open neutral...big problem

[don_resqcapt19]

...
As far as AFCI's I've put in a hundred or more, GE's are the best. ...

When did GE start making their own combination type AFCIs? When the combination type were first required the GE AFCIs were being made by Siemens.

 

[dwellselectric]

That's why you always pig tail the neutral when running a mwbc

 

[kwired]

I woul say that the intent of the two pole AFCI Breakers are 240 volt loads like window A/C and Electric baseboard heat.
I don't think that running MWBC for 120 volt loads is a good idea but if you do
you need a two pole AFCI breakers

There is currently no AFCI requirement for 240 volt loads. If that is the intent then the manufacturers will push hard to make this a requirement also.

 

[LEO2854]

There is currently no AFCI requirement for 240 volt loads. If that is the intent then the manufacturers will push hard to make this a requirement also.

Thats right . I am sure that the maufactures will puch big time and they probably snuck it in the 2011 NEC,Hope not they are $80 each.

 

[e57]

"And while running only two wire branch circuits makes you feel better - they still will originate from a multi-wire system."
-That's why we put branch circuit OPD's at the point of distribution.

OCP won't help in a 'High/low event' (Lost neutral). Although manufactures could easily make an OCP that would - they don't... Thermal magnetic OCP is often 'tricked' by ohms law in a high/low due to the voltage changing.

 

[reddy kw]

I woul say that the intent of the two pole AFCI Breakers are 240 volt loads like window A/C and Electric baseboard heat.
I don't think that running MWBC for 120 volt loads is a good idea but if you do
you need a two pole AFCI breakers

Actually, that was my whole point-I don't like MWBCs for 120 volt branch circuits, for previously stated reasons. I prefer one hot, one neutral, one ground.
If supplying an individual branch circuit of 240, 120/240 or 120/208 volt, to single-or 3-phase loads, that's completely different. I'd never put a 120 volt load on one side of an existing 120/240 3-wire 15-or 20-amp MWBC.
I'm no genius, nor am I an engineer. I'm just a sparky. So yeah, I do listen to the 'so called experts'.
None of my installations ever caused fire or injury (I started in 1986- GFCI's were only used outdoors and in bathrooms, and nobody had heard of AFCIs). Always believed careful craftsmanship is the cornerstone of safe, long lasting installations. I'm preaching to the choir here.
Are electrical systems safer now (with AFCIs and GFCIs) then in 1986? I don't think they're less safe.

 

[hardworkingstiff]

But it still acts the same when the noodle is opened.

That's a technical term, right?