Water heater internally wired with 12 AWG wire instead of 10

[Fitzcarraldo]

The lower element is out on my 2005 model Whirlpool heater from Lowe's. I'm planning on replacing both top and bottom elements with 5500 watt stainless elements for the 20 percent decrease in recovery time. Supply circuit is 10 gauge Romex and the breaker is 30 amps. The issue: the internal wiring of the heater is 12 gauge (which of course doesn't even meet the 80 percent de-rating requirement for the OEM 4500 watt elements. Is this standard? I have indeed noticed wiring inside toasters and other electronics that is sometimes a smaller gauge than the current usage of that appliance would call for. Always assumed it had something to do with allowances for the single strand conductor just hanging out in free air or something of the like.

 

[hj]

5500 watt heaters come with #10 internal wiring.

 

[Sponsor]

 

[Jadnashua]

IF your WH was built for the optional higher powered elements, then you could swap. If not, then you cannot safely do it.

Supply wiring to the device is based on minimum voltage drop along the supply line...the manufacturer of the device determines what is a safe voltage drop of the internal wiring, and often, it is smaller than the supply line since they know how long it is and what they can live with to safely run their device...so, yes, it's not uncommon for the appliance to have smaller wire than required to supply it from the panel. This is similar to the lamp cord which might be as small as 18g, on a 20A circuit, which would require 12g feeding it at the wall. IOW, they do not have to match if tested and validated (in the USA, that's often UL approval) to work properly.

 

[Fitzcarraldo]

5500 watt heaters come with #10 internal wiring.

Yeah...I figured they did for sure. Also had figured 4500 watt heaters did too. After reading the two responses here, I took a look at my mom's slightly newer Whirlpool "smart" water heater with 4500 watt elements and it indeed has 10 gauge wire from the elements to the brain box up top. Possibly it had offered an option for 5500 watt elements from the factory in an upgraded model as jadnashua had mentioned. It's a 9 year tank warranty model, mine's a 6 year.....I've seen 9 and 12 year models with 5500 watt elements, but never a 6 year. I wonder if every low price point 6 year model coming out of Johnson City, TN (regardless of the nameplate) comes wired with 12 gauge?

I guess if I'm going to have to put the effort of pulling new 10 gauge wires thru the tank I might as well go all the way and rewire it for simultaneous operation with an ECO thermostat added to the bottom as well (and a second 30 amp branch circuit, of course). I've never had to have an expansion tank on any of the water heaters I've had in various houses, but I'm wondering if the extra speed of recovery from both elements burning at once will put just enough additional pressure on the T&P valve to make it weep while heating (I already run the thermostats maxed out to 150.....get about 145 at the tap).

 

[Reach4]

I would not worry about it. House wiring rules are different from the internal wiring design standards of appliances.

 

[Jadnashua]

An ET is only required if you have a closed system, or the local regulations call for one. The pressure will not build if it is an open system. But, if it is closed, and it doesn't pop the T&P valve, water is leaking somewhere, limiting its rise, or you have a lot of flexible piping or hoses, and those are ballooning (not great for longevity) - copper pipe won't balloon until you've got way more pressure than you'd be able to create in a home water system without something else failing first. The most common valve to leak is a toilet fill valve, and there'd be no overt indication of failure since the excess water would just go down the overflow and out the drain if it got that far. But, a leaking faucet somewhere could do the same thing.

 

[Fitzcarraldo]

Hard to say if I have a closed system or not. I indeed have a pressure reducer (plumbed it in myself in 1997).....however, it quit working in 2005 one day when I shut the water off and back on at the meter at the road to repair a leaking shower valve. Pressure was noticeably greater coming out of all my faucets from that day forward. I didn't worry about it because all the other pressure reducers in all of the other houses here on our family farm had been out for years as well (with no detrimental effects whatsoever). So even though I know my pressure reducer isn't working, I have no idea if the check valve portion of it would still be working and preventing backflow of water to the street or not. The water company replaced all meters with spiffy new Badger smart meters about 3 years ago, so likely a check valve at that point if indeed that's the new protocol for most. But I also have 420 feet of 1 inch PVC between the road and the house, which may or may not allow for some expansion room.

What do you think?

 

[Jadnashua]

Pick up a water pressure gauge, and check! They're not expensive. Get one with a second, peak reading hand (tattle-tale) so you know what both the instantaneous and peak values are. Leave it attached for at least 24-hours and see. Usually, the easiest one is one with a hose connector...attach it to a washing machine supply, the drain on the WH (caution, it will get hot!), or anywhere if you buy an appropriate adapter.

It will be telling to use a lot of hot water, then once that has stopped, watch the pressure while no other water is being used in the building. If you have a closed system, the pressure will rise while the WH is reheating the water unless there's a leak somewhere that relieves it.

If your average water pressure exceeds 80psi, code calls for adding a PRV, which will make your system closed while it is functioning properly. Note, some of them have a built-in relief valve, but that won't open until the building pressure exceeds the supply pressure. The goal is to keep the pressure steady, not let it surge and wane. That's where the expansion tank comes in...it gives the expanding water a place to go, then it gets expelled when you next use any water, ready to do it all over again (until it fails!).

 

[Fitzcarraldo]

I've had a water pressure gauge for probably over 20 years.....it's how I first figured out the pressure reducers weren't working in our other houses. However, it doesn't have a lazy hand on it, so I had to wait until the girlfriend went back home after the weekend (too much effort to get her to not touch the toilet or sinks for an hour and a half while the water heater went thru a full recovery cycle). First off, an amendment to my previous post.....turns out I do have a functioning PRV after all. I can likely trace that back to some work the water company did to our main line on our road about a year ago. After their work I noticed a slight pressure drop at all of our houses and at various frostproof hydrants spread around the farm.....just figured they had lowered the setting on their own PRV somewhere in their system. My house however had a steady rhythmic pulsing most noticeable at the faucets with aerators on them...not so noticeable in the shower or at the spigots. I figured it was air in the system from their work at the road.....there had indeed been a large initial surge of air and water when the water first came back on. I figured it would clear in short time, and it did, but it took a few weeks. I now wonder if that surging wasn't my PRV coming back to life after something akin to a de-fibrillating blast from the water main. Regardless, it now works. 60 psi is what it reads right after opening and closing a faucet. It tends to creep up to 65 psi if left to sit. Once it read 70, but I had run about a gallon of hot water thru the sink.....don't know if that cycled the water heater thermostat or not. Never saw it above 70psi though. Until I emptied all the hot water thru the bathtub, that is. Let it run until the temp dropped from 145 to 85 degrees. City water coming in right now is 55 degrees, so most of the hot had been exhausted. Calculated about 1.5 hours for full recovery (I have temporarily replaced my previously faulty lower element with
a good 4500 watt one, so things are working as they should with the water heater for now). After 30 minutes it was at 103 psi. At the one hour mark it was 105 psi. Same thing at 75 minutes. At an hour and a half the pressure had dropped to 90psi and the lower element had already shut off (verified with multimeter). Opened up a faucet for a few seconds on hot and cold and everything was back to 60psi and holding.

So...obviously a closed system, correct? Either at my PRV, or at the check valve at the meter 420 feet away. Is 105 psi during a recovery cycle generally considered too high? Incoming city pressure measured at the frostproof hydrant right after my city meter is 122 psi. Pressure at my brother's and my mom's is respectively 115 and 112, and that's INSIDE the houses...after the non-functioning PRVs. When I measured them 20 years ago when I first got the gauge, both their houses and the roadside hydrant at my meter were all reading over 130 psi. No damage has ever come of it.....one house was built in 1971...the other in 1982. Those two houses are copper pipe.....mine is CPVC (did I just admit I'm the blacksheep living in a house trailer at the other end of the farm...LOL). I know they say PVC will last a hundred years corrosion-wise, but is it inferior to copper and galvanized when it comes to handling high pressure? Or is the main concern of excess pressure one of fixtures and water heater tanks? Seats and springs are easy enough to replace...and we all seem to be getting about 15 years out of our water heaters. I wonder out of curiosity if the other two houses go up another 45 psi from 115 to 160 when the water heater is cycling. The non-working PRVs may not be preventing backflow to the street, but I'd say the recently installed meters do indeed. So they're both likely closed systems as well.

All this talk and I guess my two questions basically are:
1. Is 105 psi too ideally high for my CPVC pipes or my water heater?
2. Is the rhythmic surging I described earlier indicative of a PRV going bad (or in my case, going GOOD again)?

And while I'm at it, a third question. Considering the 45 psi spike I'm getting now with only a 40 gallon heater, there's no chance I'm going to be able to add a second 40 or maybe even a 50 gallon heater to the system and get away without adding an expansion tank as well, is there? As you mentioned light-heartedly at the end of your response ".......until it fails". We had a well on our other farm when I was a kid. I remember all too well having to climb down inside the well house every few months to pump up the waterlogged galvanized tank it had. I know bladder tanks are improvements over the old tanks, but it's still a weak link I'd rather not have in my system at all if it's not truly necessary.

 

[Jadnashua]

Plumbing code says 80psi or less in a home. Those spikes from water expansion should be absorbed by a functioning ET. Increased pressure puts stress on hoses and seals. Will it cause them to fail...possibly. Constant flexing can cause various materials to degrade just like if you bend a metal clothes hanger back and forth enough, it breaks - doesn't happen the first time. Since most pipe won't balloon much, it sounds like something in your house is leaking when the pressure rises. A common weak point is a toilet fill valve, and it won't show up as a leak. But, any leaking faucet could be enough to limit the pressure rise. Get everything tight, and you'll likely see that pressure rise high enough to cause your T&P valve on the WH to open.

 

[Fitzcarraldo]

I intentionally closed the angle stop on the toilet to avoid that variable. Made sure to carefully shut off the bathtub and sink valves as well (as one of the sinks does usually drip if not centered precisely...Delta). So I'd say this is as bad as the pressure is going to get under current conditions. And usually better; as I hardly ever shut that sink off perfectly, and the hot valve on the shower has plastic internals which tend to drip after a shower unless you come back and reseat it after things have cooled down. That never happens either. So I'll just view these as happy little annoyances that are keeping water expansion in check. I almost never use even the minimum 2000 gallons a month that I'm automatically charged for, so it's never been a concern. Based on your advice and my new findings though, if I do indeed decide to add a second heater I'll go ahead and plan on putting in an expansion tank at the same time. For now, I've decided to indeed put two 5500 watt elements in and wire them to run simultaneously and see if that gets me what I'm looking for. I'd just been making due with too little hot water for about a year, but now that I already have things apart to replace that lower element my interest in bettering things took hold. Thanks for your help.

 

[WoodenTent]

Inside of a device is not the same as your house. Your house is designed to NEC, the devices are not. NEC basically cuts the rating of wires in 1/2 for margin.

The devices are covered by basically the manufactures engineering, UL approval, etc. No real different than other parts your house is built out of. Things need to meet code, but they can also get there if they have Engineering Approval. Such as a PE signing off on it. Look at engineer lumber, roof trust, etc. This is how non-prescriptive construction materials/methods/designs get the go ahead.

Light fixtures often are only 16-18 gauge wire, appliances will be similar. Also just look at the supply to your house. The utility will use much smaller wires than what is on your side of the meter since the NEC doesn't cover there stuff.

 

[Fitzcarraldo]

Yep.....I remember how disappointed I was when the power company came and hung the overhead service line. All that good looking 2/0 cable I had run from the meter base to the breaker box inside.......then they turned around and hung 1 gauge from the transformer to the weatherhead.