How do I protect a branch circuit - no panel access

[bczygan]

I've got a room in a building where one line of Romex comes in and from a junction box, it provides an outlet and a switched light. I want to extend the circuit and add a few fluorescent lights (4-4 bulb) and 6 additional duplex receptacles.
I don't have access to the panel and don't know the branch circuit size. I know it serves some other rooms as well. I want to protect my portion of the circuit. I will probably have to work hot to cut into the junction box and add a device or box. Might be able to pull a meter that serves it all.

I have some 14-2 for the lights and some 12-2 for the outlets.

What device can I use that will protect the whole thing and allow me to reset it if overloaded?

I know I have to assume 15A is the most capacity I have, or less, so I don't want to be popping a breaker somewhere that I can't get to.

 

[pattenp]

To do what you are asking is wrong in so many ways. You really need to know a lot more about the existing circuit before you can do anything with it. It sounds like you need an additional circuit.

Edit: I will add that if you add a small breaker panel for you part of the circuit after the junction box, the breaker panel you add can not have a main over current breaker larger than the breaker serving the circuit to the junction box. You will most likely need to use a small main lug panel and back feed a 15A or 20A single pole breaker as the disconnect.

 

[bczygan]

It is one of about 8 or 9 storage rooms. I don't know how many circuits serve them. Probably one or 2. I know I have to assume that they are 15A. I also know I could plug a fuse protected 15A plug in strip into the one outlet and then use an extension cord and lights with plugs. That would protect my portion of the circuit. Of course, others could overload the circuit and trip the breaker. I just want something mounted more permanently on the walls and ceiling so it is out of the way.
What is wrong with that? You mention that it is wrong on many levels. Can someone be specific?

 

[Dustball]

How about- you don't own it and you don't have permission to do it.

 

[bczygan]

How about- you don't own it and you don't have permission to do it.

I have permission. I need to know how to protect the part of the circuit I have regular access to. And should I use a GFCI?

 

[pattenp]

What is wrong is adding more load and extending the circuit without knowing the serving circuit size and overload protection. Plus working in a hot junction box without having access to the service panel. This just sounds like you are doing a tape and bubble gum work around instead of doing it properly. To me it sounds like a new circuit needs to be run to the room. I not trying to be an *** but it's hard to give good advice without knowing exactly what you are dealing with.

As I said before if it's a 125V 15A or 20A circuit, just add after the junction box a small main lug panel and back feed a 15A or 20A single pole breaker and go from there with your outlets and lights.

 

[bczygan]

The existing work is what is tape and bubble gum. The junction box is partly exposed to the weather and lacks a cover and all the connections in it are taped without wire nuts. That will need fixing. I will get the power cut to do the work. Is there any simpler device than a main lug panel that will do what I want?

 

[pattenp]

Can't get much simpler than this.

http://www.amazon.com/dp/B00002NB09/?tag=atomicindus08-20

 

[Speedy Petey]

You MUST Have access to the breakers that feed the wiring/devices/lights in your area.

What kind of messed up place is this? Unless this is your home that you live in you should NOT be doing this work, I DO NOT care who gave you permission.

 

[pattenp]

Something to be aware of is if the circuit for example is 20A and you add this panel and use a back fed 20A as the main breaker it's possible if you over load the circuit the breaker back in the primary main may trip before the new breaker trips. Which means you may be having to get access to the primary panel to reset the first breaker. All breakers aren't created equal so one may be more sensitive than another.

 

[bczygan]

Something to be aware of is if the circuit for example is 20A and you add this panel and use a back fed 20A as the main breaker it's possible if you over load the circuit the breaker back in the primary main may trip before the new breaker trips. Which means you may be having to get access to the primary panel to reset the first breaker. All breakers aren't created equal so one may be more sensitive than another.

Good point. If that breaker is 20A and I use a 15A it should avoid that problem as long as I am the only one putting a load on the circuit, but once anyone else uses the other 5 amps the same situation occurs. But that is true right now. If I use all the available amps and someone else adds to the load, we both get cut off with no way to reset...

And if the existing circuit is 15A, the situation you explain can happen too.

Would be nice to have a dedicated circuit with disconnecting means I have access to.

I'm thinking of making the whole thing portable. A box with a 15A breaker that will hang on the wall and plug in to the existing outlet. Run my outlets and lights from that.

 

[cyamaha2007]

You could get a a/c disconnect and wire out of that.

 

[mrb]

your addition is going to overload the existing circuit. 6 receptacles x 180va per = 1080va plus another what 600va for the new lighting? Dont make your proposed changes, run a new circuit.

 

[bczygan]

your addition is going to overload the existing circuit. 6 receptacles x 180va per = 1080va plus another what 600va for the new lighting? Dont make your proposed changes, run a new circuit.

Good point. You assume that I will have loads on all outlets. They are convenience outlets, located where needed but not loaded all the time. It's like a circuit in your home. You may have a number of outlets on a circuit but you don't load them all with 1400 watt loads. I will switch each light and use only 2 at a time max which equals 320 watts. Total load on the outlets at any one time will be 800 watts. Total would be 1120 watts. I know what the circuit will accommodate and won't exceed it. And if someone else does...well that's what breakers are for, right?

And speaking of breakers, which will trip the most quickly? I need that kind so my part of the circuit will trip first.

 

[Speedy Petey]

Good point. I will switch each light and use only 2 at a time max which equals 320 watts. Total load on the outlets at any one time will be 800 watts. Total wold be 1120 watts. I know what the circuit will accommodate and won't exceed it. And if someone else does...well that's what breakers are for, right?

Wow. Just wow.

 

[pattenp]

Just breathe deep... everything will be okay.

Wow. Just wow.

 

[ishiboo]

This sounds like either apartment garages or storage units. If you had permission, the owner would let you know how large the circuit was and more importantly SHUT IT OFF while you were making your wiring modifications... I call ********.

Do not modify the junction box hot, it is dangerous and likely against the law if you do not own the building. There are two ways to SAFELY do this:

1. Install a single or double breaker box ($15-20) and a single 10A breaker. This may be too large depending on what your neighbors are running, but 10A is the smallest breaker you can easily find. This box can have a flexible extension cord feeding it (cut the female end off, insert it into the breaker box with a proper strain relief and connect it), and any number of outlets, light switches, lights, etc. on the other end.

2. Do the same but instead of a breaker box, use a junction box with a fuse or circuit breaker. You can have a simple glass panel-mount fuse in the cover which are available anywhere in smaller ratings - 3A, 5A, 7A, etc.

 

[sberry]

Are you kidding? WTF. He is wanting to extend a boggered circuit, you figure he is likely to customise some overcurrent protection? Sometimes I really look to see just who responds to these threads and how. Got no concept of the question and who you are talking to, this thread is a brainfart at best right from the start. Guy got no business with tools, cant find his way back top a panel or fuse, cant run a new safe wire back to a panel.

A good thread was the water heater, could get a feel the guy was compentant to use a meter, he just missed the diag, good fix, this is a waste of time. Good threads reduce confusion in most cases not explore a way around a cobble job.

 

[ishiboo]

Are you kidding? WTF. He is wanting to extend a boggered circuit, you figure he is likely to customise some overcurrent protection? Sometimes I really look to see just who responds to these threads and how. Got no concept of the question and who you are talking to, this thread is a brainfart at best right from the start. Guy got no business with tools, cant find his way back top a panel or fuse, cant run a new safe wire back to a panel.

A good thread was the water heater, could get a feel the guy was compentant to use a meter, he just missed the diag, good fix, this is a waste of time. Good threads reduce confusion in most cases not explore a way around a cobble job.

Not sure what you're ranting on about... did you forget to take your pills today? Overcurrent protection was his original question/concern.

My suggestions were not a cobble job at all... doing it in either manner I suggested would prevent him from working on a hot circuit and provide the protection I asked for. Clearly he wants an additional breaker/fuse/etc. so that he if he blows it, he does not have to contact and wait for the building owner to reset the breaker that the OP does not have access to, so he can reset his instead.

 

[ishiboo]

BTW... I had this same setup in a storage unit. 20A circuit with one outlet, if the fuse blew it was at the owners convenience to reset it for me, all breakers were in a common location for the owner of course which allowed them to manage who got/didn't get power. (You paid for it)

 

[bczygan]

Ishiboo,
You understand this completely. I will do a combination of what you suggest with the plug to avoid working hot and the breaker to protect my part of the circuit. It's the best I can do right now. Old farm wiring is often like this. Minimal. Old house wiring too. My house isn't even grounded. I have to really watch what I plug in to each circuit avoid popping fuses in the 60A fuse panel. Houses built in the 40's weren't designed for microwaves and lots of electric and electronic devices or shops or window A/C or big stereos or especially the combination of all these.

Your solution works. It's better than running extension cords or plug strips all over. The breaker is only there to protect the circuit from me being stupid and overloading it. If I had control over the breaker or even if I was the only one on the circuit it would be easy. Thanks for the info.

 

[bczygan]

One last thing. The reason I want to put a breaker on a junction box is that I don't trust the fuses in the plug strips. Otherwise I would just plug one of those in and plug into that with wiring from the lighting and power circuits. Can you suggest a breaker that will mount in a junction box and take a feed from a cord and plug.

 

[mrb]

Good point. You assume that I will have loads on all outlets.

doesnt matter. if its commercial you have to consider 180va per receptacle. (then again this is an illegal bootleg job so i guess that doesnt matter)

 

[jeffmoss26]

This just screams dangerous.

 

[MrMark]

Oh I don't know. Ishiboo's solution seems plenty safe to me. He's just plugging in a custom power strip really. He just wants to have a local reset in case he trips a breaker. I actually think this is a very good thread. Too much drama on here sometimes.

 

['04 Cummins]

Oh I don't know. Ishiboo's solution seems plenty safe to me. He's just plugging in a custom power strip really. He just wants to have a local reset in case he trips a breaker. I actually think this is a very good thread. Too much drama on here sometimes.

What's to say he wouldn't trip the breaker back a the panel first? Trust me, it can/would happen, especially if the trip ratings are the same. I shorted a 50a circuit at work once, but guess which breaker tripped? Yep, the 400a main to that subpanel, not the 50... I predict Murphy's Law in this situation.

 

[MrMark]

He could VERY easily trip the main first. On a short circuit you are into the magnetic response of the breaker, and the magnetic response time on a dead short of any breaker regardless of current rating is essentially instantaneous. Thus, it would be a **** shoot on which would trip first. But, that is not what we are looking at here. I don't think he is wanting to make short circuits.

If it were just a small overload, like 20 amps on a 15 amp breaker back at the main panel, it would take quite a bit of time to trip based on the thermal response curve. Under this scenario, and this is the scenario the person is concerned with, his smaller breaker will trip first if the breakers are functioning according to their thermal curves.

Even if the main does trip then so what? He is in essentially the same boat he would have been without his custom strip.

 

['04 Cummins]

He could VERY easily trip the main first. On a short circuit you are into the magnetic response of the breaker, and the magnetic response time of any breaker regardless of current rating is essentially instantaneous. Thus, it would be a **** shoot on which would trip first. But, that is not what we are looking at here. I don't think he is wanting to make short circuits.

If it were just a small overload, like 20 amps on a 15 amp breaker back at the main panel, it would take quite a bit of time to trip based on the thermal response curve. Under this scenario, and this is the scenario the person is concerned with, his smaller breaker will trip first if the breakers are functioning according to their thermal curves.

Even if the main does trip then so what? He is in essentially the same boat he would have been without his custom strip.

If he running a 15a breaker, off of the panels 15a breaker, they theorically would trip at the same time. I'm not suggesting that its dangerous, only that it doesn't necessarily even help him at all...

Edit, I see pattenp already addressed this, somehow I missed it...

 

[MrMark]

If he running a 15a breaker, off of the panels 15a breaker, they theorically would trip at the same time. I'm not suggesting that its dangerous, only that it doesn't necessarily even help him at all...

True if the same manufacturer and type, but I think Ishiboo told him to get a 10 amp breaker, which should do the trick.

 

[ishiboo]

True if the same manufacturer and type, but I think Ishiboo told him to get a 10 amp breaker, which should do the trick.

Yes. You'd want both lower current and faster response protection on the "add-on" breaker. No guarantee an upstream breaker will not trip first in a dead short or something way over both breakers load capacity, but it should solve 99% of issues.

I'm assuming that if an upstream breaker trips, it's not a life-and-death situation... just inconvenient.

I agree - there is nothing unsafe electrically about this solution. Just some people who think code is the word of God and anything else will result in your instant death by electricity.