MLO Panel fed by breaker plugged into it

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jt700

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Waltham,MA
I've been asked to replace a small exterior meter socket and house panel in a condo complex. The meter socket and panel are connected by an offset nipple.


The meter socket is a 100 amp underground socket. The existing panel is a 8 circuit MLO NEMA 3R panel which is fed with a 100 AMP Breaker which is plugged into it (As a result there are 6 Remaining slots). The lugs are not in use.


Is it code compliant to feed the panel in that manner?
 
jt700 said:
..Is it code compliant to feed the panel in that manner?
Click to expand...

1) If not prominently listed or labeled as suitable for service equipment, the default for MLO is not rated for service equip..

If not service-Equip. rated, would never pass inspection, its a fire hazard, voids property insurance policy, must be ripped out.

2) Regardless of service equipment, any backfed main breakers also require hold-down kits, listed for the equipment.
 
ramsy said:
1) If not prominently listed or labeled as suitable for service equipment, the default for MLO is not rated for service equip..

If not service-Equip. rated, would never pass inspection, its a fire hazard, voids property insurance policy, must be ripped out.

2) Regardless of service equipment, any backfed main breakers also require hold-down kits, listed for the equipment.
Click to expand...


Any plug in backfed breakers require a hold down kit.
 
I believe I could alleviate the issue either two ways:


1. Install a 100Amp meter socket with a main breaker, then nipple over to a NEMA 3R MLO panel




2. Install a regular 100 Meter Socket, and install a NEMA 3R 100amp Main breaker panel




Do you agree either way would work?
 
jt700 said:
I believe I could alleviate the issue either two ways:


1. Install a 100Amp meter socket with a main breaker, then nipple over to a NEMA 3R MLO panel




2. Install a regular 100 Meter Socket, and install a NEMA 3R 100amp Main breaker panel




Do you agree either way would work?
Click to expand...

How do you know the panel is a MLO?
Some panels, mostly 100A, have the main in the 1st slot(s) on the bus.

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jt700 said:
I believe I could alleviate the issue either two ways:


1. Install a 100Amp meter socket with a main breaker, then nipple over to a NEMA 3R MLO panel

2. Install a regular 100 Meter Socket, and install a NEMA 3R 100amp Main breaker panel

Do you agree either way would work?
Click to expand...

Either of those could work but another option might be to read the label on the existing panel and see if it lists a position for a backfed main breaker and a hold-down kit to use.
 
jt700 said:
I believe I could alleviate the issue either two ways:


1. Install a 100Amp meter socket with a main breaker, then nipple over to a NEMA 3R MLO panel




2. Install a regular 100 Meter Socket, and install a NEMA 3R 100amp Main breaker panel




Do you agree either way would work?
Click to expand...

Either would work. So would a back fed breaker with a hold down clamp, which is pretty much what you have already.
 
jt700 said:
I've been asked to replace a small exterior meter socket and house panel in a condo complex. The meter socket and panel are connected by an offset nipple.


The meter socket is a 100 amp underground socket. The existing panel is a 8 circuit MLO NEMA 3R panel which is fed with a 100 AMP Breaker which is plugged into it (As a result there are 6 Remaining slots). The lugs are not in use.


Is it code compliant to feed the panel in that manner?
Click to expand...

The original may have been compliant at the time if it is suitable for service equipment

If you are going to replace , what difference does it make what you replace with as long as code compliant.

ramsy said:
1) If not prominently listed or labeled as suitable for service equipment, the default for MLO is not rated for service equip..

If not service-Equip. rated, would never pass inspection, its a fire hazard, voids property insurance policy, must be ripped out.

2) Regardless of service equipment, any backfed main breakers also require hold-down kits, listed for the equipment.
Click to expand...

Hold down is a more recent code. May have been acceptable years ago.

jaggedben said:
Either of those could work but another option might be to read the label on the existing panel and see if it lists a position for a backfed main breaker and a hold-down kit to use.
Click to expand...

The panel is going to be replaced. We don't know why though , in any case a hold down may not have been required.
 
I was able to check the meter socket today, there is no other conductors out the back.


This 100 amp service (House panel) is attached to the exterior side of a condo unit which has its own 200 amp service. It appears that the grounding conductor for the house panel enters the adjacent condo unit and hits the water pipe of the condo unit. Currently, this is the only grounding means for the house panel.

I was going to drive new ground rods when I replace the house panel service, but do I have to hit that water pipe in the condo unit again as well? The existing grounding conductor will be too short to reconnect, I wasn't sure if I even had to run a new one. Is it even legal to hit that condo unit's water pipe?
 
jt700 said:
I've been asked to replace a small exterior meter socket and house panel in a condo complex. The meter socket and panel are connected by an offset nipple.


The meter socket is a 100 amp underground socket. The existing panel is a 8 circuit MLO NEMA 3R panel which is fed with a 100 AMP Breaker which is plugged into it (As a result there are 6 Remaining slots). The lugs are not in use.


Is it code compliant to feed the panel in that manner?
Click to expand...

If I understand correctly what you are describing (an MLO panel "side fed" by a tied down backfed load breaker), it's something I see occasionally but not that often.
 
jt700 said:
I was going to drive new ground rods when I replace the house panel service, but do I have to hit that water pipe in the condo unit again as well? The existing grounding conductor will be too short to reconnect, I wasn't sure if I even had to run a new one. Is it even legal to hit that condo unit's water pipe?
Click to expand...

Yes, you need a Grounding Electrode Conductor to the water pipe. You can extend the existing one.
 
I'd replace with a meter/main/loadcenter (all in one), after figuring out whether this service is even allowed at this location - apparently is not the only service to the building though it doesn't supply any load inside.
 
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