Hot water heater

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kwired

Electron manager
Location
NE Nebraska
My cousins husband worked power plants as an electrician. Never worked a house in his life. Different types of journeyman experience.
But they may have had a water heater in the plant, shop, break room....and he still figured it out at some point, or did he not do anything but production related work?;)
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
I've been thinking of what I may do when I get tired of this - but don't know much about golf:(

Sure you do!

You buy a box without KOs
Drill A hole in it, now you have ....................
"A hole in one"

How many holes do you need?

...............................FOUR!:lol:

Now schedule your tee time!;)
 

jap

Senior Member
Occupation
Electrician
Here is an even better one

2012-03-20_141846_wiring_diagrams_for_type%E2%80%9359t_therm-o-disc_thermostats_double_only.jpg

Notice contacts 2 and 4 in the upper limit switch toggle cannot be energized at the same time. That prevents both elements from being energized at the same time.

Much better one.
I'd of had to fire all of my journeyman if the 1st one was all they had to go by,since they'd of probably would have had to ohm out the contacts to see what did what and everyone should know that shouldnt they? ;)

Regardless this is not about troubleshooting just about information given or not given on a nameplate for sizing a circuit.

Jumpers comment of "connected load" put a lid on it a long ways back regardless of how the stats are wired.

jap>
 

GerryB

Senior Member
Much better one.
I'd of had to fire all of my journeyman if the 1st one was all they had to go by,since they'd of probably would have had to ohm out the contacts to see what did what and everyone should know that shouldnt they? ;)

Regardless this is not about troubleshooting just about information given or not given on a nameplate for sizing a circuit.

Jumpers comment of "connected load" put a lid on it a long ways back regardless of how the stats are wired.

jap>
I'll admit to not knowing the elements are "interlocked", never really troubleshooting one. I have changed my own element when I had electric hw and set the stat but it is not a common call around here to work on an electric HW heater, usually they are at the point to be replaced. So what I do know is I've have rarely seen one wired with larger than #10, and have seen them wired with #12. I have read the nameplates and seen the total connected load which is really all you need to know. In our area the POCO often has "off peak" in their meters for electric hot water. I am changing a service tomorrow (if the rain ends) where I have to add the 5th and 6th jaws in the meter socket for the off peak wires. By the way nice diagram. These off peak wires don't let the lower element heat when not needed. Any one else own up:)
 

kwired

Electron manager
Location
NE Nebraska
I'll admit to not knowing the elements are "interlocked", never really troubleshooting one. I have changed my own element when I had electric hw and set the stat but it is not a common call around here to work on an electric HW heater, usually they are at the point to be replaced. So what I do know is I've have rarely seen one wired with larger than #10, and have seen them wired with #12. I have read the nameplates and seen the total connected load which is really all you need to know. In our area the POCO often has "off peak" in their meters for electric hot water. I am changing a service tomorrow (if the rain ends) where I have to add the 5th and 6th jaws in the meter socket for the off peak wires. By the way nice diagram. These off peak wires don't let the lower element heat when not needed. Any one else own up:)
Are 5th and 6th jaws of the meter essentially going to a relay contact inside the meter which the output is controlled by something that determines when you have peak demand periods, with the intent for you to be able to shed loads of your choice to reduce total load during those periods?

Or are they separately metered output leads coming off this meter that are billed at a different rate and/or are still able to be controlled by POCO during peak demand periods.

"These off peak wires don't let the lower element heat when not needed." Doesn't sound quite right, if they are for load shedding during peak demand times then it should say something like " These off peak wires don't let the lower element heat during peak demand periods" Not letting it heat when not needed is more like when you see timers installed that kill power to the heater or maybe just the lower element to keep it from drawing power during non typical use periods - overnight, middle of day, etc.

Peak demand for POCO's usually is a time when several customers all have higher load simultaneously, and they are trying to find ways to encourage customers to cut back on some usage to prevent overloading their system.
 

GerryB

Senior Member
Are 5th and 6th jaws of the meter essentially going to a relay contact inside the meter which the output is controlled by something that determines when you have peak demand periods, with the intent for you to be able to shed loads of your choice to reduce total load during those periods?

Or are they separately metered output leads coming off this meter that are billed at a different rate and/or are still able to be controlled by POCO during peak demand periods.

"These off peak wires don't let the lower element heat when not needed." Doesn't sound quite right, if they are for load shedding during peak demand times then it should say something like " These off peak wires don't let the lower element heat during peak demand periods" Not letting it heat when not needed is more like when you see timers installed that kill power to the heater or maybe just the lower element to keep it from drawing power during non typical use periods - overnight, middle of day, etc.

Peak demand for POCO's usually is a time when several customers all have higher load simultaneously, and they are trying to find ways to encourage customers to cut back on some usage to prevent overloading their system.
From what I understand the off peak wires are a switch that interrupts the lower element, blue and yellow? The switch is turned on through the meter itself. This POCO the off peak contacts are open from noon to 8 PM, the bottom element will not heat up during those hours. From 8 PM until noon, when their residential rate is lower, the bottom element will heat until satisfied. So I had it backwards you're right.
 

kwired

Electron manager
Location
NE Nebraska
From what I understand the off peak wires are a switch that interrupts the lower element, blue and yellow? The switch is turned on through the meter itself. This POCO the off peak contacts are open from noon to 8 PM, the bottom element will not heat up during those hours. From 8 PM until noon, when their residential rate is lower, the bottom element will heat until satisfied. So I had it backwards you're right.
Never seen such a beast, but kind of what I expected.

Seems like it could introduce a lot of code issues to use it though.

First you would have to modify the factor wiring of the water heater to make it work. I don't have a problem with that, some AHJ's seem to get all bent out of shape when you modify something that is listed though, this would just be a stepping stone for more things to pick on once you start down this road.

Next thing that comes to mind is do you run these control(led) leads in a separate raceway or cable from the service conductors? Assuming it is essentially a switch loop through these two extra jaws - so that would make them non service conductors and they can't be in the same raceway/cable as the service conductors.

Next - even if they are permitted in same raceway, unless they are just signal wires they then would need to be counted as current carrying conductors for the purpose of ampacity adjustments.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Back in Illinois many years ago the bottom element of our water heater was fed not from the interlock contacts of the upper thermostat but rather from a second meter which was connected through a timer.
As a result it was possible to have both elements on if the upper one was on when the time clock turned on.
The second meter was billed at a lower rate and the primary meter billed a fixed rate independent of TOD.
 

jap

Senior Member
Occupation
Electrician
Back in Illinois many years ago the bottom element of our water heater was fed not from the interlock contacts of the upper thermostat but rather from a second meter which was connected through a timer.
As a result it was possible to have both elements on if the upper one was on when the time clock turned on.
The second meter was billed at a lower rate and the primary meter billed a fixed rate independent of TOD.

I take it the Water Heater had 2 sources of power from 2 different panels in that case.... correct?


JAP>
 

GoldDigger

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Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
The only thing fed from the second meter was the heater element, so as I recall it just had a fused disconnect after the meter, not a separate panel.
The main panel and the disco were inside the basement just below the meter outside.
(This was built before 1950, so no idea what the applicable code provisions were.)
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
(This was built before 1950, so no idea what the applicable code provisions were.)

DTE, in Detroit, still shows this in their billing rates: "This rate is available for customers who use an electric water heater for sanitary purposes. It requires a separate meter. Customers interested in this rate have several options and should call DTE Energy for more information."
 

peter d

Senior Member
Location
New England
From what I understand the off peak wires are a switch that interrupts the lower element, blue and yellow? The switch is turned on through the meter itself. This POCO the off peak contacts are open from noon to 8 PM, the bottom element will not heat up during those hours. From 8 PM until noon, when their residential rate is lower, the bottom element will heat until satisfied. So I had it backwards you're right.


What poco in CT still installs off peak metering? :huh:
 

GerryB

Senior Member
Never seen such a beast, but kind of what I expected.

Seems like it could introduce a lot of code issues to use it though.

First you would have to modify the factor wiring of the water heater to make it work. I don't have a problem with that, some AHJ's seem to get all bent out of shape when you modify something that is listed though, this would just be a stepping stone for more things to pick on once you start down this road.

Next thing that comes to mind is do you run these control(led) leads in a separate raceway or cable from the service conductors? Assuming it is essentially a switch loop through these two extra jaws - so that would make them non service conductors and they can't be in the same raceway/cable as the service conductors.

Next - even if they are permitted in same raceway, unless they are just signal wires they then would need to be counted as current carrying conductors for the purpose of ampacity adjustments.
These water heaters are rented from the POCO. I don't know if they modify them, most of them have a 4 sq j-box on the top with all the conductors. No 2nd meter as some posted. Also every one I've seen the wires were run in the conduit with the service conductors. This one has two 10-2 bx cables running to the heater from the panel, then one landed on the 30a breaker, the other skinned long and into the conduit to the meter off peak jaws. As I'm thinking about it it seems like just one leg of the 240 for the bottom element goes through the meter.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
These water heaters are rented from the POCO. I don't know if they modify them, most of them have a 4 sq j-box on the top with all the conductors. No 2nd meter as some posted. Also every one I've seen the wires were run in the conduit with the service conductors. This one has two 10-2 bx cables running to the heater from the panel, then one landed on the 30a breaker, the other skinned long and into the conduit to the meter off peak jaws. As I'm thinking about it it seems like just one leg of the 240 for the bottom element goes through the meter.

That's interesting,
I will add that I have seen many manufactures instructions for 4500W water heaters have a table that lists a 25A breaker @ 240V then of course a larger 30A breaker would be a violation of 110.3(B).
 

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Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
That's interesting,
I will add that I have seen many manufactures instructions for 4500W water heaters have a table that lists a 25A breaker @ 240V then of course a larger 30A breaker would be a violation of 110.3(B).


Does that say max overcurrent protective device? I am not sure that would limit the device to 25 amps.
 
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