Main breaker in seperate enclosure

[mivey]

There are none that back this code proposal that I know of.

Doesn't surprise me. Of course when has lack of evidence ever stopped the NFPA?

 

[mbrooke]

No unprotected cable in structure and emergency response disconnect. Everything else is a convenience.

True, but not enough incidents have occurred to require such a sweeping mandate. As it he best way to cut power to a structure is to have the POCO cut the service drop.

 

[don_resqcapt19]

That's what I do. Unless working on the main and then we wait for POCO. I usually find something useful to do with my time. That is the way it is in my real world. Others can make their own reality.

The safety rules are important, and it just becomes that much harder to get compliance at locations where it is easy to follow the rules, when we have installations where compliance is not economically feasible. The new design makes compliance economically feasible when working in the enclosure that contains the service OCPD.

Of course that does not mean that everyone will comply even where it is easy to do.

 

[don_resqcapt19]

True, but not enough incidents have occurred to require such a sweeping mandate. As it he best way to cut power to a structure is to have the POCO cut the service drop.

Yes that is, but when you have utility response times that often approach an hour, even where there is a fire, that is not very helpful.

 

[mivey]

True, but not enough incidents have occurred to require such a sweeping mandate. As it he best way to cut power to a structure is to have the POCO cut the service drop.

For a simple service drop that may be true. Many utilities have a service crew that can be there in short order, especially if planned.

 

[mivey]

Yes that is, but when you have utility response times that often approach an hour, even where there is a fire, that is not very helpful.

Agreed.

 

[mbrooke]

Yes that is, but when you have utility response times that often approach an hour, even where there is a fire, that is not very helpful.

Pull the meter... ok that can have consequences. I do agree a disconnect here would be optimal.

 

[growler]

As it is the best way to cut power to a structure is to have the POCO cut the service drop.

You think the power company is the best way to cut power?

What if your dryer is smokeing tonight and your wife calls the Fire Department. The dryer is in the basement with the main panel and the room is full of smoke. They have some options, they can disconnect power by opening a disconnect, pulling the meter or calling the utility company.

Option NO. 1...Opening the disconnect. Take about 5 seconds and they find the dryer vent duct is clogged and smoking and they pull the dryer and put out smoldering lent. No problem and house is not harmed. Most fires are actually more smoke than fire to start with.

Option NO. 2...pulling the meter. Takes a little longer but still fast enough. They get the fire out with no problem. Now you have had your meter pulled and need a re-seal. The power company is not going to just seal this meter because you have had a fire and now you need an electrician and permit to check things out before meter can be replaced and power turned on.
In the City of Atlanta the minimum permit fee would be $200 plus the cost of electrical service call even if everything is perfect. You are going to spend at least $500 getting power truned back on plus the fact of going without power for a day or two. Bet you wish you had that disconnect now.

Option NO. 3... utility cutting power. Utility can't get there for 30 minutes so Fire Fighers pull the meter and we are back to option #2.

 

[kwired]

Option NO. 2...pulling the meter. Takes a little longer but still fast enough. They get the fire out with no problem. Now you have had your meter pulled and need a re-seal. The power company is not going to just seal this meter because you have had a fire and now you need an electrician and permit to check things out before meter can be replaced and power turned on.
In the City of Atlanta the minimum permit fee would be $200 plus the cost of electrical service call even if everything is perfect. You are going to spend at least $500 getting power truned back on plus the fact of going without power for a day or two. Bet you wish you had that disconnect now.

Still a design issue, if you want to protect from incidents like this put the outside disconnect in.

Some fire dept's may pull meter even if there is a disconnect right next to it.

Couple other things that have not been mentioned

On site generation - which is similar problem now as it would be if service disconnect were required outside - if you turn off utility power there still could be automatic transfer of a standby system.

Fire pumps - we almost always don't want those to get turned off in an emergency situation.

 

[iwire]

The shield cover has nothing to do with arc flash mitigation. It for protection against accidental shock hazards.

It prevents an acrflash from happening by keeping say those bare EGCs from NM from hitting the unprotected service conductors / lugs.

 

[don_resqcapt19]

You think the power company is the best way to cut power?

What if your dryer is smokeing tonight and your wife calls the Fire Department. The dryer is in the basement with the main panel and the room is full of smoke. They have some options, they can disconnect power by opening a disconnect, pulling the meter or calling the utility company.

They have the training and equipment to let them enter the smoke filled basement and would disconnect the power at the basement panel. If there is any evidence of an actual fire, they would be taking an attack line in with them. If no evidence of an actual fire, they would likely just take the thermal camera and an extinguisher in with them.

Option NO. 1...Opening the disconnect. Take about 5 seconds and they find the dryer vent duct is clogged and smoking and they pull the dryer and put out smoldering lent. No problem and house is not harmed. Most fires are actually more smoke than fire to start with.

Yes, much quicker than finding the panel in a smoke filled basement that they have never been in before.

Option NO. 2...pulling the meter. Takes a little longer but still fast enough. They get the fire out with no problem. Now you have had your meter pulled and need a re-seal. The power company is not going to just seal this meter because you have had a fire and now you need an electrician and permit to check things out before meter can be replaced and power turned on.
In the City of Atlanta the minimum permit fee would be $200 plus the cost of electrical service call even if everything is perfect. You are going to spend at least $500 getting power truned back on plus the fact of going without power for a day or two. Bet you wish you had that disconnect now.

Pulling a meter is not an option for many fire fighters as their department safety rules absolutely forbid them to do that.
It is actually fairly safe to put a water stream on energized electrical equipment at dwelling unit voltages. The stream is not really solid enough to conductor a hazardous amount of current back to the fire fighter. However the standing water on the floor or the ground is conductive enough and becomes a shock hazard if the standing water becomes energized.

Option NO. 3... utility cutting power. Utility can't get there for 30 minutes so Fire Fighers pull the meter and we are back to option #2.

In most cases they will fight the fire while the power is still on, but use more defensive tactics. This would not be the case for an active electrical fire. A fire in the electrical equipment would not likely be fought until the power is off.

 

[iwire]

That may be the case starting on 1/1/2020 for dwelling units. There is a requirement in the 2017 code that will become effective 1/1/2020 requiring an outside service disconnect.

I will be very surprised if MA and RI do not amend that out.

Very few services here have outside disconnects and I doubt local code officials will be in any hurry to change that.

 

[kwired]

How many high rise buildings have the service disconnect on exterior of building? Would you want them there? Even with a remote operator?

I don't think that many FD's automatically disconnect power until they know more about what is going on. The example of dryer vent smoldering would normally be determined to be limited to the dryer vent and in most instances power never would have been disconnected. Once it is determined the structure is on fire then they will have more interest in turning off power.

 

[iwire]

How many high rise buildings have the service disconnect on exterior of building? Would you want them there? Even with a remote operator?

We have done a few large supermarkets with external service disconnects but they are locked on and some also fenced in.

 

[growler]

They have the training and equipment to let them enter the smoke filled basement and would disconnect the power at the basement panel. If there is any evidence of an actual fire, they would be taking an attack line in with them. If no evidence of an actual fire, they would likely just take the thermal camera and an extinguisher in with them.

It is actually fairly safe to put a water stream on energized electrical equipment at dwelling unit voltages. The stream is not really solid enough to conductor a hazardous amount of current back to the fire fighter. However the standing water on the floor or the ground is conductive enough and becomes a shock hazard if the standing water becomes energized.

Don I never thought that Fire Fighters are afraid to spray water on energized electrical but they do tend to be Ax happy types and tend to open walls and ceilings the quick way.

If there is no disconnect there is a chance of hitting SE cable with no overcurrent protection. Even if they just hit the neutral and a phase they may do more damage than the fire.

 

[growler]

Very few services here have outside disconnects and I doubt local code officials will be in any hurry to change that.

We have disconnects outside all over the place and no problems at all. Some feel the need for a lock but that their option.

 

[growler]

How many high rise buildings have the service disconnect on exterior of building? Would you want them there? Even with a remote operator?

You can't compare a highrise to a house. Power is normally from an underground vault (transformer ) they have a sprinkler system and pumping station. If you were to cut power you would do more harm than good.

 

[growler]

I don't think that many FD's automatically disconnect power until they know more about what is going on. The example of dryer vent smoldering would normally be determined to be limited to the dryer vent and in most instances power never would have been disconnected. Once it is determined the structure is on fire then they will have more interest in turning off power.

I don't know why you would say that. The vent is normally near the dryer receptacle and once they hack around the vent or figure the receptacle may have gotten hot they will disconnect power. They do not make determinations as to the damage of electrical systems.

I have seen the power shut off and building condemned because of a small fire on the back porch. One wire got smoked ( outside receptacle). The FD figured the panel in the kitchen wall may have gotten hot.

The fire department puts out fires they do not make determinations as far as future safety are concerned. Even with a disconnect they may have your meter pulled.

 

[kwired]

You can't compare a highrise to a house. Power is normally from an underground vault (transformer ) they have a sprinkler system and pumping station. If you were to cut power you would do more harm than good.

I know, question becomes is this possible requirement going to be for dwellings only or a general requirement for everything? Most of art 230 is general and applies to everything.

Also will it be extended to the main disconnect for buildings supplied by feeders or just for service disconnecting means?

Now place service disconnect outdoors but in a locked fenced in area - have we accomplished much on this one?

 

[ggunn]

Don I never thought that Fire Fighters are afraid to spray water on energized electrical but they do tend to be Ax happy types and tend to open walls and ceilings the quick way.

When I was a kid the house next door had a small fire in an exterior utility room and the FD was called. My dad was standing nearby when a firefighter ran up to the utility room door wielding an axe. My dad told him "Wait!" and opened the door for him.