# Main lug only vs. Main breaker panels



## mikedl361

Ok I'm having a little bit of trouble understanding the difference between MLO panels and main breaker panels. Where would you use a Mlo panel vs a main breaker panel. Ive seen this topic on this site before but not getting a clear understanding about the Mlo panel. Any comments and answers would be appreciated. Thanks guys.


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## MikeFL

If you have a main at your meter I believe all you need is MLO for the MDP.
Another example is feeding a sub panel. Since you have a "main" for the subpanel at the branch in the MDP you need only MLO for the sub panel.


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## JRaef

MikeFL said:


> If you have a main at your meter I believe all you need is MLO for the MDP.
> Another example is feeding a sub panel. Since you have a "main" for the subpanel at the branch in the MDP you need only MLO for the sub panel.


It's not just the service main either, if you have a breaker in any panel that is feeding a sub panel, that sub panel CAN be MLO. If the sub panel is in another room though, I like having a main on it anyway because I don't like the idea of having to go into another room to kill power to a panel I'm going to work on.

Also, if your service or feeder is a Fused Disconnect, the panel down stream of it can be MLO.


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## Peter Goldwing

JRaef said:


> It's not just the service main either, if you have a breaker in any panel that is feeding a sub panel, that sub panel CAN be MLO. If the sub panel is in another room though, I like having a main on it anyway because I don't like the idea of having to go into another room to kill power to a panel I'm going to work on.
> 
> Also, if your service or feeder is a Fused Disconnect, the panel down stream of it can be MLO.


Are you serious saying you kill the power to work in a panel? Not that is not a good idea for the homeowner but i believe we're all contractors here.

When the subpanel is in a separate building if you have more than six breakers you need a main.


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## Signal1

Peter Goldwing said:


> Are you serious saying you kill the power to work in a panel? Not that is not a good idea for the homeowner but i believe we're all contractors here.
> 
> When the subpanel is in a separate building if you have more than six breakers you need a main.


We've all worked live, but good contractors know NFPA 70E, and know what lawsuits they may face by ignoring it.

It's not acceptable any more.


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## HackWork

Signal1 said:


> We've all worked live, but good contractors know NFPA 70E, and know what lawsuits they may face by ignoring it.
> 
> It's not acceptable any more.


70E clearly states that what JRaef proposed is just as dangerous and "wrong".

I really don't think it's fair to call a contractor good or not based on their adherence to stupid rules made by for-profit organizations who only have the purpose of making money in mind when writing those rules.


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## Signal1

HackWork said:


> *70E clearly states that what JRaef proposed is just as dangerous and "wrong".*
> 
> I really don't think it's fair to call a contractor good or not based on their adherence to stupid rules made by for-profit organizations who only have the purpose of making money in mind when writing those rules.


This is a true statement, as there are still energized parts, doing so without PPE would be wrong.

But this statement is what I disagree with:


> Are you serious saying you kill the power to work in a panel? Not that is not a good idea for the homeowner but i believe we're all contractors here.


So it's OK because your a contractor? In fact the way I see it it's the contractor that should know better, not the homeowner.

But I guess that's the key word-_"homeowner"._

When JRaef talks about working in a panel, I'm picturing a 550V distribution panel, while Goldwing is talking about a Homeline load center.

As far as NFPA 70E, like or not, it's there and we're expected to follow it, and when an electrical worker gets hurt the occupational hazard attorney is going to walk in, sit down, and pull a copy right out of his briefcase.


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## HackWork

Signal1 said:


> So it's OK because your a contractor?


 No, it's OK because you are an experienced professional and the task itself is less dangerous than driving to the job.

The rules are just making the way for less skilled and experienced workers.

Don't mind me, I'm just being a rebel today.


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## Peter Goldwing

Let me tell you this: in two occasions I drilled and tapped 3 live bus bars on a 800A service. We had to shut of Bradlees to do with no load. I let none do it but myself. I made 15K net in 5 days(20 years ago.) in one job while the other was part of the entire contract. Obviously you are a beginner and I would not recommend you do this. How would add a circuit in A Mc Donalds store?. Shut the power off in the middle of the night? You make me laugh. How you change a service? I cut the live wires and I resplice myself as REQUIRED by the power co. Yeah the code says.....
Are you checking your tire pressure every day as required for a commercial driver and the oil + the horn and and lights . Are you testing your homes GFIs monthly and the smoke detectors too? if you answer yes then financially you're not too far, wasting your time for meaningless crap. Yep the code says.......... and sometimes you need the power on to troubleshoot some circuits. You probably have high voltage gloves on, safety glasses and helmet


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## active1

As long as there is still exposed energized conductors in the main breaker lugs you sill need to suit up or LOTO down stream if you follow OSHA and 70E.

Not saying when of if you need to. Just that there is more to it than the buss is dead so the panel's safe. Unfortunately there have been cases where apprentices or helpers don't have a full understanding and get hurt.


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## Signal1

HackWork said:


> No, it's OK because you are an experienced professional and the task itself is less dangerous than driving to the job.
> 
> The rules are just making the way for less skilled and experienced workers.
> 
> Don't mind me, I'm just being a rebel today.


I totally get your point.

I can't even count how many 480V GE TE breakers I've bolted in live, among other things.
I would never do it today, it's not worth it.


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## Signal1

active1 said:


> As long as there is still exposed energized conductors in the main breaker lugs you sill need to suit up or LOTO down stream if you follow OSHA and 70E.
> 
> Not saying when of if you need to. Just that there is more to it than the buss is dead so the panel's safe. Unfortunately there have been cases where apprentices or helpers don't have a full understanding and get hurt.


100% agree.
This is what I said when Hack corrected me.


> This is a true statement, as there are still energized parts, doing so without PPE would be wrong.


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## HackWork

Signal1 said:


> I totally get your point.
> 
> I can't even count how many 480V GE TE breakers I've bolted in live, among other things.
> I would never do it today, it's not worth it.


I'm WAY too lazy to go shut something off just to have to go turn it back on again.


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## Signal1

HackWork said:


> I'm WAY too lazy to go shut something off just to have to go turn it back on again.


Now that you mention it, it does seem like a waste of time.


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## kg7879

Working energized for $35 an hour is totally worth it.


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## HackWork

kg7879 said:


> Working energized for $35 an hour is totally worth it.


I wouldn't pay you more than $20.


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## kg7879

HackWork said:


> I wouldn't pay you more than $20.


I would never work for a hack like you.


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## HackWork

kg7879 said:


> I would never work for a hack like you.


Bologna, you would love to work for me.




BTW, it's $15 now.


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## kg7879

HackWork said:


> Bologna, you would love to work for me.
> 
> 
> 
> 
> BTW, it's $15 now.


I probably would. Can we make it $22 though I got boat payments?


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## telsa

OP:

Keep in mind that its common for small MLO panels to be modified in the field -- such that they are back-fed through a two-pole breaker -- making that a Main C/B.

All that's required is a hold-down clip -- which are readily available -- to hold the push-on breaker firmly in place. ( A Code requirement in this instance. )


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## brian john

active1 said:


> As long as there is still exposed energized conductors in the main breaker lugs you sill need to suit up or *LOTO down stream if you follow OSHA and 70E.*
> 
> Not saying when of if you need to. Just that there is more to it than the buss is dead so the panel's safe. Unfortunately there have been cases where apprentices or helpers don't have a full understanding and get hurt.


UP stream,


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## brian john

I do not tell other electricians (besides employees) how or what to do with working energized. I will suggest what I feel is right, but they want to work hot it is on them not me.

I will say this DO NOT tell me it cannot go down. Bradless GIVE ME A F'ing BREAK.

If you screw up, it is going down.

We shut down hospitals, top government agencies, data centers, telephone companies if they can go down a shopping center sure as hell can go down.

Hotels are the worse and we shut them down.

Many cases we install temporary bypasses, allowing the load to be safely supported, the area to be worked on bypassed and off.

AS I have noted before on this forum.

I bet I have arranged more shutdowns of large facilities that could not go down than the average EC.

I have been on more investigations and cleanups than I care to recount where electricians were severely injured and a few where they died because the building owner could not shut down.

At a minimum place a piece of paper before the responsible party and have them sign it accepting ALL responsibility for loss of power and/or loss of life. You would be surprised how many find a time they can shut down.


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