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Adding a ground to 6 3 awg

Posted by lthandy (My Page) on
Mon, Mar 2, 09 at 18:43

I have a new hot tub that requires a 6/3 220V supply with ground. I am going to naturally run a GFCI box for the tub to hook up to. The run from the main box is about 75 feet. I already have in place a 6/3 (no ground) wire that fed the electric dryer, (which I no longer need, having switched to gas drying) that pretty much reaches to where the hot tub will be located. Rather than abandoning that existing 6/3 wire, is it considered safe/acceptable/legal to simply run a 6G single green wire from the ground bar of the main to the new GFCI box's ground? This would save a pretty penny. Thanks, LT


Follow-Up Postings:

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RE: Adding a ground to 6 3 awg

Not acceptable. Run a new cable.


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RE: Adding a ground to 6 3 awg

No good as Joe said. I also bet that 6/3 is aluminum, am I right? There would be no reason ever to run #6CU to a dryer.

Pretty much every spa I have wired has specified copper conductors.


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RE: Adding a ground to 6 3 awg

No, actually it (the 6/3) is copper. May I ask what the difference is between the ground being bound inside the insulation, vs being run alongside it?..if it is simply a matter of sloppiness, would taping it to the 6/3 the whole way be acceptable? Thanks for the replies, guys.


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RE: Adding a ground to 6 3 awg

It is not a matter of slopiness, it is a matter of being incorrect on a number of levels.

Water, electricity, and people in the water is a recipe for disaster. Therefore spas and pools have numerous additional requirements in order to be wired properly and what it all comes down to is the lives of the people using the spa and/or pool.

What this all translates to is the need to run a new cable which would be 6/3 with ground - if anyone tells you differently, they are wrong.


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jmvd20

I understand that. I am not trying to be argumentative. I am simply trying to understand at a level that you seem to. Just humor me. In what way is a separate ground wire that is insulated and connected correctly at each end and even bound to the other 6/3 cable more of a danger to the people in the hot tub than if it is inside the cable? I fully accept that you are correct. I would just like to understand why. Anyone else is welcome to try to answer this as well. Thank you.


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RE: Adding a ground to 6 3 awg

I think that it would be a serious code violation. If someone were to get hurt you would be liable. That wouldn't be worth saving a few bucks to not run it correctly.


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RE: Adding a ground to 6 3 awg

It is in the code, that all conductors of a circuit must be in the same conduit or cable. It is a matter of theory. Conductors not together in the same cable will cause undesireable inductive effects. Also, the grounding wire not being run with the others will cause a delay in the circuit breaker opening on a short circuit due to induction.


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RE: Adding a ground to 6 3 awg

Got it..thanks joefixit.


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RE: Adding a ground to 6 3 awg

Does the spa really require the neutral? Many don't.


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RE: Adding a ground to 6 3 awg

lthandy: "In what way is a separate ground wire that is insulated and connected correctly at each end and even bound to the other 6/3 cable more of a danger to the people in the hot tub than if it is inside the cable?"

If the separate ground wire is bound to the other cable then the difference is trivial. With due respect to joefixit2, from a physics standpoint the claims are untrue. The added inductance is trivial. As for the NEC, it's a little ambiguous as to whether it's OK in general to simply run the grounded conductor in the same raceway as opposed to the same cable. In any case, there is a specific exception for existing installations, 300.3(B)(2). Save the money by running a separate ground wire, as long as it is adequately protected. NEC article 680 covers specifics for this application, with grounding in 680.6 and 680.7. Mainly they refer to the general grounding section. Of course the important thing here is to have proper GFCI protection.


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RE: Adding a ground to 6 3 awg

Wow cvf938, you just tried to nullify everything that four or five professionals have stated.

NO, it is NOT ok to just tape the ground to the outside of the cable.

Your example of 300.3(B)(2) holds no water either. That is for very specific conditions like adding a ground to receptacles (does not apply here) and bonding (limited to 6').
I suggest you go back and read the whole thing.

Hopefully lthandy is done by now and will not be able to follow your incorrect advice.


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RE: Adding a ground to 6 3 awg

I assume this is going to be outside as well? Then you have other cabling issues as well.

As pointed out, you can't do this legally and the number of problem items continues to grow as more details come out.


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RE: Adding a ground to 6 3 awg

With due respect to you as well, petey_racer, you haven't presented any evidence either. The code section is relevant because this situation is exactly the replacement of a non-grounding receptacle.

"Equipment grounding conductors shall be permitted to be installed outside a raceway or cable assembly where in accordance with the provisions of 250.130(C) for certain existing installations..."

"For replacement of non-grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C)."


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RE: Adding a ground to 6 3 awg

I'm not sure how can interpret it that way, but OK. I'll try to clarify for you.

300.3(2) Grounding and Bonding Conductors. Equipment grounding conductors shall be permitted to be installed outside a raceway or cable assembly where in accordance with the provisions of 250.130(C) for certain existing installations or in accordance with 250.134(B), Exception No. 2, for dc circuits. Equipment bonding conductors shall be permitted to be installed on the outside of raceways in accordance with 250.102(E).

250.130(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:........

250.102(E) Installation. The equipment bonding jumper shall be permitted to be installed inside or outside of a raceway or enclosure. Where installed on the outside, the length of the equipment bonding jumper shall not exceed 1.8 m (6 ft) and shall be routed with the raceway or enclosure. Where installed inside a raceway, the equipment bonding jumper shall comply with the requirements of 250.119 and 250.148.

1) This is absolutely NOT a receptacle replacement or a "branch circuit extension". It is no longer a dryer receptacle circuit. It is now an existing ungrounded circuit to be used for another purpose.

2) This is not DC so 250.134(B) is irrelevant.

3) This is NOT a bonding jumper as specifically described in 250.102(E) and is obviously longer than 6'.

You can try and justify it any way you want. I honestly think you would have an extremely hard time convincing an inspector or qualified electrician that this would be code complaint OR safe, especially considering the use of the circuit.


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Image

Image courtesy Mike Holt


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RE: Adding a ground to 6 3 awg

"If the separate ground wire is bound to the other cable then the difference is trivial. With due respect to joefixit2, from a physics standpoint the claims are untrue."

The reason for the strict limit on the wire length is to ensure that circuit inductance is NOT increased badly enough to slow the tripping of overcurrent devices.

All you need to do is have a long enough length of a separate conductor that gets iron (beams, studs, etc.) in the 'loop area' between the conductors and a lot of bad things happen quickly.

You might not think that having phase conductors entering a steel enclosure through separate holes would have much affect either, but if the currents are large enough heating of the metal can occur.
The 'fix' is to cut a slot in the enclosure walls connecting the separate holes. The slot increases the reluctance ('magnetic resistance') of the magnetic circuit and eliminates the heating affects.


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RE: Adding a ground to 6 3 awg

Thanks for your feedback petey_racer. We'll agree to disagree then. I believe this qualifies as replacement of an ungrounded receptacle. The exception is granted to avoid the large expense of rewiring. As you note, it could come down to the particular inspector involved.

brickeyee, I'm not disputing that if you go crazy with the ground routing you could generate some inductance effects, mostly quite subtle. But I stand by the claim that with respect to safety and physics, binding the ground wire to the non-grounded cable is virtually indistinguishable from running 4-wire cable as long as the ground wire has adequate physical protection. This was lthandy's question.


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RE: Adding a ground to 6 3 awg

I would agree that if Professional Engineers and persons familiar with the intracacies of electrical transmission theory were the only persons installing wiring, then the NEC could probably allow more flexibility in wiring arrangements. In the real world, we need to observe the NEC.


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RE: Adding a ground to 6 3 awg

No argument, kurto. But I believe that exaggeration and obfuscation in the interest of greater good actually results in less compliance with and respect for any code.


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RE: Adding a ground to 6 3 awg

Hi Ithandy I would suggest you run the ground wire but you must install a circuit breaker panel at the end of the wiring. use only a no fault breaker that's what you should be using anyway and bond both ground and neutral in the panel box. But that will not help in cast. That's only if there is difficulty running the new wire.


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RE: Adding a ground to 6 3 awg

What colour are the wires inside the cable? If one of them is not white then that is another reason you can't use it. Many of those cables only had two insulated wires a bare or braided ground.


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RE: Adding a ground to 6 3 awg

cstaw,

A) WHAT are you talking about? What you are saying makes no sense.

B) This thread is a YEAR old. I bet he is done by now.


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