200' supply to sub panel.

[kspousta]

Hope this is the right place to post this. A search netted me some "confusing" answers so I hope you all can get me squared away..

Built a pool house out back. I need to put a 100A subpanel out there to power the pool equipment and the pool house itself. The run from the main panel (200A) is just about 200' and I've got 1.5" PVC conduit run already.

Since the pumps require 220V, I know I'll need two "hots" along with a neutral and a ground. 220 circuits will use double pole breakers, 110 circuits (GFCI) will need single pole breakers. I also know I need to keep the neutrals and grounds separate in the sub panel. I have some questions...

Do I need a ground rod at the subpanel or is the ground tie to the main panel sufficient?

What size feed wire to keep the voltage drop to a minimum? I read somewhere one should aim for no more than 3% drop..

To feed this subpanel, should I drop in a 100A breaker at the main, or use pass through lugs and put a 100A "main" breaker at the subpanel?

Total breakers at the subpanel will be 7.. Three 220s and one 110 for the pool equipment and three 110s for the pool house itself.

Am I on the right track here? Anything I missed or am completely incorrect on? I'm in CA BTW

Thanks!

 

[George Stolz]

I apologize for the delay caused in closing this thread.

Do I need a ground rod at the subpanel or is the ground tie to the main panel sufficient?

A Grounding Electrode System is required to be installed at all detached structures supplied by feeders and multiple branch circuits by 250.32(A).

What size feed wire to keep the voltage drop to a minimum? I read somewhere one should aim for no more than 3% drop..

The 3% figure is from FPNs scattered in a couple of places in the NEC. To determine the voltage drop, you need to examine how much current each load is using, and apply a voltage drop calculation.

To feed this subpanel, should I drop in a 100A breaker at the main, or use pass through lugs and put a 100A "main" breaker at the subpanel?

If your main panel is protected at 200A, then the feed through lugs of the main panel would also be protected at 200A, not 100A. You would have to employ the tap rules to try the feed throughs, I would sleep way better at night using a 100A breaker at the main and then also installing a main breaker panel at the detached structure to comply with 225.33(A).

One word of caution - hot tubs, pools and spas are very complicated, and should not be taken lightly. Be sure to have this work inspected, and read (and re-read) Article 680 to ensure a successful inspection.

 

[kspousta]

I apologize for the delay caused in closing this thread.

Completely understood. Should have mentioned I was a contractor at the outset but this is not my specialty.

A Grounding Electrode System is required to be installed at all detached structures supplied by feeders and multiple branch circuits by 250.32(A).

I was told by a couple people that a GES was only required for a habitable building and another guy said something to the effect of the above. I figure shortest path to ground is a GES instead of almost 200' of copper so I plan on a GES when I rough in the pool house on Monday.

The 3% figure is from FPNs scattered in a couple of places in the NEC. To determine the voltage drop, you need to examine how much current each load is using, and apply a voltage drop calculation.

I found a similar calculator online this afternoon and after figuring loads, it told me a couple #2 THHN conductors would net me 2.78% loss.. I'm going to pull a third #2 for the neutral and a #6 for ground with a ground rod at the pool house. If I did the math right, my fill factor is roughly 0.39, well under the > 2 wire 40% limit of 0.814 limit for 1.5" conduit.

If your main panel is protected at 200A, then the feed through lugs of the main panel would also be protected at 200A, not 100A. You would have to employ the tap rules to try the feed throughs, I would sleep way better at night using a 100A breaker at the main and then also installing a main breaker panel at the detached structure to comply with 225.33(A).

Yep, picked up the materials at Graybar this afternoon and I'll pull wire and get the subpanel end hooked up in the morning. I won't energize the thing until it's inspected (Yes, this whole project is permitted in case anyone's wondering) and I can secure the subpanel.

One word of caution - hot tubs, pools and spas are very complicated, and should not be taken lightly. Be sure to have this work inspected, and read (and re-read) Article 680 to ensure a successful inspection.

Yep. Pool contractor's electrician is dealing with the gear. I'm just providing the subpanel and they can tie in to it when the feed's inspection has passed.

If anyone sees anything glaringly wrong with my plan, please let me know.. I need to have this thing done by June 1..

Thanks!

-K

 

[George Stolz]

Completely understood. Should have mentioned I was a contractor at the outset but this is not my specialty.

I appreciate your patience.

I was told by a couple people that a GES was only required for a habitable building and another guy said something to the effect of the above.

To seal the deal in my favor, check out the definition of "structure" in Article 100, and then re-read 250.32(A) - A 4x4 post in the ground with a panel on it is a structure.

I figure shortest path to ground is a GES instead of almost 200' of copper so I plan on a GES when I rough in the pool house on Monday.

Careful with your thinking - manmade electricity is seeking all paths back to it's source; it is not seeking the easiest path back to earth. Earth is only another path back to the serving transformer, not the end of the road.

-Grounding is connecting to the earth, this is done for lightning.
-Bonding is the connection of equipment to create an effective ground fault current return path, to quickly open the circuit breaker in the event of a fault.
-Equipotential bonding (680.26) is the bonding of equipment together to ensure that no matter what voltage the equipment is compared to more distant points, the voltage measured among the bonded equipment is as close to zero (to each other) as humanly possible.

If anyone sees anything glaringly wrong with my plan, please let me know.

Based on the information given, I see nothing else. But there's a lot we can't see from here.

 

[Dennis Alwon]

IMO you need a 100 amp breaker at both ends in your situation. Actually, if the load is light you can use a 60 amp breaker at both ends-- this will save you some money.

Also 2 ground rods should be driven at the pool panel at least 6 foot apart.

The gec should be connected to the isolated ground bar.

 

[1793]

Pools aren't my specialty either but I'm always learning.

I may have missed this but if not, don't you need to have an insulated EGC to the pool sub-panel?

 

[kspousta]

Dennis,

Breakers at both ends for sure. Going to double check loads and size 'em accordingly.

Pools aren't my specialty either but I'm always learning.

I may have missed this but if not, don't you need to have an insulated EGC to the pool sub-panel?

Not sure. I'll do some investigating and find out.

Thx

 

[Dennis Alwon]

Dennis,
Not sure. I'll do some investigating and find out.

Thx

You will need an insulated ground to the pool panel. 680.25

 

[wbalsam1]

IMO you need a 100 amp breaker at both ends in your situation. Actually, if the load is light you can use a 60 amp breaker at both ends-- this will save you some money.

Also 2 ground rods should be driven at the pool panel at least 6 foot apart.

The gec should be connected to the isolated ground bar.

You mean to connect the grounding electrode conductor to the equipment grounding bar, not to the isolated neutral bar, right? :smile:

 

[Dennis Alwon]

You mean to connect the grounding electrode conductor to the equipment grounding bar, not to the isolated neutral bar, right? :smile:

Yes, of course- I never call a neutral bar a ground bar so sorry for the confusion. I used the word isolated to mean isolated from the neutral bar. Thanks for clarifying this for others.

 

[dbuckley]

Why 100A breakers at both ends? Surely only a disconnect required at the sub-panel if you have a breaker at the main panel...?

 

[LarryFine]

Why 100A breakers at both ends? Surely only a disconnect required at the sub-panel if you have a breaker at the main panel...?

I thought of asking the same question, but figured someone would say, "Because an MB panel is cheaper than a disco and separate ML panel," so I didn't.

 

[stickboy1375]

I thought of asking the same question, but figured someone would say, "Because an MB panel is cheaper than a disco and separate ML panel," so I didn't.

My thoughts as well, and its usually how I do it.

 

[kspousta]

Whew! it's done. Got the feeders pulled and landed at both ends and roughed in the poolhouse today.. Other than a grounding rod, it's all done and ready for inspection.

Thanks for the input - it made today go very well indeed...