Insta hot requiring double circuits

[JohnDS]

Hey guys. An insta hot that mounts under sink. It is requiring two 40amp circuits as opposed to one 80amp circuit. It is located in an apartment that is detached from main house (separate structure). Plan is to run pipe from main house panel to detached apartment and run thhn through. Im thinking i should run 4 hots, 2 neutrals, 2 egc's. Is this overkill?
1) Can I share an egc.
2) Can i share a neutral?
3) Since this is a detached building, it requires a disconnect, correct?

Below is a photo of nameplate.

I really appreciate your help guys, thanks.



Sent from my SAMSUNG-SM-G730A using Tapatalk

 

[GoldDigger]

Since the unit requires 240 VOITS (?!), it probably will not be drawing much if any current from either neutral.

The NEC allows you to run just the four L1A, L2A, L1B, L2B conductors plus the EGC if you choose wire rather than raceway EGC.
You do not have to run any neutral unless the unit has a terminal for it.
And if it does, you may only need to run one neutral for whichever branch has the neutral connection.
If both branch terminal sets in the unit have neutral connections, you must run separate neutrals for each branch circuit.
But you may be able to justify a reduced size neutral.

To supply two heaters and whatever lighting and general purpose is needed, you will have to put a subpanel at the building. (There is a limit on the number of branch circuits that can feed one outbuilding.
And you will need a disconnect for the building, which might be the main breaker in the subpanel. You will also need a ground electrode or two for the building in addition to the EGC run with the feeder.

 

[Buck Parrish]

What size panel is in the separate structure now ? The best thing to do is up size the existing panel . Most Water heaters don't require a neutral.

 

[GoldDigger]

What size panel is in the separate structure now ? The best thing to do is up size the existing panel . Most Water heaters don't require a neutral.

But the InstaHot (tankless, on demand) may have control circuitry powered from a 120V transformer or 120V AC to DC power supply. There is probably a fan too, which might run on 120V.

 

[JeffBabineaux]

Eco 18 installation guide here.

I'm still new at this, but why would you run 4 hots and 2 neutrals? I looked it up to see how the mfg suggests wiring it, and I see one hot, one neutral.


They specifically call for separate ground conductors for each incoming circuit. I'm reading that as separate egc's at the unit.

 

[infinity]

Eco 18 installation guide here.

I'm still new at this, but why would you run 4 hots and 2 neutrals? I looked it up to see how the mfg suggests wiring it, and I see one hot, one neutral.


They specifically call for separate ground conductors for each incoming circuit. I'm reading that as separate egc's at the unit.

I see 2-40 amp, 240 volt circuits and one EGC if contained in the same raceway or cable (5 conductors no neutral required).

 

[JohnDS]

I see 2-40 amp, 240 volt circuits and one EGC if contained in the same raceway or cable (5 conductors no neutral required).

Can the egc still be the same size as other conductors?

Does this need to be gfci protected?

Sent from my SAMSUNG-SM-G730A using Tapatalk

 

[GoldDigger]

... and I see one hot, one neutral.
...

The diagram in the PDF shows two hots (L1 and L2) and no neutral for each of the two circuits.
If you run each in separate raceway, you will get two raceway EGCs. If you run wires in one common raceway, that will give you one raceway EGC which as a practical matter should be as good as two wire EGCs. If you put in a wire EGC, you may want to have it double the size of the branch conductors. If you run NM or similar, you need a wire EGC in each run of NM since the EGC needs to be the same ampacity as the ungrounded wires. One wire EGC in 40A NM for two 40A branch circuits would not be enough.

 

[Sierrasparky]

That ain't no insta hot. That is a tankless electric water heater
As others say ,
4 hots and a EGC.
Also you will need to consider the size of the Electrical service.
If this is the water heater for a separate dwelling then you need to consider a properly sized sub panel for all the dwelling circuits. Check with your local AHJ.

 

[don_resqcapt19]

...
To supply two heaters and whatever lighting and general purpose is needed, you will have to put a subpanel at the building. (There is a limit on the number of branch circuits that can feed one outbuilding.
...

Yes, there is a limit and that limit is one branch circuit or one feeder.

225.30 Number of Supplies
A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E). ...

I don't see anything in 225.30(A)-(E) that permits more than one circuit for this application.

 

[JohnDS]

.

 

[JohnDS]

Thank you all. I have a few more questions so I apologize in advance if I am not understanding entirely. From what I understand, I will be running 4 hots and 1 EGC in the pipe run. One of you gentleman recommended doubling the the EGC size according to the size of the ungrounded conductors:

1) I figured to use #6s to compensate for voltage drop of a 200' run as opposed to #8s. Should I double the size of the EGC to a #3 because #6s are being used for voltage drop, or double the size of the EGC to a #4 because #8s would have been used if votage drop was not an issue?

2) Does this application require gfci protection?

3) Does this application require a disconnect in detached structure?

 

[don_resqcapt19]

Thank you all. I have a few more questions so I apologize in advance if I am not understanding entirely. From what I understand, I will be running 4 hots and 1 EGC in the pipe run. One of you gentleman recommended doubling the the EGC size according to the size of the ungrounded conductors:

There is no reason for the EGC to be larger than the circuit conductors.

1) I figured to use #6s to compensate for voltage drop of a 200' run as opposed to #8s. Should I double the size of the EGC to a #3 because #6s are being used for voltage drop, or double the size of the EGC to a #4 because #8s would have been used if votage drop was not an issue?

If you upsize the circuit conductors, you also have to upsize the EGC in the same proportion. A 40 amp OCPD normally requires a #10 EGC and a #8 circuit conductor. A #8 is 16510 circular mils, a #6 is 26240. 26240/16510 =1.589 A #10 (the normal size EGC for a 40 OCPD must be increased in circular mil area by 1.589. The area of #10 is 10380 so when you multiply by the 1.589, the minimum size of the EGC becomes 16493, requiring a #8 EGC.

2) Does this application require gfci protection?

No.

3) Does this application require a disconnect in detached structure?

Yes it does, but you are still not permitted to feed the detached structure with more than one circuit. The only code compliant way to feed these new loads is to install a feeder from the first building and a "sub-panel" in the detached structure.

 

[stickboy1375]

I would pull one feeder sized accordingly, and use a 4 circuit
panel to supply the appliance...

 

[JohnDS]

There is no reason for the EGC to be larger than the circuit conductors.

So this is still the case even though there are 4 hots on 2 separate 40a breakers?

Sent from my SAMSUNG-SM-G730A using Tapatalk

 

[don_resqcapt19]

So this is still the case even though there are 4 hots on 2 separate 40a breakers?

Sent from my SAMSUNG-SM-G730A using Tapatalk

See 250.122(C).

You still have to address the fact that the code does not permit your proposed installation. You are not permitted to run more than one branch circuit or feeder to a detached building.

 

[Sierrasparky]

Thank you all. I have a few more questions so I apologize in advance if I am not understanding entirely. From what I understand, I will be running 4 hots and 1 EGC in the pipe run. One of you gentleman recommended doubling the the EGC size according to the size of the ungrounded conductors:

1) I figured to use #6s to compensate for voltage drop of a 200' run as opposed to #8s. Should I double the size of the EGC to a #3 because #6s are being used for voltage drop, or double the size of the EGC to a #4 because #8s would have been used if votage drop was not an issue?

2) Does this application require gfci protection?

3) Does this application require a disconnect in detached structure?

See 250.122(C).

You still have to address the fact that the code does not permit your proposed installation. You are not permitted to run more than one branch circuit or feeder to a detached building.

Your installation suggestion is not complaint as others have stated.
The question regarding conductor size and EGC are irrelevant to your scenario IF run from the main structure as you are only permitted 1 MWBC or one feeder. Furthermore a 4 circuit load center will probably be insufficient as there are other loads and circuits to this detached dwelling.
The wire size suggestion would be relevant feeding from a load center in/at the detached structure.

You will need to size a feeder to all the loads in the structure , that involves lighting, cooking , appliance , and general use receptacles.
This will probably put you over a 100amp panel as per manufactures specs.

Good luck.

You can choose to not listen to us and that is your perogotive but in the end it is your neck on the line.

 

[JohnDS]

Your installation suggestion is not complaint as others have stated.
The question regarding conductor size and EGC are irrelevant to your scenario IF run from the main structure as you are only permitted 1 MWBC or one feeder. Furthermore a 4 circuit load center will probably be insufficient as there are other loads and circuits to this detached dwelling.
The wire size suggestion would be relevant feeding from a load center in/at the detached structure.

You will need to size a feeder to all the loads in the structure , that involves lighting, cooking , appliance , and general use receptacles.
This will probably put you over a 100amp panel as per manufactures specs.

Good luck.

You can choose to not listen to us and that is your perogotive but in the end it is your neck on the line.

I do appreciate all responses. I appologize if you feel my question regarding conductor sizing and EGCs is irrelevant because the particular scenario the installation was in does not meet code requirements. It was not my intention to disregard or not acknowledge code, rather i was taking all this helpful information in and continued moving forward. Since I was informed of the proper code requirements, I continued to ask about the proper sizing and number of EGCs for two 240v circuits running to one device because it now will be code compliant. Hope that clears things up. Thanks again guys for all the responses.

Sent from my SAMSUNG-SM-G730A using Tapatalk

 

[Little Bill]

I do appreciate all responses. I appologize if you feel my question regarding conductor sizing and EGCs is irrelevant because the particular scenario the installation was in does not meet code requirements. It was not my intention to disregard or not acknowledge code, rather i was taking all this helpful information in and continued moving forward. Since I was informed of the proper code requirements, I continued to ask about the proper sizing and number of EGCs for two 240v circuits running to one device because it now will be code compliant. Hope that clears things up. Thanks again guys for all the responses.

Sent from my SAMSUNG-SM-G730A using Tapatalk

First off, going away from your original questions, you might want to suggest to your customer:

1.) Change the tankless to a gas version rather than the "energy hog" electric version.

2.) Just put an electric tank water heater in.

Now back to your questions.


You never said how the other items in the building were being powered. If there is a panel in there already, is it not large enough to handle the extra load? Or is the feeder to it not large enough?
If it's just the panel then you could change that, but if it's the feeder then you have no choice but to run a larger feeder and increase the size of the subpanel.

Now since you acknowledged that your original proposal was not code compliant, here is another stickler for you. IF there is already a feeder to the building for the other items, you can't run another feeder to it. You're only choice is to pull out/abandon the current feeder and run one large enough for your loads (including your added WH).
Along the same lines, if there is only a branch circuit or MWBC feeding the building, it would also have to be removed/abandoned.

In a "nut shell", to do what you want will require a panel (subpanel) in the building and feeder conductors large enough to carry the load.

As to running your circuit, you only need to run one EGC with the two 40A circuits. And as has been stated, you don't need to increase the size unless you are up-sizing the other conductors.
No GFCI required.

 

[Sierrasparky]

I do appreciate all responses. I appologize if you feel my question regarding conductor sizing and EGCs is irrelevant because the particular scenario the installation was in does not meet code requirements. It was not my intention to disregard or not acknowledge code, rather i was taking all this helpful information in and continued moving forward. Since I was informed of the proper code requirements, I continued to ask about the proper sizing and number of EGCs for two 240v circuits running to one device because it now will be code compliant. Hope that clears things up. Thanks again guys for all the responses.

Sent from my SAMSUNG-SM-G730A using Tapatalk

No worries, just thought that what we were saying was not getting through. I had a couple customers this week that were a bit abusive.