned previously, we get 120V AC by tapping across either HOT line and NEUTRAL, and 240V AC by tapping across both HOT lines.

Note that some clothes dryer outlets may be rated for 240V AC / 30 amp use but only have 3 wires (not 4). We do not recommend using these outlets as they are no longer up to code as they have tied (bonded) NEUTRAL and GROUND together. For safety reasons, in most locations today, NEUTRAL and GROUND may only be bonded at the circuit breaker panel.

The standard 4-slot dryer outlet we installed to supply both 120V and 240V AC with ground to our control panel.

 

Ground Fault Interrupter (GFI)

A GFI is not to be confused with a circuit breaker found in your electrical breaker panel. Regular breakers are rated for specific current ratings and will switch off (or 'trip') if ever the rated current is exceeded on the circuit they control. The sole purpose of breakers is to protect the wires from overheating. 

A GFI (or more accurately, a residual-current device) on the other hand is not used to protect wires or devices - it protects the equipment operator. A GFI will cut power when it detects that the current going in to a circuit does not match the current coming out of the circuit. Often this imbalance (typically only a few milliamps) is caused by current leakage through the body of a person who is grounded and is accidentally touching an energized part of the circuit.

The distinction is important: A circuit breaker saves equipment, a GFI saves lives. GFIs are designed to prevent electrocution by detecting the leakage current, which can be far smaller (typically 5–30 milliamperes) than the currents needed to operate conventional circuit breakers or fuses (several amperes). GFIs are intended to operate within 25-40 milliseconds, before electric shock can drive the heart into ventricular fibrillation, the most common cause of death through electric shock.

While the electrical code varies from country to country, in the United States GFIs are typically required in kitchens, bathrooms, and other places that can be wet and the National Electrical Code (NEC) requires that GFI devices intended to protect people interrupt the circuit if the leakage current exceeds a range of 4–6 mA of current (the trip setting is typically 5 mA) within 25 ms. In other places the trip setting may be as high as 10-30mA.

A GFI should most definitely be used in the circuit that powers your brewery control panel. This GFI can be installed in one of two places: Either in the double-pole 30 amp circuit breaker in the electrical panel, or in-line with the control panel power cord. We recommend that you check that whatever GFI you intend on using adheres to your local electrical code in terms of trip settings and speed of operation.

Very popular amongst electric brewers are 240V AC 30 amp GFI cords that were previously used to power Xerox copy machines as they can sometimes be found on on eBay for less than a double-pole 30 amp GFI breaker. It's important to note however the 30A GFI cords have a trip setting of 10mA (slightly above the United States NEC requirements).

240V AC 30 amp cord with GFI built in:

Approximately half a dozen different electrical panel brands exist (Cutler Hammer, Seimens, GE, etc.) so if you purchase a double-pole 30A GFI breaker make sure that it matches your electrical panel. Refer to a qualified electrician for assistance if required.

Please do not forgo using a GFI thinking that simply being 'careful' will be enough. Like the seat belts in your car, a GFI exists because accidents or failures happen, even on properly designed, built, and operated equipment.

 

Install dryer outlet 

DISCLAIMER: Always follow electrical code requirements specific to your area, and before undertaking any home electrical project, contact your local electrical authority and your insurance company to ensure that you comply with all policies, warranties, regulations and authorities concerning this work.
 

If you don't already have a standard 4-slot 240V AC 30A dryer outlet handy to power your brewery, you're going to have to install one.

Detailed instructions for installing this outlet and corresponding double-pole 30A breaker or double-pole 30A GFI breaker are not provided on this website. All breaker panels are slightly different and national/regional electrical code may also be slightly different based on exactly where you live.

We recommend that you refer to a qualified electrician if you have any questions on how to safely install a dryer outlet as an electrical breaker panel can be a very dangerous place.

We will, however, provide you with the general steps:

  1. Cut the electrical breaker panel main power.  
  2. Install a double-pole 30A breaker (with GFI if your power cord does not include one) in the panel. The breaker must be matched to your panel brand/type as breakers are panel-specific.
  3. Following electrical code for your area, install a dryer outlet in a conduit box.
  4. Following electrical code for your area, install 10-3 wire (10 gauge wire, three conductors, with ground) between the new double-pole breaker and the dryer outlet.
    In the breaker panel the two HOT wires (red and black) are connected to the two breaker HOT poles. If installing a GFI breaker the NEUTRAL wire (white) from the outlet is connected to the breaker NEUTRAL pole and the white pigtail wire from the breaker is connected to the neutral bus bar in the breaker panel. If installing a non-GFI breaker the NEUTRAL wire (white) from the outlet is connected directly to the neutral bus bar in the breaker panel. In all cases the GROUND wire (green or bare) is connected to the ground bus bar in the breaker panel.
    In the dryer outlet the two hot wires (red and black) are connected to the straight slots (often labelled 'X' and 'Y') with brass screws, the NEUTRAL wire (white) is connected to the L-shaped slot with the silver screw, and the GROUND wire (green or bare) is connected to the D-shaped slot with the green screw. 
  5. Re-enable the electrical breaker panel main power and turn on the new double-pole 30A breaker.
  6. Use a voltmeter to measure the voltage between various points on your new dryer outlet. You should see 120V AC across either HOT and NEUTRAL, 120V across either HOT and GROUND, and 240V AC across HOT A and HOT B. If using a GFI breaker, press the test button to trip the breaker and re-measure: The 120V AC and 240V AC readings should now be 0V.

  4-slot dryer outlet wiring: