Your thoughts on this bond

I mostly do not see a bond on a “plug-in” whirlpool tub motor.

This one had a bond to the tub valve with CPVC piping.

GFCI protected circuit.

What are your thoughts on this install?

Consider where the stray power is going to go if the motor fails.

Is some code applicable here?

Too funny David. LOL

Technically proper for the theory behind “bonding.”

The main purpose of “bonding” is not to direct stray voltage (that is the purpose of “grounding”), but rather, bonding is intended to eliminate the potential for transfer of current between components. A proper bond will also include a solid grounding connection that will produce a fault large enough that it will open/trip the OCPD of the circuit, in the event that there is “stray” voltage.

Think about it this way (I know you understand this David, but many are still confused about the principles of bonding);

When you rub your feet on the carpet and touch a door knob, you get a static shock. That is the transfer of current, which bonding will prevent. If you are holding the door knob (“bonded” to the door knob) and you rub your feet, you will not get that shock if you touch the door knob with the other hand.

That’s because you and the door knob share the same electrical potential (potential to ground). The static build-up is the same within your body as it is with the door knob while you are “bonded” to it.

Now if someone else comes along and touches you or the door knob, they will receive the charge (shock) that is being stored from when you were rubbing your feet on the carpet (i.e. “stray” voltage). That’s why the grounding connection is important.

The grounding connection will take that charge to “earth.” In the case of an electrical circuit, it will open/trip the breaker.

Care to elaborate on why this is “Too Funny”, or is it “a CMI thang”??? :shock::roll:

That was probably an unnecessary attempt at bonding. Those are not in contact with the circulating water.

- YouTube :shock:

;-):wink:

I agree, it’s unnecessary in this case.

From the 2011 NEC on Hydromassage tubs,

**[FONT=Times-Bold][size=2]680.74 Bonding. **[/size][/FONT][FONT=Times-Roman][size=2]All metal piping systems and all grounded
metal parts in contact with the circulating water shall be
bonded together using a solid copper bonding jumper, insulated,
covered, or bare, not smaller than 8 AWG. The bonding
jumper shall be connected to the terminal on the circulating
pump motor that is intended for this purpose. The bonding
jumper shall not be required to be connected to a double insulated
circulating pump motor. The 8 AWG or larger solid
copper bonding jumper shall be required for equipotential
bonding in the area of the hydromassage bathtub and shall not
be required to be extended or attached to any remote panelboard,
service equipment, or any electrode. The 8 AWG or
larger solid copper bonding jumper shall be long enough to
terminate on a replacement non-double-insulated pump motor
and shall be terminated to the equipment grounding conductor
of the branch circuit of the motor when a double-insulated
circulating pump motor is used.

What is shown is neither a metallic piping system nor in contact with the circulating water.
[/size][/FONT]

I always had a question regarding the reference to “solid copper” in this standard and exactly what the term means…

I have always interpreted it as meaning “not multi-stranded”, but it could mean “not spliced”, “not clad”, or all of the above (probably the correct answer).

If the standard excludes stranded wire, can someone explain why? Inquiring minds want to know.

I agree also, but how many times have you seen a bonding jumper to the metallic hot and cold water pipes feeding the tub faucet?

Chuck, solid means not stranded. Continuous would mean without a splice.

I don’t know the reason for solid vs stranded but have heard it had to do with it lasting longer than the stranded. I guess surface area plays a part.

Grounding is a connection to earth. In 250.4(A)(1) we learn why we make a connection to earth. In this section there are four reasons mentioned. 1- Lightning. 2- Power surges. We need to know the difference between surges and spikes. 3- Unintentional contact with higher voltage lines. 4- To keep everything stable.
These four reasons are the only reasons we connect to earth. The stray voltages has nothing in this world to do with this requirement as no electron is seeking earth nor does it leak to earth.

Bonding; There is two different types of bonding. First we want to bond any and all non-current carrying metal to the service neutral. This bonding is what causes the breaker or fuse to open not the earth connection. This bonding is accomplished by the use of the equipment grounding conductor be it a conductor or the metal raceway in which the conductors are installed.
By using a conductor or metal raceway we are installing a low impedance path for any fault current to travel back to its source. In the service disconnect enclosure (main panel) the equipment grounding conductors are “bonded” to the same terminal bar as the neutral conductor. In the event of a fault the outcome would be the same as touching the hot conductor to the neutral conductor at some outlet. The overcurrent device will open.

The earth connection will not open an overcurrent device. Using Ohm’s Law we can check this statement. If we have 25 ohms on our ground rod using Ohm’s Law we can see that 120/25=4.8 amps and nowhere close to enough current to open the breaker or fuse. This is proof that the grounding electrode is not installed to open the overcurrent device.

The second bonding is equipotential bonding. This bonding is done to make everything in a certain area at the same potential such as we find around bodies of water such as pools and tubs. This bond does not have to connect to anything except anything in the area needing protection such as metal and or water.
Someone in a swimming pool that has the water at a potential of 120 volts above earth with everything bonded will be in no danger at all as everything that can be touched will be at the same potential. In the classroom I refer to this equipotential bonding as the Faraday Cage. Google the Faraday Cage for a better understanding of equipotential bonding.

This is what equipotential bonding is all about

Here is a pic from the code check illustrations. Not so sure about Ben and the rubber ducky!!

Since that water pipe is not part of the water circulation system the bonding jumper is not required.

I’m not sure I agree, although I am open to being wrong :smiley:

I read the intent as two different requirements for bonded components.

  1. All metal piping systems (and)
  2. All grounded metal parts in contact with the circulating water

shall be bonded together using a solid copper bonding jumper, insulated,
covered, or bare, not smaller than 8 AWG.

Your interpretation (I assume) would be the following;

  1. All metal piping systems in contact with the circulating water (and)
  2. All grounded metal parts in contact with the circulating water

shall be bonded together using a solid copper bonding jumper, insulated,
covered, or bare, not smaller than 8 AWG.

What say you?

I agree with the green. :slight_smile:

There should be a change coming in the 2014 NEC to clarify this requirement. I will post the proposal later.

You’re light years ahead of me. CA is still using the 2008 NEC.

I am very interested in the clarification you mentioned. I will be patiently waiting :slight_smile:

Thanks Jim. Been wondering if that was what they really meant for years.

680.74 has always been a misunderstood code section. Many believe that like pools and spas there a requirement for equipotential bonding in the vicinity of the tub. There is no requirement to bond metal parts or metal piping systems that are not in contact with the water circulation system. Even an article in the IAEI magazine a few years ago got it wrong. This proposal for the 2014 NEC which has been preliminarily accepted should clear up the confusion.


That has been my understanding.

Besides not being required, do you believe that such a bond is unnecessary?