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Support Center / Plumbing & Electrical / Which Cord Plugs Where: Identifying Control Boxes, Cords, and Air Tubes After Installation

Which Cord Plugs Where: Identifying Control Boxes, Cords, and Air Tubes After Installation

Updated September 2026

Which cord plugs where on an Ella walk-in tub is answered by the component diagram for your therapy package: every pump, heater and control box is labeled at the factory, each power cord goes to its own dedicated GFCI outlet inside the equipment compartment, and the thin air tubes run from the deck push buttons to the nipples on the control box. Behind the front apron you will find one or more control boxes, a handful of power cords, those air tubes and ground wires. This article explains what each box does, which cord and tube connects where, and how the 20 amp plug and the grounding work, so you can confirm your installer's connections or reconnect things after a service call.

Start with Your Package Diagram

Every therapy package has a published component diagram showing the pumps, boxes and outlets. The full set is linked from the comparison page at ellasbubbles.com/walk-in-tub/comparison/ and from each product page's Downloads tab, and the electrical requirements are on the technical specifications page. The number of dedicated 20A/120V GFCI lines depends on the package: one line for hydro only or a single-seat air plus hydro package, two lines when a second hydro pump, microbubbles or the heated seat is added, and three lines for the ShaK and Big4One digital package with microbubbles and for the two-seat full package. See the electrical requirements by model for the full table.

The Master Control Box

Tubs with a heated seat and multiple massage systems use a master control box, which runs the massage systems and the heated seat together. In the video the connectors are identified one by one: a port for the heater pads, a port for the air pump, a port for the water pump, and the main power inlet. Along the side are the air-tube nipples for the deck push buttons: the hydro pump push switch, the air blower push switch and the LED light push switch. There is also a display port for the digital control keypad, which does the same things as the push buttons in digital form, a connector for the LED chromatherapy light, and a config switch used to program the box. A green light shows when power is flowing into the box.

On triple-massage tubs such as an Ultimate with three pumps, the control box runs two pumps, the air pump and one water pump, while the third pump is powered separately along with the in-line heater, which is why two dedicated lines are needed. If one massage system does not work, check that its pump is plugged in and powered before anything else, and confirm the green power light on the box. The pump not working article walks through that check in order.

Blue Ella walk-in tub master bath controller with labeled pump air switches, blower, ICL light port and power LED
A master bath controller: air-switch nipples, blower and pump ports, the ICL light connector and the green power LED are all labeled on the case.

The 20 Amp Plug

Some master control boxes have a standard three-prong 15 amp connector, while others have a true 20 amp plug that you can recognize by its blades: one vertical and one horizontal. That plug needs a 20 amp receptacle, which any home center or electrical supply store carries. Ask your electrician for a 20 amp GFCI-protected receptacle on the dedicated line. Never use an extension cord to power any tub component. If a cord will not reach, the fix is to place the outlets where the pump and heater cords reach them, preferably under the seat area inside the tub compartment, not to extend the cords. Planning those outlet positions is part of planning service access.

The Gray Chromatherapy Box and the Blue Air-Only Box

The video walks through the two smaller boxes. The chromatherapy control box turns the LED light on and off and cycles its colors. It is powered through the three-prong connector on the back, the LED light connects to the three pins, and the push-button air switch tube connects to the nipple. The air massage control box works the same way: three-prong power, the air pump on the three-pin connector, and the air switch tube on the nipple. As shown in the video, that box gives you three speeds, high, medium and low, plus a fourth wave mode that ramps the pump up and down, and then off. It also runs the Auto Purge, which starts automatically about 20 minutes after you turn the air massage pump off, runs for 120 seconds and cannot be interrupted. If the blue box shows no power light, or the air pump runs constantly, see blue control box has no power light.

Two-seat tubs add a separate heated seat box and keypad for each seat, and each side has its own foot pump and intensity dial, so a problem on one side is diagnosed on that side's box and pump.

Push-Button Air Tubes

Ella push controls are pneumatic. Pressing the button sends air pressure through a thin red tube to a relay inside the control box, and you should hear an audible click inside the box when the relay activates. Make sure the red tube is pushed firmly onto the nipple at the box, with a twist-and-push motion, and secured at the push button with the locking nut. On the Standard and Zen platform, the push-control air pipe connections must be verified tight before the installation is finalized. If a button is stuck down, disconnect the red tube at the box to relieve the air lock, let the button pop up, and reconnect. When nothing responds after checking the tubes, the control box reset guide is the next step.

Grounding the Frame

It is vitally important to ground the tub correctly. Ella tubs come with ground wires on all electrical components and on the tub frame, and your installer secures a proper ground connection in accordance with all local and state electrical codes. The warranty activation checklist includes an installer initial for a grounded frame.

Electrical Requirements Refresher

As the video states, all electrical components are clearly marked and easily accessible. Your contractor must use dedicated GFCI-protected outlets, the tub cannot share a circuit with any other appliance, and the amperage must match the number and type of components in your tub. If a breaker or GFCI trips after everything is connected, breaker or GFCI keeps tripping explains how to isolate the cause.

Common Questions

There are several plugs and no diagram. What goes where?
Pull the component diagram for your therapy package from the comparison page or from the Downloads tab on your product page, then match the labels on each box to the diagram. Plug each pump and heater into its labeled port on the control box and into its own dedicated GFCI outlet, and push each air tube onto the nipple that matches its deck button. Electrical diagrams are not packed in the crate, but the cords themselves carry factory labels such as Line 1 and Line 2 to guide the connections.
What is the 20 amp plug with a sideways blade?
A plug with one vertical blade and one horizontal blade is a true 20 amp plug. It requires a 20 amp GFCI-protected receptacle on a dedicated line, which any home center or electrical supply store carries. Ask your electrician to install the 20 amp receptacle rather than adapting the plug.
What plugs into the gray and blue boxes?
The gray chromatherapy box takes power through the three-prong connector on the back, the LED light on the three pins, and the LED push-button air tube on the nipple. The blue air-only box works the same way: three-prong power, the air pump on the three-pin connector, and the air push-button tube on the nipple. Make sure each tube is pushed firmly onto its nipple with a twist-and-push motion so the button's air pressure reaches the relay inside the box.
The big black cord will not fit the GFCI outlet and only the microbubble plug works.
The larger plug is the 20 amp plug for the master control box or hydro pump, recognizable by its one vertical and one horizontal blade, and it needs its own 20 amp GFCI receptacle on a dedicated line. The smaller plug fits because it is a standard three-prong connector, while the 20 amp plug will only fit a 20 amp receptacle. Ask your electrician to add the 20 amp receptacle rather than adapting the plug, and never use an extension cord.
The cord is too short to reach the outlet. Can I use an extension cord?
No. Extension cords are never used on any tub component. If a cord will not reach, the fix is to have the electrician place the dedicated GFCI outlets inside the equipment compartment where the pump and heater cords reach them, ideally under the seat area, rather than extending the cords.
How is the frame grounded?
Ella tubs come with ground wires factory-fitted to every electrical component and to the tub frame. Your electrician secures the ground connection in accordance with all local and state electrical codes, and initials the grounded-frame item on the warranty activation checklist. Grounding the tub correctly is vitally important, so please do not skip this step.
Are the Temp Sens and Water Detect ports supposed to be empty?
Some control boxes carry labeled ports that are not used on every configuration, so an empty port is not necessarily a problem. Please do not improvise a connection to fill it. Send a photo of the box label, the empty ports, and your serial number to the team through a support ticket, and they will confirm exactly what your unit requires.
What does the config switch on the master control box do?
The config switch programs the master control box for the therapies connected to it. The control box reset guide shows when to press it as part of a reset. Otherwise, please leave it alone unless the team asks you to use it during troubleshooting.
One massage works and the other does nothing. Where do I start?
Check that the silent system's pump is plugged in and its outlet is live, and confirm the green power light on the control box. Then check that the push button's air tube is firmly on the control box nipple, using a twist-and-push motion, and listen for the audible relay click when you press the button. Most one-system failures are a missing air connection or an unplugged pump, and the pump not working article walks through the check in order.

Have a question that depends on your exact model or configuration? Open a ticket at ellasbubbles.com/support or call (800) 480-6850 and our technical support team will be glad to help you and your installer.

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