Add 8 gauge wire in attic

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Old 04-03-20, 09:07 PM
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Add 8 gauge wire in attic

My task is to add some electric water heaters beneath the sinks for instant on hot water. One kitchen and 2 baths. We own and live in this house. The heater manufacturer declares that it uses 40 amps at 220 volts. Based on that I am using 8 gauge wire. We live in California.

My searches for an NEC site and the 334 code have been unsuccessful. What parts of the 334 I do find donít seem relevant to this situation. This leads to some questions.

1. Is there a place where the code can be found and downloaded.

2: I see things about always have a neutral wire. The heater has three wires, two hot and one ground. No neutral. Is that going to be a problem?

3: I have learned about the new Arc fault circuit interrupters (AFCIs). But this wiring will never have anything changed, plugged in, or unplugged. I presume that there is no need for an AFCI.

4: GFI, Ground Fault Interrupter. Those are expensive, about $100 for the 220 volt 40 amp. But could be well worth it. Problem is, they have a connection for White wire, line neutral. But there is no neutral on these water heaters. Just two hots and a ground. How does that work out?

5: Staples: In various conversations I heard that the wires need to be stapled down. None of the cables in our attic are stapled down.

6: Wire Nuts: 8 gauge is pretty stiff stuff. I purchased some screw down terminal strips rated at 40 amps and 600 volts. Will it be okay to put the strips in a plastic box under the sink? The strip will be screwed down to the box, in turn screwed down to a structural 2 x 4.

Jeez. This is too much to ask in a forum. If you want to just answer one question that will be appreciated.

Thanks for your time.
 
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Old 04-03-20, 09:35 PM
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The code is not posted in full online as it's purchased in book form. Excerpts can be found and quoted on many parts of the code. If you are looking for specific code references..... you need to start by finding out which year cycle your area is in. The code is rewritten every few years and towns and municipalities adopt a version.

Does that heater spec #8 wiring ? #8 NM-b is rated for 40A which means the wire will be operated in a continous mode near capacity. Is there a breaker size specified ?

Heaters like that require 240v only and no neutral. Therefore you can use 8-2 NM-b w/ground.
Unless specifically called for in the heater instructions.... AFI and GFI protection is not required.

With a device of this type you are required to install a service disconnect at the heater. It can be as simple as a 2P 60A A/C disconnect. Your supply wire goes directly to the disconnect and then to the heater. There won't be any other splices. There should be a place in the heater for the service wire to be connected. Usually it's a terminal strip with setscrews.

Cables need to be run and fastened in an out of the way location so that it can't be damaged.

How many of these things are you installing ?
If each one is 40A..... you'll need a 200A service minimum.

Example of service disconnect. Nothing fancy. 60A disconnect
 
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Old 04-03-20, 09:36 PM
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A straight 240 volt circuit does not need a neutral, just 2 hots and a ground.
Do the instructions call for gfi protection?
The connection should be made in the unit itself. Do you have 1 or 3 units?
 
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Old 04-04-20, 06:15 AM
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1. Is there a place where the code can be found and downloaded.
Yes, in the NFPA 70 NEC codebook. You can get it as a digital version for 1 year. You will also need to look in sections 300 and 310, not just the NM cable section. You might also need to look at section 422 Water Heaters.

2: I see things about always have a neutral wire. The heater has three wires, two hot and one ground. No neutral. Is that going to be a problem?
No.

3: I have learned about the new Arc fault circuit interrupters (AFCIs). But this wiring will never have anything changed, plugged in, or unplugged. I presume that there is no need for an AFCI.
The circuit for a water heater is not required to be AFCI protected.

4: GFI, Ground Fault Interrupter. Those are expensive, about $100 for the 220 volt 40 amp. But could be well worth it. Problem is, they have a connection for White wire, line neutral. But there is no neutral on these water heaters. Just two hots and a ground. How does that work out?
A GFCI would work just fine as the others have mentioned, but GFCI protection is not required for water heaters.

5: Staples: In various conversations I heard that the wires need to be stapled down. None of the cables in our attic are stapled down.
NM Cables are required to be secured/supported every 4 1/2'. Cables that are fished are not required to be secured.

6: Wire Nuts: 8 gauge is pretty stiff stuff. I purchased some screw down terminal strips rated at 40 amps and 600 volts. Will it be okay to put the strips in a plastic box under the sink?
I would not recommend using terminal strips. As the others have posted you need an A/C disconnect next to the water heater. The best way to do it is to feed the cable into the disconnect and then feed the water heater off the disconnect using some flexible conduit. The disconnect will have good quality terminals to connect the wires to.
 
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Old 04-04-20, 08:41 AM
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Wonderful answers. For Pete,

Often I do things out of order. Starting with the part about going direct to the heater I opened the heater and see that the wires in go to screw down terminals and can be easily replaced. Then I remembered the quick disconnect. I was unaware of that and will install one. But since the input power must be landed there I will use the supplied pigtail and not make any changes inside. Saw the Home Depot disconnect. The power can be landed directly there so I don’t need the separate screw down terminals.

And yes, we have 200 amp breaker panel for the house. We are installing three heaters. Two 40 amp devices for the bathrooms and one 30 for the kitchen sink. These have a temperature control so the temp is set and can never get too hot. Maybe not hot enough during the winter but probably good.

The cables will be up through the attics and down within the walls.

For pcboss: The instructions do not require GFI. Since it is a “water” heater it seemed like a good idea. I suppose I should skip that and use regular breakers. I will think on that. Maybe go the extra to be a bit more confident.

For Tolyn,

Again, Wow. Thank you for taking all that time.

Stapled ever 4 Ĺ feet. Ok, I have a box of staples and will try to be a bit less than that.

And the disconnect is the way to go. I will dispense with the screw down terminals.

And again, thanks to Pete, pcboss, and Ironhand.
 
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Old 04-04-20, 08:51 AM
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And this merits a separate response. The news is often filled with people behaving badly. But every time I visit forums like this there are really great answers and people have spent some of their time helping complete strangers.

I find that my spirits are lifted with each post.
Thank you again.
 
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Old 04-04-20, 12:09 PM
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I need two follow ups on the GFI circuit breaker. I just looked a maybe a dozen web sites and they all have the same breaker and same picture, exemplified here:
https://www.homedepot.com/p/Square-D...E&gclsrc=aw.ds

As I see the picture, there are three connections at the bottom. As 240 volts has two hots and a ground I "presume" that all three wires connect directly to the breaker. From the picture, the coiled white wire goes to the common ground within the breaker panel. Is that correct?

Second, are there multiple types of breaker panels? Is there only one "style" of circuit breaker that will fit all power panels. Or are there two or more configurations that are designed for panels by different manufacturers? I often say things wrong so to be redundantly clear: I refer to the part of the breaker that connects to the utilities supply power in the breaker panel. Is there more than one configuration?
 
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Old 04-04-20, 01:55 PM
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What your link shows is a 2P40A GFI circuit breaker for a Square D "Homeline" panel.
There are also Square D "QO" style panels.
Both made by Square D. Both use different breakers.
Most panels use different breakers. Most are not interchangeable.
Some manufacturers have different panels in their line and offer "universal" breakers.

A 240v GFI breaker is actually a 120/240v breaker. It will connect to both hot legs in the panel with a lead to neutral. If you use this breaker for 240v only..... there will be two load wires connected. Nothing will be in the neutral location.
 
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Old 04-04-20, 01:57 PM
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For the breaker itself the white pigtail connects to the neutral bar. If you have a 3 wire circuit then the circuit's neutral attaches to the breaker's 3rd lug. Since you are planning on 2 wire don't have to attach anything to that lug.

Breakers have to match the panel with few exceptions. On the panel's label will be a list of acceptable breaker types allowed.
 
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Old 04-04-20, 02:03 PM
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As I see the picture, there are three connections at the bottom. As 240 volts has two hots and a ground I "presume" that all three wires connect directly to the breaker. From the picture, the coiled white wire goes to the common ground within the breaker panel. Is that correct?
A 2-pole GFCI breaker has three terminals; 2 for hot wires and 1 for neutral IF the circuit has a neutral. This IS NOT a ground. In your case your heater's ground wire is connected to the ground bar in the disconnect and the neutral terminal on the breaker is not used. But you don't need a GFCI breaker.

Generally you are safe to match the brand of breaker to the panel. There is also a label in the panel that will tell you what breakers are approved to be installed in that panel.
 
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Old 04-04-20, 04:29 PM
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Regarding the circuit breaker types: My google searches are not phrased correctly and searches for types of breakers just brings up things like GFI and non-GFI breakers and nothing about the type with regards to how they plug in to the panel. One video showed the bottoms of the breakers, one with two metal feet to catch power and one with four metal feet. This panel uses breakers with two metal feet on one end. The panel is made by Square D. The label inside has a lot of information to include:

USE ONLY SQUARE D TYPES HOM, HOMP, HOMA OR HOMT BRANCH CIRCUIT BREAKERS. Looking at the breakers that all have HOM or HOMT printed on them. So when I order some 40 amp GFIs I need to be sure they are one of the HOM types or maybe HOMx.

Am I good there?

Regarding the wiring, and trying to summarize the last three replies. I will connect the two hots to the circuit breaker. I presume to the two outside screw downs, leaving the center one with no connection. The ground of the cable to the heater goes to the standard ground in the panel as does the white coiled wire in the image.

I looked at multiple sites and did not find any that show the ends and the bottoms of the connectors. That would have been helpful.

So, am I good on the wiring connections?
 
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Old 04-05-20, 10:30 AM
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USE ONLY SQUARE D TYPES HOM, HOMP, HOMA OR HOMT BRANCH CIRCUIT BREAKERS.
Your panel is a Square D homeline. That would be the correct breaker.

The wiring of the breaker sounds correct. However, I have had some GFCI breakers that trip if I connected the neutral pigtail to the neutral bus in the panel but didn't have any neutral wire connected to the breaker. You will have to see how your breakers behave after they are installed.
 
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Old 04-06-20, 06:32 AM
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Wonderful. I need to order some wire and breakers on line and during these times it may be a while before it is delivered. I don't know how long until I can make progress again.
Thank you for your time and patience.
 
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Old 04-06-20, 02:38 PM
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I need to order some wire
Many people use "wire" and "cable" intermixed. I just want to be clear, you need to use cable (an assembly of wires in an overall jacket) unless you are running conduit, then you can use wire. (Individual conductors)
 
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Old 04-10-20, 07:19 PM
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Yes, I should have written cable, not wire.
 
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