Sub Panel on a 50A breaker? Legal?

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  #1  
Old 10-14-13, 04:36 AM
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Sub Panel on a 50A breaker? Legal?

Had an electrical contractor install a sub panel. The sub panel is served with a single 8 gauge wire, but there is a 50A breaker the subpanel. The subpanel has 4 8 gauge wires, each with a 50A breaker. The panel is located immediately next to the main panel. The four wires out of the panel serve 2 future tankless water heaters that require two 40A circuits a piece.

This just doesnt seem legit.
 
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  #2  
Old 10-14-13, 06:05 AM
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What you're describing is confusing to me. Can you take pictures of this installation?

Sounds like to me you need 160 amps for the water heaters.

Hope you have more than a 200 amp service
 
  #3  
Old 10-14-13, 06:36 AM
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The sub panel is served with a single 8 gauge wire, but there is a 50A breaker the subpanel. The subpanel has 4 8 gauge wires, each with a 50A breaker.
Your post is very confusing. When you say a single 8 gauge wire, do you mean a single 8 gauge cable such as 8-3 W/G NM cable or 8-2 W/G NM cable (aka romex)? Those #8 NM cables must be protected at no more than 40 amps.

The four wires out of the panel serve 2 future tankless water heaters that require two 40A circuits a piece.
From your description, I don't think you'll have enough power for one tankless water heater.
 
  #4  
Old 10-14-13, 06:50 AM
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The sub panel is served with a single 3 conductor 8 gauge cable from the main panel (it looks like 8/2 W/G, but I will open and verify), there is a 50A breaker on it. Currently, nothing is 'hooked up' so the sub panel is essentially not serving anything.

Inside the sub panel, there are 4 outgoing 8/3 cables, each on a 50A breaker. I have two 200A main panels. I am speaking about one 200A service panel that the subpanel is attached to. The main panel that the subpanel is attached to already serves lighting, outlets, a 5 ton ac unit and its air handler, a 2.5 ton ac unit and its air handler, 3 tankless electric water heaters, and the clothes drier might be on it too, I cannot remember.

Please let me know about the sub panel and how it SHOULD be wired, because I think its an unsafe setup and quite alarming considering its done by a licensed, insured and bonded, large operation electrical company in our area.

Right now, there is NO LOAD on the subpanel, because I have not hooked anything up. The immediate future will hold for sure will utilize two of those 8/3 40A circuits on the subpanel.
 

Last edited by agdodge4x4; 10-14-13 at 07:06 AM.
  #5  
Old 10-14-13, 07:10 AM
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The sub panel is served with a single 8/3 cable from the main panel, there is a 50A breaker on it.
The 8-3 cable should be on a 40 amp breaker, not a 50 amp.

Inside the sub panel, there are 4 outgoing 8/3 cables, each on a 50A breaker.
Each cable should be on a 40 amp breaker, not 50 amp.

The main panel that the subpanel is attached to already serves lighting, outlets, a 5 ton ac unit and its air handler, a 2.5 ton ac unit and its air handler, 3 tankless electric water heaters, and the clothes drier might be on it too, I cannot remember.
The capacity of that 200 amp panel would be at best borderline. You need to do a load calculation and to do that you'll need the actual wattage of the two new tankless water heaters you are wanting to add. You'll need a load calculation of that existing 200 amp panel load first and then with the two new heaters added to it, I think you'll come up short. My gut feeling is that the 200 amp panel is already maxxed out. Without doing a load calculation I can tell you the subpanel will not support two tankless water heaters as it is currently wired.
 
  #6  
Old 10-14-13, 07:23 AM
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If you have space in your panels to add these circuits, to me, the sub panel is useless.

If you need sub panels for extra space, I would think you would need a minimum 2-100 amp panels fed with a 80 or 90 amp breaker each.

One sub fed from 1 main and the other fed from the other main.
 
  #7  
Old 10-14-13, 07:42 AM
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I have two 200A main panels. One is used purely for 'heavy loads' and the other is 'everything else'. The one I am speaking of is the 'heavy load' one. But let's assume the main panel is big enough.

BTW, the only thing I would consider a 'continuous load' in this main panel is the AC. The water heaters are only running when water is being consumed, and they are not pulling 40A...that is just the electrical requirement in the manual. Also, The oven and fridges are on a separate panel.

If it was (hypothetically) would the subpanel fed with a 40A breaker on 8/2 W/G wire, and having 4 40A breakers in it be kosher?
 
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Old 10-14-13, 07:56 AM
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would the subpanel fed with a 40A breaker on 8/2 W/G wire, and having 4 40A breakers in it be kosher?
That would depend on expected load. Small tankless water heaters generally require one 60 amp feed. Obviously you can't feed a 60 amp load from a 40 amp breaker. Many whole house TWH requite two 60 amp feeds. Obviously a subpanel fed by a 40 amp breaker can't supply 120 amps. Are these very small point of use TWH? Even those are likely to require 30-35 amps and just one of those alone would max out a 40 amp feed.
 
  #9  
Old 10-14-13, 08:20 AM
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Yes, they are small. They would be considered "point of use". They feed single bathrooms, a kitchen, and a utility room. Two of them are dual 40A feeds, and one is a single 40A feed.

This subpanel, at most, will be utilizing two 40A feeds., possibly 3, but not likely.

Based on my manual, one of these feeds can be a 30A and the other will likely not need to be bigger than that according to the electrical guide in the manual for my water heater.

So, lets say there will be two 30A breakers in this subpanel.

I calculate this to be 48A MAX, at 80% load (208V). It should be well under that in reality. Since I am pretty sure it is OK to have a 50A breaker on an 8g wire with proper rating...shouldnt this setup be OK?
 

Last edited by agdodge4x4; 10-14-13 at 09:00 AM.
  #10  
Old 10-14-13, 10:00 AM
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So, lets say there will be two 30A breakers in this subpanel.
A 40 amp feed can't supply two 30 amp feeds simultaneous.

Since I am pretty sure it is OK to have a 50A breaker on an 8g wire with proper rating...shouldnt this setup be OK?
No. A 50 amp breaker must have a #6 wire. You must use the 60 column.

I calculate this to be 48A MAX, at 80% load (208V). It should be well under that in reality. While continuous load probably doesn't apply but even if it does it reduces the allowable amperage on a circuit not increase it.]
If you explained clearly to the electrician what you wanted you need to get another electrician and all the wiring needs to be replaced.
 
  #11  
Old 10-14-13, 10:16 AM
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OK, well, we won't be replacing 250 feet of 8 gauge wire. So....it will be 4 8-guage wires each on a 30A breaker in the sub panel. What is the appropriate wire size and breaker to feed the sub panel?

What if I reduce the subpanel to two 30A circuits, in that case, what is the wire size and breaker needed to supply the sub panel?

Im going to verify what wire exactly was used...Ill post back tonight with more details.
 

Last edited by agdodge4x4; 10-14-13 at 11:34 AM.
  #12  
Old 10-14-13, 04:16 PM
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OK. Here's what I really have:

Subpanel is wired with 8/3 + ground NM-B on a 50A breaker.

There are 4 breakers inside the panel also on 8/3 + ground, also each on 50A breakers.

In my 'wire pile' I have a lot of 6/3 + ground, type "MTW or THWN2 or THHN or TWN75"

So, how do I fix the sub panel? What I NEED from the subpanel is two circuits in it that will for sure be used at 40A each. I have another circuit in it that subpanel will POSSIBLY be used, and it can be a 30A. The other one circuit will likely never ever be used, so it can be deleted.

All of these are non-continuous loads.
 

Last edited by agdodge4x4; 10-14-13 at 04:47 PM.
  #13  
Old 10-14-13, 04:57 PM
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Subpanel is wired with 8/3 + ground NM-B on a 50A breaker.
Wrong. Should be a 40 amp breaker for #8.

here are 4 breakers inside the panel also on 8/3 + ground, also each on 50A breakers.
Wrong. The breakers should be 40 amp. The panel feed is unlikely to support four forty amp breakers.

That would be good for a 50 amp feed to the subpanel but it is unlikely a 50 amp feed will suport a panel with four 40 amp or four 50 amp breaker.

So, how do I fix the sub panel?
Start from scratch. You need a minimum of a one hundred amp feed using #2 wire connected to the lesser loaded of your two main subpanels.

Edit: Even the above may not be enough power for the new subpanel. Even worse earlier you wrote:
I have two 200A main panels. One is used purely for 'heavy loads'
but we don't know for sure if your service is 400 amps or if they double lugged a 200 amp service. If you have a 200 amp service this isn't going to work.
 

Last edited by ray2047; 10-14-13 at 06:52 PM.
  #14  
Old 10-14-13, 05:54 PM
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Please let me know about the sub panel and how it SHOULD be wired, because I think its an unsafe setup and quite alarming considering its done by a licensed, insured and bonded, large operation electrical company in our area.
If I were you, I'd be having a heart to heart talk with the owner of this company because nearly everything they have done is in violation of the NEC. As the owner, you should not have to be figuring out what needs to be done, that is the licensed contractor's job and they evidently don't know how. I hope they furnished you with their certificate of insurance before starting your job, you might need it.
 
  #15  
Old 10-14-13, 07:43 PM
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but we don't know for sure if your service is 400 amps or if they double lugged a 200 amp service. If you have a 200 amp service this isn't going to work.

OK...let's start here and work our way up. I have two panels. Both have 200 amp main disconnects. I have secondary 200 amp disconnects (one for each one) at the meter. I have two meters. One for each 200A panel.

Here is what is already on each panel. This has been seen by two licensed electricians, and a home inspector when I purchased the home. It has to date given no issues whatsoever with how it is wired nor has a breaker ever tripped in the 7 years Ive been here with 4 people.

Panel 1 setup:
15A x 9 breakers
20A x 17 breakers
20A dual pole Breaker
30 Amp Breaker

Panel 2 (where my subpanel is wired off of)

50A A/C Compressor (5 ton)
60A Air Handler (5 ton)
50A Compressor (2.5 ton)
30A Air Handler (2.5 ton)
50A water heater
50A Dryer
40A water heater
20A x 7 (general lights/outlets)
15A x 3 (general Lights/outlets)
50A Water Heater
40A Water Heater
30A Range

The two 40A water heater breakers go to ONE heater. A 50A goes to another, and a 50A to a third. The 50A heaters need an additional 40A to work properly while replacing the 50A breakers with 40A breakers. The wire is 8ga anyway.

Panel 1 is on a generator.

So, this is the setup. In the end...sub panel or not, i NEED two additional 40A circuits and an additional 30A circuit (I can deep 6 the 30A, if its too much). What to do? At this point, we are well outside the scope of the electrical work, so I will likely be doing it myself. I am comfortable around electricity and I kill everything before working on it.

I appreciate the help. I didnt create this, Im just trying to make sure its right and safe.
 

Last edited by agdodge4x4; 10-14-13 at 07:59 PM.
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Old 10-14-13, 07:58 PM
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Interesting..... I've never seen two full service meters at one residence.

You're showing a lot of power to the air handlers.... I'm assuming electric reheat coils.
Must be a massive dryer at 50amps. The norm is 30amps.

You're showing 30 spaces used in your main panel. What size is the panel/is the sub panel needed ?

If you're out of space your sub panel will need to be fed with a two pole 100amp breaker like Ray mentioned previously.
 

Last edited by PJmax; 10-14-13 at 08:16 PM. Reason: clarification
  #17  
Old 10-14-13, 08:09 PM
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Interesting..... I've never seen two meters at one residence.
The deal is that the owners had a handicapped daughter, and she was going to live on the second floor, with a full apartment, so she would pay her own bill with her own meter. Somewhere in there, that decision was changed....so I have two panels...one serves mostly downstairs lighting and outlets and is on a generator, and the second panel is for heavy loads that do not need to be on a generator.


Our dryer is a regular old cheap dryer. I have several double pole breakers that are 50-60A that are 'unused'....
 
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Old 10-14-13, 08:26 PM
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Pros, assuming this is used as a single residence isn't there a code issue with two separate power sources to the same dwelling?

Agdodge, you have a total mess. Forget the GC. You need to hire a licensed master electrician to sort this mess out. You may want to speak to an attorney if the GC isn't willing to give you a reduced price based on what you have to pay the electrician. Do not take any recommendation for an electrician from the GC nor let him hire one. You need an independent electrician.
 
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Old 10-15-13, 04:48 AM
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isn't there a code issue with two separate power sources to the same dwelling?
There's technically only 1 service split off to 2 meters.

This is where the 6 handle/throws rule applies.
 
  #20  
Old 10-15-13, 06:19 AM
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Agdodge, you have a total mess. Forget the GC. You need to hire a licensed master electrician to sort this mess out. You may want to speak to an attorney if the GC isn't willing to give you a reduced price based on what you have to pay the electrician. Do not take any recommendation for an electrician from the GC nor let him hire one. You need an independent electrician.

Read more: http://www.doityourself.com/forum/el...#ixzz2hnQs3mPl
Wait...what's the problem? We are off the subpanel issue for now. What's the problem with everything else? The GC and his electrician had nothing to do with this wiring.

This house was built and wired in 2001.

If there is really something wrong, I need more specifics. Sorry for sounding frustrated here, but I have had THREE certified, licensed, master electricians in this panel since I bought it and not one of them had a single issue or problem with it when I asked specifically about it being done right. On top of that, a home inspection by a well known anal inspector yielded no problems with the panels. So, im more than a little confused about what seems to be a problem with the existing panels.
 

Last edited by agdodge4x4; 10-15-13 at 06:58 AM.
  #21  
Old 10-15-13, 07:08 AM
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The title of the post is Sub Panel on a 50A breaker? Legal? It is not and the work is totally wrong and a subpanel that is NOT SAFELY supplied by at least 100 amps can't work. The main panel being used to supply the subpanel may not have the capacity to support a 100 amp subpanel. A load cac must be done. I would not trust anything these workers did anywhere in the house. They do not know how to do the work. Your question has been answered multiple times. If you don't understand what has been written I don't know how to make it clearer.
 
  #22  
Old 10-15-13, 07:19 AM
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Yes but we have ventured from the subpanel to my MAIN panel somehow and a post below indicated there was a problem. I did not realize your 'total mess' comment was specific to the subpanel. Sorry for misreading that.

I seriously value this information, no offense to you or other good professionals, but in my entire life, I have not to date had a contractor of ANY trade do everything 100% unless I caught it myself. Its a skilled trade industry problem, and thats just life. For every one of you guys, there is 1000 others that just 'get the job done'...thats what I have here...and its a craps shoot every time you call someone that is a licensed professional.

Here is my solution for the subpanel:

The three additional circuits will be removed from the subpanel and wired to panel #1 instead. It has a TON of power available and that will be legit. Since two of those 40A circuits are paired, I will move their counterpart from Panel #2 to panel #1 as well.

The sub panel will be wired to panel #1 using 6 guage wire and a 50A breaker or 4ga and a 60A. I will move a few 15A and/or 20A light/outlet circuits from Panel #2 to the subpanel (effectively adding them to panel #1). All I need to know is how many I can put in it. Perhaps 2 20A and 2 15A?

That will reduce the load in Panel #2, increase the load in Panel #1, and solve the subpanel issue and all associated code issues I believe.
 

Last edited by agdodge4x4; 10-15-13 at 07:50 AM.
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Old 10-15-13, 07:50 AM
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The three additional circuits will be removed from the subpanel and wired to panel #1 instead.
That should be okay.

the sub panel will be wired to panel #1 using 6 gauge wire and a 50A breaker or 4ga and a 60A.
#6 is good for 60 amps.

The number of 15 and 20 amp circuits in the new subpanel can best be determined by doing a load calc.
 
  #24  
Old 10-15-13, 08:02 AM
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Don't forget that panel #1 has a generator. A new load would likely require a new load calculation for the generator's capacity. Nothing is just "simple'.
 
  #25  
Old 10-15-13, 08:18 AM
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I will simply have to make a note about killing the water heaters before firing up the genset, but if I forget, and they pull too much, the breaker for the genset at 50A will trip safely.

The number of 15 and 20 amp circuits in the new subpanel can best be determined by doing a load calc.

Read more: http://www.doityourself.com/forum/el...#ixzz2hnuojT2n
Here's what I came up with: Lets overshoot and say there are 20 can lights, plus outlets. I used 2 small appliance loads, and my calculator forced a 'laundry' load, even though its not on the subpanel. I did not really factor in a TV and speakers though they will be plugged in. Knowing that much, I got a neutral demand of 44A.

Did I do it right?
 

Last edited by agdodge4x4; 10-15-13 at 08:36 AM.
  #26  
Old 10-15-13, 12:33 PM
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The manuals for my water heaters say that they use 17500VA, 14000VA, and 12000VA.
 

Last edited by agdodge4x4; 10-15-13 at 01:07 PM.
  #27  
Old 10-15-13, 09:07 PM
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I'm not sure I follow your 44amp neutral demand calculation. The idea is to have close to 0 on the neutral. 240 volt loads don't change the neutral current and 120 volt loads should be setup balanced across the two legs.

Quite a hefty heating load:
17500VA = 73 amps
14000VA = 59 amps
12000VA = 50 amps.
 
  #28  
Old 10-16-13, 05:57 AM
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My 44A neutral demand was in relation to ONLY lights and outlets on the subpanel....not the heaters. Was going to move those out.

That's what the manuals say, but the breaker and wire requirement for each of the heaters is 40A a piece. So...I have no idea how they came up with that. The 12000 requires a single 40A breaker and all the rest require dual 40A breakers. **shrug**

I guess at this point, Im trying to figure out a way to properly swap some things around between two 200A panels so it works right. obviously, these three heaters combined, and all running together with both the 5 ton AND 2.5 ton AC unit do not pull 200A because it has never tripped. But, I would like to move them around. Perhaps moving both AC to panel 1 would be enough while leaving all the heaters on panel two?

***I am currently waiting on a contact from the electrical company. Im going to set up a time for the owner or master electrician to see what his guys did.***
 

Last edited by agdodge4x4; 10-16-13 at 06:29 AM.
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