- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Shared Neutral
My original musing was based on one of Ryan_618?s replies here , although I suggested a different scenario. There have been proposals that want to get rid of multiwire branch circuits altogether. If multiwire branch circuits were dangerous, the referenced installation would be in a similar category. Indeed, prior to the 2002 NEC (and we?re still on 1999 in California) an installation like this would not require these circuits to have a common disconnecting means in certain installations as now required in Section 210.7(C). Personally, I?d be concerned if two branch circuits were terminated in the same enclosure, common yoke or not.
Craig Wellman, the originator of Ryan?s referenced Proposal, is fairly influential; he?s the ?User? representative on the NEC TCC. I think it?s interesting the two CMP members that supported him were another user and the IBEW rep; the two vulnerable or responsible if someone were hurt by such an installation.
Ryan pointed out Wellman?s proposal was rejected primarily from lack of statistical data supporting it. It may be strange from what I wrote in my response there that I agree somewhat with both the CMP and Wellman.
I agree with the CMP that more data should generally be required where a Proposal suggests additional restrictions. Conversely, what Wellman wishes to correct is an intuitively ?unsafe? condition. He is not simply trying to make a ?safe? installation ?safer.? However, the installation is not inherently unsafe; i.e., even if the circuit failed, the facility doesn?t burn down because it is still properly protected by the OCPD. It doesn?t become unsafe until someone works on it.
The CMP felt that ?training? sufficiently mitigates the dangerous condition for workers and the unsuspecting public be damned. On Wellman?s side and reflecting the IBEW rep?s comment, the financial cost of compliance with the proposal would be virtually nil, especially for new work.
[ October 26, 2004, 12:57 PM: Message edited by: rbalex ]
My original musing was based on one of Ryan_618?s replies here , although I suggested a different scenario. There have been proposals that want to get rid of multiwire branch circuits altogether. If multiwire branch circuits were dangerous, the referenced installation would be in a similar category. Indeed, prior to the 2002 NEC (and we?re still on 1999 in California) an installation like this would not require these circuits to have a common disconnecting means in certain installations as now required in Section 210.7(C). Personally, I?d be concerned if two branch circuits were terminated in the same enclosure, common yoke or not.
Craig Wellman, the originator of Ryan?s referenced Proposal, is fairly influential; he?s the ?User? representative on the NEC TCC. I think it?s interesting the two CMP members that supported him were another user and the IBEW rep; the two vulnerable or responsible if someone were hurt by such an installation.
I don?t either, but the question in my mind isn't usually; "Is it as dangerous as some other installation?" rather, "Is it safe? Or what mitigates the danger?" Charlie B spoke to the mitigating factor for my scenario.
Ryan pointed out Wellman?s proposal was rejected primarily from lack of statistical data supporting it. It may be strange from what I wrote in my response there that I agree somewhat with both the CMP and Wellman.
I agree with the CMP that more data should generally be required where a Proposal suggests additional restrictions. Conversely, what Wellman wishes to correct is an intuitively ?unsafe? condition. He is not simply trying to make a ?safe? installation ?safer.? However, the installation is not inherently unsafe; i.e., even if the circuit failed, the facility doesn?t burn down because it is still properly protected by the OCPD. It doesn?t become unsafe until someone works on it.
The CMP felt that ?training? sufficiently mitigates the dangerous condition for workers and the unsuspecting public be damned. On Wellman?s side and reflecting the IBEW rep?s comment, the financial cost of compliance with the proposal would be virtually nil, especially for new work.
[ October 26, 2004, 12:57 PM: Message edited by: rbalex ]
