No neutral to panel supplying 240v-only loads, right?

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LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I am proposing to upgrade a residential service by adding a second 200a panel that will be used only to supply a tankless water heater that uses four 40a circuits. The service has an exterior main disconnect next to the meter, so we're talking about a 400/320a meter base and a second 200a disconnect.

Just want to confirm that I can use SE and not SER, the neutral gets bonded/grounded in the new disconnect, and need go no farther. But, I do need to add GECs to the new disconnect, and cannot depend on the existing ones in the present disconnect, right?
 
Yes. SE is okay

The new GEC can just be tagged onto the other existing GEC assuming that GEC is sized for the service conductors.

You do not have to take the nec GEC to the electrode.

The new GEC need only be sized to the conductors feeding it.

This sorta shows what I mean about the GECs


GECtaps.JPG
 
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Presume I add a second 4-0 al service cable, no service conductors will carry more than 200a (160 in theory), nor be larger than 4-0 al. If the POCO enlarges the lateral ahead of the meter, does that increase affect me?

Presume also I find that the present service has the expected #4 to water piping and #6 to driven electrodes: Will I need to add another #4 to the water pipe, or replace the #4 with a single larger GEC after joining the two #4s?

Can a single #6 be used for both disconnects to the driven electrode using, say, a split bolt, or must I add another from the new disconnect to the rods?
 
LarryFine said:
Presume I add a second 4-0 al service cable, no service conductors will carry more than 200a (160 in theory), nor be larger than 4-0 al. If the POCO enlarges the lateral ahead of the meter, does that increase affect me?

Presume also I find that the present service has the expected #4 to water piping and #6 to driven electrodes: Will I need to add another #4 to the water pipe, or replace the #4 with a single larger GEC after joining the two #4s?

Can a single #6 be used for both disconnects to the driven electrode using, say, a split bolt, or must I add another from the new disconnect to the rods?
Click to expand...



So a 400A service riser to 400A meter base to disco to existing panel. Existing panel has GECs, 4 to water, 6 to rods. New panel comes off disco or meter base? I am a little unclear on exact set up.

Answer above may determine water pipe GEC size and connections.

Yes, #6 for new panel can tag onto old #6 with split bolt.
 
Cool.

Docs320Ametersocket.jpg


P1 is left one, #4 to water and #6 to rods. Existing.

P2 is new. 4/0 SE, #6 to #6 from P1-split bolt.

For P2 easiest for water is just a new #4 to water pipe, otherwise you would have attach both #4 to a GEC sized to 600 kcmil main service conductors and use irreversible connections.
 
Check with poco 320a not 400a you will need to have a main disconnect protecting poco feed from your load.
Drop, meter, disco, your (2) 200a loads.
 
single disconnect

single disconnect

Have you considered supplying the second panel from the existing disconnect? I believe there are double lugs available? Will the POCO actually come out and provide 400 amps?
 
jumper said:
No, discos are grouped and you are allowed up to 6.

Meter base is 320A continuous or 400A combined.
Click to expand...

I know, but I bid and won a temp. power job few years back and had to because the poco would not hit it until we changed it by adding a "main disco ", 400a disco not cheap, was pissed.
 
Greg1707 said:
Have you considered supplying the second panel from the existing disconnect?
Click to expand...
That's basically how the existing sub-panel is wired now (installation not by me). First, the four elements tripped the 125a sub-panel feeder breaker, unless one was turned off, which wasn't enough to heat winter incoming water temps.

To get around that, the other guy moved one of the four heater breakers into the main panel, which means that, now the main breaker trips (unless again any one 40a breakers is off, again reducing the load to three heating elements.

I believe there are double lugs available? Will the POCO actually come out and provide 400 amps?
Click to expand...
Yes, although they call it a 320a service, reflecting the maximum 80% continuous rating, and does come with double lugs, to supply two 200a disconnects.
 
I almost forgot to update this. Had my inspection yesterday. The inspector said that I had to use SER instead of SE for the feeder, even though the loads are only line-to-line. I explained that the neutral could stop at the exterior disconnect, but he said that, because it's a feeder, the neutral had to be run to the interior panel. I told him I would consult the code and get back to him.

He said that he's never heard of a feeder without a neutral in 20+ years of inspecting and agreed to call the head inspector (whom I know) for his opinion. The head inspector agreed with the inspector, and also never heard of a feeder with no neutral. As the inspector was typing the failure on his laptop, the head inspector called back and said that I was correct. That made my day!
 
4/0 alum is the largest service entrance conductor that enters the building and 4/0 alum is the largest service entrance conductor terminating at a service disconnect located at the service equipment.

Based on 250.66 a #4 GEC would be the largest size common GEC needed under that circumstance

Under those conditions it is not necessary to run a second # 4 GEC from the new panel to the water with in 5 ft of building entrance. just tap the original #4 GEC the same as you are tapping the # 6 to the rods

Also if it was necessary to increase the size of the grounding electrode conductor for the grounding electrode system you could not parallel two conductors smaller than 1/0 AWG
 
david said:
4/0 alum is the largest service entrance conductor that enters the building and 4/0 alum is the largest service entrance conductor terminating at a service disconnect located at the service equipment.

Based on 250.66 a #4 GEC would be the largest size common GEC needed under that circumstance

Under those conditions it is not necessary to run a second # 4 GEC from the new panel to the water with in 5 ft of building entrance. just tap the original #4 GEC the same as you are tapping the # 6 to the rods

Also if it was necessary to increase the size of the grounding electrode conductor for the grounding electrode system you could not parallel two conductors smaller than 1/0 AWG
Click to expand...
You replying to this thread or some other thread?:?
 
LarryFine said:
Presume I add a second 4-0 al service cable, no service conductors will carry more than 200a (160 in theory), nor be larger than 4-0 al. If the POCO enlarges the lateral ahead of the meter, does that increase affect me?

Presume also I find that the present service has the expected #4 to water piping and #6 to driven electrodes: Will I need to add another #4 to the water pipe, or replace the #4 with a single larger GEC after joining the two #4s?

Can a single #6 be used for both disconnects to the driven electrode using, say, a split bolt, or must I add another from the new disconnect to the rods?
Click to expand...

kwired said:
You replying to this thread or some other thread?:?
Click to expand...

This thread
 
LarryFine said:
I almost forgot to update this. Had my inspection yesterday. The inspector said that I had to use SER instead of SE for the feeder, even though the loads are only line-to-line. I explained that the neutral could stop at the exterior disconnect, but he said that, because it's a feeder, the neutral had to be run to the interior panel. I told him I would consult the code and get back to him.

He said that he's never heard of a feeder without a neutral in 20+ years of inspecting and agreed to call the head inspector (whom I know) for his opinion. The head inspector agreed with the inspector, and also never heard of a feeder with no neutral. As the inspector was typing the failure on his laptop, the head inspector called back and said that I was correct. That made my day!
Click to expand...
My confusion was that larry posted nearly identical reply to what is quoted in this post in another thread, and I thought I was reading that thread. Sorry about that.
 
david said:
Also if it was necessary to increase the size of the grounding electrode conductor for the grounding electrode system you could not parallel two conductors smaller than 1/0 AWG
Click to expand...

Where in the NEC does it say that you can parallel two smaller conductors when a single larger GEC is required?
 
"For P2 easiest for water is just a new #4 to water pipe, otherwise you would have attach both #4 to a GEC sized to 600 kcmil main service conductors and use irreversible connections."

infinity said:
Where in the NEC does it say that you can parallel two smaller conductors when a single larger GEC is required?
Click to expand...

When paralleling two conductors together you have what is defined as a single conductor do you not, so where does the NEC say two conductors 1/0 and larger cannot be paralleled to form a single conductor?
 
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