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Discussion Starter #1
looking to upgrade my panel from a 100amp service, and checked out the wire to see what I could get away with. turns out the cable says:

KAISER KATHENE (UL) SPEC 400 AWG AL 500 VOLTS TYPE XHHW

so, a little googlefu returned that this may be 400kcmil wiring, which is rated up to.... 280amps?! that can't be right? did I miss something here?
 

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I can’t imagine that you have 400 kcmil wire connected to a 100 amp service....the lugs typically aren’t rated for that large of wire. I picture would really help a lot.
 

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Wire Size Calculator

There are a number of wire size calculator’s on google. It depends on the length of the run, how much voltage drop you can live with and if you are going to use copper or aluminum. Good luck. If you are gong to be welding off that feed I would go at least a size heavier in wire just because it helps keep the lights from dimming. If it is a long buried run I would double it. I should say I did double it. My shed has a 100amp service but I sized the wires for 200 just because I don’t want to do that again.
 

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you know what, after moving all the wires out of the way to get a good shot of the wire... a very faint "2" that was half rubbed off became visible next to the AWG. ? this project just got more expensive.. and I may have to repaint and re-drywall....
 

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Discussion Starter #6
Wire Size Calculator

There are a number of wire size calculator’s on google. It depends on the length of the run, how much voltage drop you can live with and if you are going to use copper or aluminum. Good luck. If you are gong to be welding off that feed I would go at least a size heavier in wire just because it helps keep the lights from dimming. If it is a long buried run I would double it. I should say I did double it. My shed has a 100amp service but I sized the wires for 200 just because I don’t want to do that again.
no tools on this drop, it's just a small cabin in the woods. the real upgrade is so that I can run a 24kw on demand water heater. the panel is located about 6 cable feet from the meter on the outside of the house, but it's tucked into a wall I just closed up about a year ago, getting this place habitable again
 

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you know what, after moving all the wires out of the way to get a good shot of the wire... a very faint "2" that was half rubbed off became visible next to the AWG. ? this project just got more expensive.. and I may have to repaint and re-drywall....
That size sounds better. Typically when I do a service change out the existing wires wouldn’t be long enough in the first place if they were the correct size. How long of wire run and type of service are you talking about? You would need to change the meter socket etc and bring the grounding and other parts of the system up to code in most cases too. Basically what I am getting at here is unless it is an unusually long run the wire cost isn’t that much different but each job is different.
 

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Discussion Starter #8
That size sounds better. Typically when I do a service change out the existing wires wouldn’t be long enough in the first place if they were the correct size. How long of wire run and type of service are you talking about? You would need to change the meter socket etc and bring the grounding and other parts of the system up to code in most cases too. Basically what I am getting at here is unless it is an unusually long run the wire cost isn’t that much different but each job is different.
the run is seriously only about 6 feet from the meter to the panel. i'll probably go to 200amp service, just to futureproof a bit, but honestly, I was just hoping I could've popped a 150a breaker into the panel if the wire was that over sized... lazy lazy! haha
 

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the run is seriously only about 6 feet from the meter to the panel. i'll probably go to 200amp service, just to futureproof a bit, but honestly, I was just hoping I could've popped a 150a breaker into the panel if the wire was that over sized... lazy lazy! haha
It is never a good idea to take shortcuts on an electrical panel. I have seen to many shortcuts taken over the years, that have cost current owners lots of money & risked the lives of lots of people.
 

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the run is seriously only about 6 feet from the meter to the panel. i'll probably go to 200amp service, just to futureproof a bit, but honestly, I was just hoping I could've popped a 150a breaker into the panel if the wire was that over sized... lazy lazy! haha
How far is the transformer from the service panel and what size wire did the power company use. It may have to be upsized also!
 

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In Michigan I believe you're responsible for the wire all the way to the top of the pole at the meter or if underground all the way to the top of the service pole. So if the wire to the panel from the meter isn't sized correctly the piece from the meter to the tie in at the top of the meter pole would also have to be changed. That's the way it was when I built my workshop (on a separate meter) and 30 years ago and when I changed my house to underground 20 years ago.
Ron
 

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Discussion Starter #12
It is never a good idea to take shortcuts on an electrical panel. I have seen to many shortcuts taken over the years, that have cost current owners lots of money & risked the lives of lots of people.
yep. that's why I was checking the wire size going into the box before doing anything.

as far as how far from the transformer I am... it's literally only 25-30 feet from the house, and this cabin is the only one served from this transformer. my choice now is to try to either upgrade the panel to 200amps, or figure out a way to safely vent a tankless propane heater that has to be on a wall where the walkway is...
 

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yep. that's why I was checking the wire size going into the box before doing anything.

as far as how far from the transformer I am... it's literally only 25-30 feet from the house, and this cabin is the only one served from this transformer. my choice now is to try to either upgrade the panel to 200amps, or figure out a way to safely vent a tankless propane heater that has to be on a wall where the walkway is...
We went tankless in the house a couple years ago. Granted this is in our house not a cabin. Do you have any experience with tankless systems and sizing them? I ask because I read a lot on them before we went that route. Let me start by saying we love it. A lot of people switch them them and hate it. There is some lets say adjustments to life with a tankless system vs a traditional tank heater. I would say a key bit of information needed is what is your water temp of cold water coming out of the ground in the winter? Also what is your flow rate (number of simultaneous points of use and GPM at each). A tankless system works off a delta. Meaning it can change the temp of the water so many degrees at a rate of so many gallons per minute. The lower the flow the higher change in temp. If you might run two showers or in our case one with a 1" feed to it because of all the heads plus a dishwasher and washing machine at the same time. So I needed to account for a lot of flow. Once I did the math on our house I came up with an electric system that would have used up to 3 x 40A 240V. So while it would have been great to not have to deal with venting, it also meant that my water heater would pull up to 120A plus another 30A for my well. Like you I was limited by the power coming into my hose which in my case is a 150A service. CRAP!!! I am going to be taking showers in the dark... It was cheaper and easier to figure out the venting and go with a 199,000 BTU/hr natural gas tankless system.

Where some people complain about tankless systems is that they are used to setting the temp for their shower the same way. Turn the hot on full and the cold on half. They jump in after swapping out heaters and wonder why they are taking a cold shower. With a tank system you heat the water much hotter than needed at the point of use and then cool the water by mixing in cold. In an ideal tankless system you only use hot water not cold and heat the water to lower temps. It is a waste to spend fuel or electricity to heat water only to turn around and mix it with cold. So when calculating that delta that I mentioned above you may only want to shoot for 125F or so based on input temp and the delta that it can apply at the flow rate that you need. We installed the tankless system at the same time as doing a main bath remodel where I went from the old style manual mixing valves to one where it has a degrees F dial. Dial it to 110F and turn it on. It handles mixing the water for you. The one other drawback is minimum flow. Just the other night I was shaving and turn the hot on pretty low. Well the flow wasn't quite high enough to meet the minimums and the tankless heater kicked out. It took a couple minutes for me to notice but all of a sudden I was shaving with cold water. This is more noticeable when trying to conserve water and run without the faucet wide open. More so when you are mixing in colder water because you don't want it at 125F. If you want warm water but not hot you may find you have to run it wide open.

A bit off your original topic but if you have any questions about a tankless system. Let me know. Again assuming you might be new to it.
 

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We went tankless in the house a couple years ago. Granted this is in our house not a cabin. Do you have any experience with tankless systems and sizing them? I ask because I read a lot on them before we went that route. Let me start by saying we love it. A lot of people switch them them and hate it. There is some lets say adjustments to life with a tankless system vs a traditional tank heater. I would say a key bit of information needed is what is your water temp of cold water coming out of the ground in the winter? Also what is your flow rate (number of simultaneous points of use and GPM at each). A tankless system works off a delta. Meaning it can change the temp of the water so many degrees at a rate of so many gallons per minute. The lower the flow the higher change in temp. If you might run two showers or in our case one with a 1" feed to it because of all the heads plus a dishwasher and washing machine at the same time. So I needed to account for a lot of flow. Once I did the math on our house I came up with an electric system that would have used up to 3 x 40A 240V. So while it would have been great to not have to deal with venting, it also meant that my water heater would pull up to 120A plus another 30A for my well. Like you I was limited by the power coming into my hose which in my case is a 150A service. CRAP!!! I am going to be taking showers in the dark... It was cheaper and easier to figure out the venting and go with a 199,000 BTU/hr natural gas tankless system.

Where some people complain about tankless systems is that they are used to setting the temp for their shower the same way. Turn the hot on full and the cold on half. They jump in after swapping out heaters and wonder why they are taking a cold shower. With a tank system you heat the water much hotter than needed at the point of use and then cool the water by mixing in cold. In an ideal tankless system you only use hot water not cold and heat the water to lower temps. It is a waste to spend fuel or electricity to heat water only to turn around and mix it with cold. So when calculating that delta that I mentioned above you may only want to shoot for 125F or so based on input temp and the delta that it can apply at the flow rate that you need. We installed the tankless system at the same time as doing a main bath remodel where I went from the old style manual mixing valves to one where it has a degrees F dial. Dial it to 110F and turn it on. It handles mixing the water for you. The one other drawback is minimum flow. Just the other night I was shaving and turn the hot on pretty low. Well the flow wasn't quite high enough to meet the minimums and the tankless heater kicked out. It took a couple minutes for me to notice but all of a sudden I was shaving with cold water. This is more noticeable when trying to conserve water and run without the faucet wide open. More so when you are mixing in colder water because you don't want it at 125F. If you want warm water but not hot you may find you have to run it wide open.

A bit off your original topic but if you have any questions about a tankless system. Let me know. Again assuming you might be new to it.
thanks for the advice. I've been looking into on demand heaters for a while, even got a quote to get a higher end rinnai installed by the nearest plumber, but they wanted thousands more than I thought was reasonable. Our groundwater is 42* on average, high 30's in the winter. I have one tub, bathroom sink, and kitchen sink. it's a small 70 sq ft A frame cabin, so it's not like i'm servicing multiple bathrooms, and I don't even have a dishwasher or washing machine here. my girlfriend and I are just sick of the 10 minute showers we are afforded with my tiny single element water heater, and I don't have space for anything larger. There's no NG service out here, since i'm pretty rural, so the choices are propane or electric. I don't like the propane because the location of the water heater would currently necessitate the exhaust of the unit exiting right out to where the walkway to get into the place is, and there's no easy way to get it vented anywhere else. the plumbers were going to run it up through a cupboard, and then out the roof, to vent their install. the only other option that my dad suggested was installing any heater in my crawl space, which i'm not sure if it's up to code for New York. the moisture down there worries me, so i'm avoiding that. otherwise, there's external water heaters, but we get sub-zero snaps almost annually, it seems, so I worry about one of those freezing up. so, if I go electric, I have no dependence on propane anymore. I can work on finding and installing sources of renewable electric like a wind turbine, and maybe some solar panels, and then figure out how to store said energy, as well.
 

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thanks for the advice. I've been looking into on demand heaters for a while, even got a quote to get a higher end rinnai installed by the nearest plumber, but they wanted thousands more than I thought was reasonable. Our groundwater is 42* on average, high 30's in the winter. I have one tub, bathroom sink, and kitchen sink. it's a small 70 sq ft A frame cabin, so it's not like i'm servicing multiple bathrooms, and I don't even have a dishwasher or washing machine here. my girlfriend and I are just sick of the 10 minute showers we are afforded with my tiny single element water heater, and I don't have space for anything larger. There's no NG service out here, since i'm pretty rural, so the choices are propane or electric. I don't like the propane because the location of the water heater would currently necessitate the exhaust of the unit exiting right out to where the walkway to get into the place is, and there's no easy way to get it vented anywhere else. the plumbers were going to run it up through a cupboard, and then out the roof, to vent their install. the only other option that my dad suggested was installing any heater in my crawl space, which i'm not sure if it's up to code for New York. the moisture down there worries me, so i'm avoiding that. otherwise, there's external water heaters, but we get sub-zero snaps almost annually, it seems, so I worry about one of those freezing up. so, if I go electric, I have no dependence on propane anymore. I can work on finding and installing sources of renewable electric like a wind turbine, and maybe some solar panels, and then figure out how to store said energy, as well.
The other nice thing about electric is you can move it closer to the point of use. Just throwing this out there but have you considered multiple, smaller units? As you kind of mentioned you don't have that many points of use. They make small under-cabinet units that are electric. That would take care of the bath and kitchen sink. I never really looked at them so I don't know the specs but I want to say they are 110v 30A or so. Since there is no tank they are pretty compact. I have seen these a lot over in Europe. Another benefit of them is you get hot water almost instantly since you don't have all that cold water in the pipes. This doesn't apply but if doing new installation you only need one water run. So you could save on pipes.

I am thinking something like this. This is the first one I found on Amazon. Not endorsing this product by any means. Just and example.
https://www.amazon.com/Atmor-Tankless-Electric-Including-AT-900-03/dp/B00LNICDKS

A similar unit could be used for the tub/shower as long as you were fine with limiting the flow. Might need a 240V unit if running a tub spout wide open. I just don't know the delta on the flow rating for the temps you are talking. I am in Minnesota and on a 160' private well on our property so our temps are pretty consistent year round at about 45F. Since it is just your Girlfriend and you at a cabin it likely isn't a big deal to say I am taking a bath or whatever and hold off on doing the dishes where the kitchen sink heater would pull more power. I get wanting to avoid propane. It can get expensive and agree venting can be a challenge. I really wanted to go electric but in my case I was in a similar boat where I was going to have to upgrade my service. That was going to cost way more than what going NG cost when factoring in venting and all that mess. I lucked out in that I had wall space on an exterior wall in my utility room in the basement which worked out well. I could go right out that wall it is fairly close to our deck but far enough away that it isn't an issue and far enough away from two windows to be fine as well.

The thing I found out on this project is that if you are thinking of going tankless, the time to do it is while your current water heater is working fine. If you try and do it when the water heater has failed you are better off just replacing with what you had and look into it again in a few years. you are likely not only looking at substantial water routing changes but possible venting and other issues. For instance I only had 1/2 copper gas line coming into my house. I had to upgrade everything to 1" black pipe. The replace the gas regulator and redo all the venting. Because the unit is much smaller, you want to move it as close to the point of use as possible. Along with that project I also ripped out 95% of the copper in my house and went to PEX all run back to a water distribution panel. Think of it like a circuit breaker for water. Each point of use hot and cold has its own run and can individually shut off from that distribution block. It was a lot of work but it is nice. If I ever have to work on anything it is easy to shut down that one line and not impact the entire house. At first my wife thought I was crazy that I wanted to replace all the copper. But then I pointed out the two bathrooms are right next to each other above the garage. We already had to open up the ceiling in the garage because we gutted the bathroom, made it bigger taking out an old closet and moved the toilet. The other other point of use that we had other than some water bibs was the kitchen. Well the kitchen is right above the utility room where we were installing the water heater and there is no finished ceiling in there so all the pipes were exposed. Only two of the water bibs had pipes run through finished ceilings so I just ran PEX to where I could and left them copper the rest of the way which is where the remaining 5% of the copper is still left in the house. We were already replacing a lot of it anyhow with the project so the kitchen was just two more runs as the dish washer is fed off the sink. Oh I also added a Reverse Osmosis system at the same time so that took care of the fridge.

Just something to consider. If you went with those smaller units, they may be a little more expensive than the single you are looking at now but cost savings would come from possibly not having to mess with the service coming into the house. Or if the only point of use that is causing an issue is the tub, a tankless for there for now and leave the old water heater there for the other points of use and deal with them later if that failed at some point down the road.
 

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Discussion Starter #16
I actually had to plumb the cabin from scratch, so it's already all pex. the water line comes in from the well to the pressure tank, up to a pex manifold that is directly behind the tub. there's maybe only 2 feet of pex from the manifolds, to the control valve for the tub. the bathroom sink is a bit further towards the western wall, and then the kitchen is about 10 feet to the east. like I said, small cabin. it was completely gutted when my family bought the property, and I've gotten it to where it is now. there's no propane in the house at all, at the moment. I just removed the propane heater after switching to a pellet stove to heat the entire place. i'd plumb that all myself, and have the propane company inspect and hook up the tank if we were to go that way. who knows. I've got a couple calls out to the only two electricians within 30 miles, one's coming next week to quote a service upgrade for me.
 

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Electrician here, but I'm not suppose to advise What size is your main breaker? How many spaces are in the panel? I'm assuming it's full.
So, if you need space in your panel, there are a couple options. A picture of your electrical panel would help.
One more question-are you planning on doing this electrical? Because, if you are, getting it inspected is probably a good idea.

P.s. If it's such a small place, you probably don't need an upgrade, unless you are planning for future expansion or something.


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Electrician here, but I'm not suppose to advise What size is your main breaker? How many spaces are in the panel? I'm assuming it's full.
So, if you need space in your panel, there are a couple options. A picture of your electrical panel would help.
One more question-are you planning on doing this electrical? Because, if you are, getting it inspected is probably a good idea.

P.s. If it's such a small place, you probably don't need an upgrade, unless you are planning for future expansion or something.


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100 amp service. potential water heater calls for 3 x 40a breakers, for a total 100a load according to the manufacturer. the panel itself is rated at 100a according to it's sticker. that right there tells me I need to upgrade. the panel has 7 open 3/4" breaker slots, though.

M2vELb3.jpg
 

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3-40amp breakers at 240v each? Whoa!! Your cabin sounded pretty small. Excuse me......but I must be missing something.

If I can help with something, I'll sure try.
If you replace your electrical panel, it's doubtful you will be replacing the wires from the meter to transformer.

I would advise you to pull the proper electrical permit (usually inexpensive), this way you can call the power company and let them know what you would like to do.

You can most likely use your existing meter box. Just a simple panel change. You WILL need to replace the main feeders from meter to panel. Is it less than 6' ? I'll go back to reread your posts.




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That looks like a main lug panel, or did your picture cut off the main breaker? If it’s a main lug, you should have a means of disconnect somewhere close by.

Also, no matter what you do, it looks like you have two exposed breaker slots so install two cover plates there. That’s very dangerous without a cover plate. Or you could put two breakers in those slots until you upgrade. Just mark them unused.
 
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