Sizing a Ground wire

[Doubled33]

In accordance with the FMC thread.

Before you all say I should have pulled it at once I have 2 runs of pipe so I pulled one and waiting on the other.

I pulled 4 awg THHN for the two hots. I plan on pulling one more 4 for the neutral.

Total run length from panel to Gfci breaker is 71’

The spa says 6 awg min at 75 degrees. This looks like it is for the terminal block with the 2 hots and the neutral. The ground bus is separate and looks like a typical buss you would find in a panel with about 6 holes for wire.

I am out of 4 awg and need to buy new wire.

Can I pull a 8 for ground or does it need to be 6?

It is on a 50 amp breaker.

Thanks

 

[wyliesdiesels]

you can use green #10 for up to 60a breaker....

But the problem here is you increased the size of the ungrounded conductors beyond what they needed to be which is #8. so you have to increase the ground wire size proportionately to the increase of size of the ungrounded conductors.

so you now need #6 for the ground.

I wouldve used 3x #8s and a #10. youre making things harder on yourself and costing yourself a bit more money.

another issue you have is all circuit conductors need to be in the same conduit... so yes you should have pulled them all together...

 

[Doubled33]

you can use green #10 for up to 60a breaker....

But the problem here is you increased the size of the ungrounded conductors beyond what they needed to be which is #8. so you have to increase the ground wire size proportionately to the increase of size of the ungrounded conductors.

so you now need #6 for the ground.

I wouldve used 3x #8s and a #10. youre making things harder on yourself and costing yourself a bit more money.

another issue you have is all circuit conductors need to be in the same conduit... so yes you should have pulled them all together...

I already had the wire And did not have a use for it so it got used here.

I had the flex as well thus the parallel run thought.

I have seen parallel runs in different conduits. But…

I assume there are code sections that govern and I suspect there is something I did not follow….

Does it make a difference that both conduits are attached to a single gutter at each end then one larger pipe to the Gfci box and one larger pipe to the panel?

 

[wyliesdiesels]

wow sounds like a huge mess just to save a few bucks

all circuit conductors need to be in the same pipe...

are the terminals on the hot tub even rated for #4?

 

[sparky 1971]

If you're concerned about sizing the ground, you must want to do it right. Tear it out and start over. If using wire you already have is important then get a larger FMC. I wouldn't screw around with that though. Three #8 and a 10 ground will fit in a 3/4. Or even better might be a 6/3 NM.

 

[sparky 1971]

I already had the wire And did not have a use for it so it got used here.

I don't blame you for trying, but it made things worse overall. Had this info been given in the other thread, an attempt to stop you would have been made.

I had the flex as well thus the parallel run thought.

I have seen parallel runs in different conduits. But…

You didn't parallel anything. Parallel is running two or more sets of conductors. Lets pretend you wanted a 400 amp circuit. You could parallel two sets of 3/0 copper wires. (Two hot conductors for phase A. two for B, two for C (if three phase), two for the neutral, as well as two ground conductors. This would generally be done with two conduits, but one complete set of conductors would be in each conduit. I did an overhead 400 amp single phase service last winter and put everything in one 3", but had to bump up to 4/0 copper due to de-rating.

I assume there are code sections that govern and I suspect there is something I did not follow….

Yep, with what you have, everything should be in one conduit. And, even though you didn't actually parallel, if you had, the minimum conductor size for paralleling is 1/0.

Does it make a difference that both conduits are attached to a single gutter at each end then one larger pipe to the Gfci box and one larger pipe to the panel?

Nope.

 

[wyliesdiesels]

I already had the wire And did not have a use for it so it got used here.

I had the flex as well thus the parallel run thought.

I have seen parallel runs in different conduits. But…

I assume there are code sections that govern and I suspect there is something I did not follow….

Does it make a difference that both conduits are attached to a single gutter at each end then one larger pipe to the Gfci box and one larger pipe to the panel?

were they 1/0 or larger?

 

[Sumboodie]

FMC is?

Means Ford MotorCraft to me.

 

[sparky 1971]

FMC is?

Means Ford MotorCraft to me.

Flexible Metallic Conduit

 

[Doubled33]

I don't blame you for trying, but it made things worse overall. Had this info been given in the other thread, an attempt to stop you would have been made.


You didn't parallel anything. Parallel is running two or more sets of conductors. Lets pretend you wanted a 400 amp circuit. You could parallel two sets of 3/0 copper wires. (Two hot conductors for phase A. two for B, two for C (if three phase), two for the neutral, as well as two ground conductors. This would generally be done with two conduits, but one complete set of conductors would be in each conduit. I did an overhead 400 amp single phase service last winter and put everything in one 3", but had to bump up to 4/0 copper due to de-rating.

Yep, with what you have, everything should be in one conduit. And, even though you didn't actually parallel, if you had, the minimum conductor size for paralleling is 1/0.

Nope.

Thanks for the explanation.

Easy fix as I should be able to use the existing conduit to pull the new larger one in. A few KO plugs and all is well… or call the other conduit a spare.

 

[Doubled33]

wow sounds like a huge mess just to save a few bucks

all circuit conductors need to be in the same pipe...

are the terminals on the hot tub even rated for #4?

More than saving a few bucks. Electrical parts are ridiculously priced on the Island.

The data tag just says 6 awg min. I don’t see a max size listed however 4 will fit without a hair cut on the wire. Not sure if this makes it right or not…

Is it acceptable to run from the load side of the Gfci to the tub in number 6? That run is about 15’.

Will replace the other conduit to get all in one. Thanks for the knowledge…

 

[u2slow]

Seems unlikely the tub would require a full size neutral - maybe revisit that. Mine only needs a neutral for the light.

Do recheck the "#6 awg min" marking... usually terminals are fussier about a max size. I actually pigtailed my oversized feed down to #8. (Its a 40A nameplated tub).

And yes, I would consider a smaller wire for the last 15' stretch, if thats convenient/economical.

 

[dave*99]

Many many years ago I installed a hot tub in NJ. I remember the words "same size separately insulated ground" in the very specific instruction sheet my town supplied. It pertained to both spas and swimming pools. All my conductors were 6 gauge THWN in conduit. It was a 50A circuit.
YMMV