Got the NEW 2011 NEC

[acrwc10]

Can you explain why it is a 'good' change?

Can you show any substantiation for this change other than your personal feelings?

I went looking and I cannot find any.

Here is the proposal that lead to the change


Maybe some one can tell me how this "NFPA 99: 4.4.2.2.1.1" became this "The branch circuit serving patient bed locations shall not be part of a multi-wire branch circuit." and what the reason was?

I suspect it is because we now have to handle tie MWBCs to protect us from ourselves. :roll:

I suspect it is the foot in the door to making ALL MWBC's needing handle ties in the next code cycle. The same way AFCI's were first required only in bedroom receptacles, now they are 2/3rds of the house.

 

[iwire]

I suspect it is the foot in the door to making ALL MWBC's needing handle ties in the next code cycle.

That is already required under the 2008 NEC.

 

[brother]

Can you explain why it is a 'good' change?

Can you show any substantiation for this change other than your personal feelings?

I went looking and I cannot find any.

Here is the proposal that lead to the change


Maybe some one can tell me how this "NFPA 99: 4.4.2.2.1.1" became this "The branch circuit serving patient bed locations shall not be part of a multi-wire branch circuit." and what the reason was?

I suspect it is because we now have to handle tie MWBCs to protect us from ourselves. :roll:

I cannot find the proposal online either, I can only tell you what I was told. Basically, in part is because some people were getting hurt off the shared neutrals, and in a hospital setting this was damaging critical life safety equipment (120 circuit became a 208 ) as well ie dialysis machines sometimes when that cycle machine is started it has to finish or else the person can have a blood clot and die. Also as you may have guess it, They like the limit the reason for turning off the circuits that do not need to be turned off especially at a hospital bed, since with the handle tie you have to turn off both of them.

In hospitals, even though the gerneral rule is to not have to do maintenance/repair with a patient in the room, at times this is not practical and one has to go in and do the change or repair on the outlets. This way a maintenance guy has a better chance of turning off the circuits he's working on and still leave some power on for the patient. Not to mentioned the required Preventive maintance that has to be done on receptacles that the Joint Commission requires from NFPA 99, in part for the Hospitals to get their 'certification'.

 

[gndrod]

A good reason

A good reason

I cannot find the proposal online either, I can only tell you what I was told. Basically, in part is because some people were getting hurt off the shared neutrals, and in a hospital setting this was damaging critical life safety equipment (120 circuit became a 208 ) as well ie dialysis machines sometimes when that cycle machine is started it has to finish or else the person can have a blood clot and die. Also as you may have guess it, They like the limit the reason for turning off the circuits that do not need to be turned off especially at a hospital bed, since with the handle tie you have to turn off both of them.

In hospitals, even though the gerneral rule is to not have to do maintenance/repair with a patient in the room, at times this is not practical and one has to go in and do the change or repair on the outlets. This way a maintenance guy has a better chance of turning off the circuits he's working on and still leave some power on for the patient. Not to mentioned the required Preventive maintance that has to be done on receptacles that the Joint Commission requires from NFPA 99, in part for the Hospitals to get their 'certification'.

Brother,
Great explanation that demonstrates where MWBC's are not used including NFPA Life-Safety 101 for home care centers. I might add, in the computer industry where there are other PLC (X10) circuitry mixed in also has coupling problems with wiring in MWBC's. Advanced remote control systems are more common now even in residential branch circuits that require extra coupling isolation in bus phase separation due to MWBC's.

The main reason of the NEC is for safety that has yet to cover concerns mentioned above to eliminate hazards. Using MWBC's comes with it's own surprises...like throwing a DP to fix a faulted circuit and at the same time cutting power to other critical circuits.

 

[gndrod]

The change I am least fond of is Section 110.24.

While I strongly agree equipment ratings in regard to available fault current is extrmeley important, the new criteria for markings in 110.24 is not practical, nor will be that effective, but will be a real pain to enforce and comply with....

Brian,
I really feel for the commercial-industrial on this one. Even though dwelling installs seem to be exempt from 110.24, field marking is becoming more common in resi work in many places too.

 

[acrwc10]

That is already required under the 2008 NEC.

See, I was right, those dirty bass.:grin:

We are still on 05 for a couple of months, and then 08' and all the AFCI's and handle Ties.

 

[brother]

See, I was right, those dirty bass.:grin:

We are still on 05 for a couple of months, and then 08' and all the AFCI's and handle Ties.

What area are you in??? still on 2005, why are they so slow in accepting the the newer version of the NEC?

 

[acrwc10]

What area are you in??? still on 2005, why are they so slow in accepting the the newer version of the NEC?

California, they are usually one code cycle behind and in January we go to the 08'

 

[glene77is]

Dennis,
Just a friendly question.
Are the slots (the long and short ones) on a regular receptical
intended to be an early form of "tamper proof" ?

 

[LarryFine]

Are the slots (the long and short ones) on a regular receptical intended to be an early form of "tamper proof" ?

No, polarization. The grounded conductor is the longer slot on a 120v receptacle, and the ribbed conductor on lamp cord, intended to connect to the screw-shell of a lamp's socket.