Sub Panel

[vmtrob]

I have been asked by my employer to do some electrical work at his house. I have come across a problem with a sub panel he has. His house has one main panel and 2 sub panels. The one sub panel comes off the main panel from 2 44amp breakers. The problem is that these 2 44amp breakers also supply his furnace system. Now this work was not done by a licensed electrician and i am not a licensed residential electrician. The MAIN problem is that whenever he runs his TV, irrigation system (which both run from the sub panel) and his furnace the 2 44 amp breakers trip. Now obviously there is to much current draw on this breaker. My question is why would the previous electrician wire this sub panel and furnace on the same breaker? is this not dangerous?
( how can the breaker be rated to trip if the furnace draws to much current, when the sub panel is also running of this breaker. ie what if the sub panel is fully loaded and the furnace turns on, the breaker trips, but what if the sub panel is not loaded at all and the furnace is drawing to much current will the breaker trip? most likely not) I am not sure at this time what size breaker the furnace is suppose to have but will find out soon. Anyways i am just curious if this is violating any codes? i am pretty sure it does.

Rob

 

[petersonra]

I have never heard of a 44 amp breaker.

It is entirely possible that there is nothing wrong with the installation at all.

One possible reason for the breaker tripping might be the furnace blower motor could have an intermittent short.

I am curious how it would happen that he needs to run his irrigation system at the same time as his furnace.

Does your area require a special electrical license to work on residences?

 

[vmtrob]

From what i can remember the breaker was 44amps or something close to that. Yes it is required to have a license or work under someone who does.
I have my diploma in electronics engineering so i am pretty confident in my knowledge of the circuits just not of the codes. Anyways the furnace/air conditioner unit tripsthe breaker, and i am pretty sure it is not a short in the furnace/air unit becuase it only trips when the irrigation system air and tv are on.

 

[petersonra]

I guess I would be inclined to start by measuring the current in the various devices involved.

But, really, it might be best to call in a professional.

It sounds like you might have a bit of a mess there and any digging around in it is likely to expose more mess.

 

[infinity]

Since you posted this in the Safety Forum I will assume that your main concern is the safety of the installation that you've described. So for the sake of safety I would call in a professional who is experienced in troubleshooting. As others have mentioned you could be opening a big can of worms.

 

[JohnConnolly]

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""The problem is that these 2 44amp breakers also supply his furnace system""


No....the problem here is an unqualified worker attempting to be an electrician. Tell your boss to call an electrician.


Heh heh. My first post and I am already talking smack.

I see this crap almost every single day and I hate it. Unqualified people should stick to changing lamps.

 

[haskindm]

In over thirty years as an electrician, I have never seen a "44-amp" breaker. They may exist but are certainly not common. I do not see how a "sub-panel" could be fed from "2 44amp breakers". Are you talking about a double pole breaker? 2 single breakers in adjacent spaces? Is the circuit for the circuit fed from another breaker in the sub-panel or tapped directly off of the buss in the sub-panel? What is the total load on the feeder to the sub panel when all of this equipment is running? You really need to get someone with a clue about electrical wiring to determine what is going on here. An electronics engineer is not an electrician, just as an electrician is not an electronics engneer. Stop messing with stuff that you know nothing about before you or someone else gets hurt!

 

[vmtrob]

First - Yes it is a double pole breaker, i am not 100% sure that it was 44 amps, i just remember it was something close to that, it is prob not 44 thats number just sticks in my mind.
Second - To connoly i beleive i am more then able to do this job, my daily job is machine and CNC repair and working with high industrial voltage. I beleive that re-running a feed for a sub panel is less thought consuming then diagnosing and troubleshooting problematic CNC machinery and running power lines to these machine tools. The only doupts that i have in this situation is why the previous electrician went about doing things this way. Why would he run a sub panel and a furnace/air system off of the same breaker. I don't beleive this should be done and that itcould damage the furnace/air unit. I said it before and i willsay it again, how is the breaker supplying the sub panel and furnace/air unit suppose to trip if the furnace is drawing over full rated amps (which at this point in time i am unsure of, but i am sure the rated value of the air/furnace unit is under the nominal value of the breaker)but the sub panel is drawing minimal amps. ie the added amperage of the 2 combine is less then the value of the breaker.
Then at the other end of the spectrum the breaker for the furnace/air and sub panel trips when the air and various other appliances on the sub panel are in use. This is the problem the breaker tripping when the air and various appliances on the sub panel are turned on. I think if u thought about it for 2 seconds you will see my point and that is that this should not be run in this way. The sub panel should be run off of its own breaker off of the main panel and the furnace/air unit should also have its own dedicated breaker. Anyways i was just looking for some insite on whether or not this was against code (ie the furnace/air unit sharing a breaker with the sub panel) but i do appreciate the arrogant cocky replies (connoly). until next time keep up that attitude and it will only get you disrespect from your co-workers.

 

[busman]

Different Disciplines

Different Disciplines

so i am pretty confident in my knowledge of the circuits just not of the codes.

As one with a B.S. and M.S. in Electical Engineering and a Master Electricians License (obtained after 6 years apprenticeship and 2 years as a journeyman) I feel pretty confident to address this. When I started as an apprentice, I thought that being an engineer would be a big advantage. It turns out it only helped with slightly over 1/3 of the knowledge required. To explain, there are really three parts to being an electrician:

Electrical Theory - EE is well qualified for this.
Codes (NEC primarily) - EE only gives you experience at studying large amounts of material
Practical - Tools, Materials, Techniques, Judgement (picking the best option)

Bottom line - when I started, I thought that being an EE was most of the way to being an electrician. I now know much better and the volume of what I thought I knew and didn't is staggering. With 10 years electrician experience and 24 as EE, I am still learning everyday. If you don't know the code, how are you qualified to replace a feeder?

One man's opinion.

Mark

 

[mario]

should be an electrician doing this ...

should be an electrician doing this ...

first I think you should have an electrician experienced in Trouble shooting to check this out ...
second I'll ask .. you keep saying sub and furnace fed from same breaker .. are there two wires on the same breaker .. most are not approved for more than one feed wire at a time ... m

 

[muskiedog]

What makes you think that an electrician install ed the sub-panels

What makes you think that an electrician install ed the sub-panels

I have a cabin that has been wired by multiple home owners. I ultimately removed the extra sub panels, disconnects exctera. No grounds hooked up. The more you will dig the more you will find.

 

[realolman]

First - This is the problem the breaker tripping when the air and various appliances on the sub panel are turned on. I think if u thought about it for 2 seconds you will see my point and that is that this should not be run in this way. The sub panel should be run off of its own breaker off of the main panel and the furnace/air unit should also have its own dedicated breaker. .

It seems pretty obvious that something is wrong.

I think your saying that something was fed from two 44 a. breakers really set off a bunch of alarms .

Checking some nameplates and actual amperages should tell you what to do electrically. It is kind of surprising to me that you wouldn't have done that right away, before coming here. Seems to me that is the job.

If I was going to do what you are doing, I'd be studying the relevent sections of that code book. Don't you have access to a code book in the workplace you describe. You would be sizing the conduit, feeders, and branch circuits, starters, overloads, fuses etc. to the machinery according to code.

I work as an industrial mechanic. Although I feel I have a good grasp of electricity, I don't know enough about the residential stuff to do it for someone else: This circuit has to be fed from that AFCI... and that can't be within this far from the tub... People ask me about stuff, and I hate to give them advice, because I don't know the residential codes. They probably think I'm a jerk. ( maybe they're right, but not about this )

Finally, you're not insured. If you do do something, get it inspected with your boss listed as the electrician. If something went wrong, you wouldn't even have to BE wrong. You'd be sued to high heaven. Maybe your boss wouldn't want to, but his homeowners insurance company would sue their own mothers before eating a claim themselves.

Deciding what to NOT do is not necessarily a shortcoming.

 

[charlie b]

I am closing this thread, in accordance with the Forum?s rules. This Forum is intended to assist professional electricians, inspectors, engineers, and other members of the electrical industry in the performance of their job-related tasks. It may not be clearly stated in the Forum rules, but if you are not an electrician or an electrical contractor, then we are not permitted to help you perform your own electrical installation work.

Just so you don't feel that you are being treated unfairly, let me tell you that I am a licensed PE in 5 states, that I have both BS-EE and MS-EE degrees, and that I do not feel qualified to perform the work you are describing. I have already put the membership on notice that if they ever catch me asking ?how-to? questions related to work I wanted to perform on my own home, they have my permission to decline to give me that kind of help.

You are most welcome to participate in this Forum. You may well find it to be a great learning opportunity. But we cannot help you perform you own electrical work. It is just not safe for us to do so, because we don?t know how much you do know, and what questions you should be asking but haven?t asked yet.