Options in lieu of MLO service panelboards

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
So I think we all know that MLO service panelboards are now prohibited under the 2020 NEC. Couple of questions:

1. The wording for meter centers is a little different where "separate compartments" are allowed where for panelboards, its "separate enclosures". Has anyone heard of any discussions between the manufacturers, product standard people (UL?), and NFPA/NEC about options for redesigned MLO service panelboards that would allow separate compartments? While I dont support the nixing of MLO's, I think it as absurd how there has never been any requirement for covering or protecting the bus and lugs in panelboards. I could see something along the lines of what what I-line does as being mandatory.

2. Consider you typical application of where you would have used something like a 1000A MLO service panelboard with 6 200's to feed your branch panels. Has anyone priced out/thought about doing that with 6 separate circuit breaker enclosures (or fused safety switches) instead of just getting a main breaker panelboard? The main breaker pretty much doubles the cost. Last one I did similar to this it was about $4500 for the MLO and $9k with a main breaker, so there is the potential for significant cost savings.
 
I installed a six main panel board just prior to the change. At the time I wondered how anyone could work on it without calling the POCO for disconnect. Added Price of the main breaker was the deciding factor. The customer was involved in that decision. I can see twenty years from now someone saying “this is illegal and must be changed! What kind of hack does that kind of work?”

I would think enclosures with compartments would add considerable size to the equipment.
 
There are a number of UL product standards that are being revised based on the new requirements in the 2020 code.
 
ptonsparky said:
I installed a six main panel board just prior to the change. At the time I wondered how anyone could work on it without calling the POCO for disconnect. Added Price of the main breaker was the deciding factor. The customer was involved in that decision. I can see twenty years from now someone saying “this is illegal and must be changed! What kind of hack does that kind of work?”

I would think enclosures with compartments would add considerable size to the equipment.
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Yeah I think back when split buss panels were legal a 200A main was a spendy item. Perhaps 300 - 400 A frame breakers will come down in price.
 
electrofelon said:
Revised in what way? To harmonize the product standard with the NEC prohibition, or for a revised product that could meet the NEC without a main breaker (would require rewording of the NEC)?
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To provided products with "compartments" that would comply with the NEC rule.
 
I'd be happy to argue that a box with a double thickness wall inside it is equivalent to two separate boxes. : - )

Cheers, Wayne
 
electrofelon said:
Well that's really good to hear. But do you agree the NEC needs to be part of this? Currently the wording is separate enclosure. Hopefully we will get MLOs back in some fashion.
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I do not want to see any type of MLO for service equipment back in the code. (I have been pushing for the isolation of line side parts on service equipment for many code cycles...I had kind of given up, but then the insulating barrier rule came into the code, and the 2020 rules are just expansions of that rule)

The NEC is driving the product standard...the NEC wrote a rule that made the installatio of all of the current multi-meter assemblies a code violation. The product standard is trying to come up with a requirement that will permit that type of equipment to be used and comply with the NEC.

I am happy with the language in 230.71(B), except that in (B)(4) where it talks about a compartment and not an enclosure. The work in the product standards is related to what a compartment is. In my opinion, it needs to be a metal compartment that provides the same protection as the enclosure of a single disconnect.
 
ActionDave said:
I hate it that this is what the NEC has evolved into.
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The NEC has always driven the product standards and the reverse has also been true. Although this one is more complicated as there had been failed proposals for a line side compartment in the NEC for service, the requirement for the insulating line side barriers for service equipment first appeared in UL 67 and not in the NEC.

Without the NEC as a driver, the product standards would have never been changed to prohibit occupancy sensors and other electronic switches from using the EGC as a current carrying conductor to power the electronics.
 
tortuga said:
Perhaps 300 - 400 A frame breakers will come down in price.
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I don't see that happening. MCBs are so cheap to manufacture compared to what they sell for, and many of us on here have gotten job pricing or s.p.a. discounts that are so steep its almost funny. If the manufacturers had any desire to come down in price they could even without the increased volume from the new requirements. If anything they were behind the code change and the increased revenue it will bring. The problem is nowhere near enough competition in the space. Only 4 companies (sqd / eaton / siemens / abb (former ge) that make panelboards and breakers. There are other switchgear and panelboard manufacturers out there but they all use interiors and breakers from those 4 companies.
 
A back-fed breaker with barriers per 230.62(C) could be installed. Manufacturers are making the boot kits that cover service terminals on breakers. This appears to meet the intent, or at least the wording provided.
 
Greentagger said:
A back-fed breaker with barriers per 230.62(C) could be installed. Manufacturers are making the boot kits that cover service terminals on breakers. This appears to meet the intent, or at least the wording provided.
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The boot kits work only where there is a single service disconnect in the enclosure.
The 2020 code makes most of the equipment that was previously used with more than one service disconnect in a common enclosure a violation.
 
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