I see this frequently....the lug on the motor gets overlooked and no equipment ground gets pulled to the source of power. Home owner wants to know what can be done to ground the tub without installing a ground back to the panel. The motor is plugged into a GFCI, and there are no copper plumbing pipes around.
Jet Tub Motor Grounding
- Thread starter euclid43
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stickboy1375
Senior Member
- Location
- Litchfield, CT
You are talking about two things here, bonding, and grounding.... are you saying the motor lug isn't bonded, or there is no equipment ground at the receptacle?
For the bonding aspect, it doesn't get overlook, i've never come across a tub that was required to be bonded... meaning the pipes in contact with just the circulating water are always plastic.
check out 680.74 Bonding.
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The hydromassage tub doesn't need to have the motor bonded if there is plastic water pipes serving the tub. A bond is needed if the piping system is metal but you would only need a jumper from the lug to the water pipe.
Ok...the code is unclear about bonding "double insulated" and "non-double insulated" motor. I assume the double insulated is not required to be bonded. However, if it's determined that the motor is non-double insulated, then I take an 8 AWG to the smaller GFCI equipment ground?
kwired
Electron manager
- Location
- NE Nebraska
The lug you are talking about is not for landing the required equipment grounding conductor that must be run with the branch circuit. It is for landing the bonding jumper that you may need to bond non other non current carrying metal objects in the area. Minimum size of this jumper is 8 AWG no matter what size equipment grounding conductor supplies the unit. Quite often there is no additional items that need to be bonded.
From 680.74:
From 680.74:
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kwired
Electron manager
- Location
- NE Nebraska
Equipment ground is already bonded to that lug, it is for bonding other metal objects in contact with the water - which doesn't happen all that often which is why you never see the lug used.
kwired
Electron manager
- Location
- NE Nebraska
Not only are we assuming, the cord is required to contain the equipment grounding conductor unless a double insulated system of insulation is used.
If double insulated motor is used then the lug must still be connected to the EGC. I have never seen one like that, but am guessing the lug would be factory connected to the EGC anyway and likely may be required to be to meet listing requirements
kwired
Electron manager
- Location
- NE Nebraska
Go back to what I quoted in post #5.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I answered this question in post #2
#2 is vague and doesn't address what to do with the lug on the motor. There's code references for this, and the bottom line is that inspectors and installers should figure out what to do with motors that are double insulated and the only means of grounding is GFCI. Some illustrations want installers to go from the motor lug to the receptacle EGC, if that's the only source of grounding. Amazing.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I am assuming this is a hydromassage tub per your description. 680.74 is what you need to read. The bonding lug on the motor does not need to be used if the water system is plastic. Just supply a gfci circuit to a receptacle under the tub and you are done with it.-- If the water supply is metal than a bonding jumper from the motor lug to the water line is needed.
Now if there is a double insulated pump AND the water pipe is metallic then you would need to connect the #8 from the water pipe to the EGC of the pump.
Now if there is a double insulated pump AND the water pipe is metallic then you would need to connect the #8 from the water pipe to the EGC of the pump.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
There is no requirement to provide equipotential bonding for a hydro-massage tub. Only metal parts in contact with the circulating water and a metal water circulation system require the #8 bond.
kwired
Electron manager
- Location
- NE Nebraska
You are correct, I think I indicated items in area in one post and mentioned items in contact with the water in another post, slap me for not being consistant.
kwired
Electron manager
- Location
- NE Nebraska
What don't you understand? I think we explained the purpose of the lug in question more than once. It is not for landing the equipment ground from the branch circuit conductors, it is for bonding other objects in the area when required, that bonding jumper must be 8 AWG even if the equipment grounding conductor is only 14 AWG.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Actually there is a requirement for EPB. It is just that we think of the slabs, etc as the epb. The bonding of metal parts is an epb-- 680.74 specifically states epb.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Where in 680.74 does it say about equipotential bonding of surrounding metal parts or other metal piping systems?
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