when were service main disconnects required ?

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Stevenfyeager

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United States, Indiana
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electrical contractor
house built in 1946 but has had a outside panel replacement so says the customer. Home inspection now requests a main disconnect. What year was this required ? I know I see many older homes with no main breaker, so I assume there were years when a main was not required. Thank you.
 
First, a home inspector can request whatever he or she is willing to pay for.

Second, are you saying there is a split-bus panel or a main-lug panel there now?

Third, do you know when the present panel was installed, or if it was permitted and inspected?
 
The NEC has allowed up to six disconnects for a service for a long, long time. Not entirely sure but I would guess 1946 is in the ballpark for how old that rule is.

Unclear from your post if the home inspector actually knows what they are talking about when they say there isn't a main disconnect.
 
Stevenfyeager said:
house built in 1946 but has had a outside panel replacement so says the customer.
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What do you mean "outside panel replacement?" As it's been explained to me before on this forum, and I'm just trying to help, you need to get your terminology right for anyone on here to assist you. Are you talking about the meter socket? And if so, who upgrades the exterior service drop but leaves the inside without a service disconnect?

All panels now-a-days are going to have a service disconnect, but not always in the same enclosure as the branch circuit OCPD's. Other than that (i.e. the service disconnect being separated from the branch circuit OCPD's) the only thing I can think of is older, fused panels.

I remember in my early days, I used to hear some guys used to talk about the meter socket as the first point of disconnect (n.b. this is before the existence of emergency disconnects in the meter socket enclosure) and there were arguments as to whether or not that was accurate, but that's not how we typically think about it now-a-days.

It might be the case, that way way back in the day, yanking the meter was the original emergency disconnect, but don't quote me on that, lol.

Stevenfyeager said:
Home inspection now requests a main disconnect. What year was this required ? I know I see many older homes with no main breaker, so I assume there were years when a main was not required. Thank you.
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Either way, you need a service disconnect. Is this question just for the purpose of an academic history lesson?
 
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Up until the 2020 code, the disconnect means could be inside (unless trumped by a local code) and that could ALSO fall under the 6 disconnect rule, which in older home may have been the entire service. So it may APPEAR there is no “main” but it may have been fine under different rules.

As of the 2020 code all single family residences must have an external disconnect if there is NEW construction.

But if the installation met code at the time it was done, there is no retroactive enforcement. So your Home Inspector is likely over interpreting, misconstruing, or just plain ignorant. But we can’t see it so we can’t tell you for sure.
 
Stevenfyeager said:
house built in 1946 but has had a outside panel replacement so says the customer. Home inspection now requests a main disconnect. What year was this required ? I know I see many older homes with no main breaker, so I assume there were years when a main was not required. Thank you.
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Do you have any photo's of the equipment?
 
Jraef said:
Up until the 2020 code, the disconnect means could be inside (unless trumped by a local code) and that could ALSO fall under the 6 disconnect rule, which in older home may have been the entire service. So it may APPEAR there is no “main” but it may have been fine under different rules.

As of the 2020 code all single family residences must have an external disconnect if there is NEW construction.

But if the installation met code at the time it was done, there is no retroactive enforcement. So your Home Inspector is likely over interpreting, misconstruing, or just plain ignorant. But we can’t see it so we can’t tell you for sure.
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But the way it is worded the "service disconnect" can still be inside and you can still have the required "emergency disconnect" on the outside. That emergency disconnect not need to even be on the same structure just on the same premises from what I understand.
 
Jraef said:
[This] could ALSO fall under the 6 disconnect rule, which in older home may have been the entire service.
So it may APPEAR there is no “main” but it may have been fine under different rules.
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Now that's interesting. I never thought of the older, fused panels as each individual fuse being 1 of the 6 disconnects.
But now that you've said it, it clicked.
 
jaggedben said:
1933 according to this:
www.ecmag.com

The Six Disconnect Rule: The 2020 NEC revision has major impacts on electrical installations

Sometime between the 1925 and 1933 National Electrical Codes , the maximum number of service disconnects changed from one or two disconnects to a maximum of six. I cannot verify the exact edition where the change occurred. I have original copies of the 1925 and 1933 NEC books and the 1933...
www.ecmag.com www.ecmag.com
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Interesting article. Good read.

Crazy to think that, essentially:
Pre 1933 - Required to have one or two....
Post 1933 - Single could be omitted, up to 6
Post 2020 - Required to have one...

So in 2020, we've essentially and very simply put, reintroduced a requirement from pre 1933?
Am I understanding that correctly? lol
 
Jerramundi said:
Post 2020 - Required to have one...

So in 2020, we've essentially and very simply put, reintroduced a requirement from pre 1933?
Am I understanding that correctly? lol
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You are not understanding it correctly. Up to six service disconnects are still allowed (as in Post 1933). However, they are no longer permitted to be in a single enclosure...they must be in separate enclosures.
 
david luchini said:
You are not understanding it correctly. Up to six service disconnects are still allowed (as in Post 1933). However, they are no longer permitted to be in a single enclosure...they must be in separate enclosures.
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Thank you for the added clarification. You are correct. Up to six is still allowed and I could see how someone could misinterpret the joke I was making and it's important that misinformation is not spread, but I think you misunderstood what I was attempting to say, in a somewhat humorous fashion.

According to the article, pre-1933, you were required to have one or two disconnects.

Post 1933, this requirement could be omitted and allow up to 6 in a single enclosure... and as previously stated, I never really thought about the old fused panels with no singular main, as being the 6 disconnects (i.e. not one). When I hear 6 disconnects, I think large commercial system or apartment complex.

Now with this change, since they have to be in separate enclosures, that post 1933 interpretation could no longer be applied to the 6 fuses in a single panel, or in other words, forces us to have one disconnect, in specific regard to how it applies to the example of the old fused panels in single family residences.

In that way, it's my understanding that it has gone from 1 to 6 to 1.

But yes, ultimately you are correct. Up to six is still allowable and it's important no one misinterprets what I was trying to say, humorously, and misunderstands the code. If there's still something I'm not quite interpreting right please feel free to clarify further, but my initial comment was just a joke about somewhat reinstating an old rule, in a very particular context.
 
Jerramundi said:
Thank you for the added clarification. You are correct. Up to six is still allowed and I could see how someone could misinterpret the joke I was making and it's important that misinformation is not spread, but I think you misunderstood what I was attempting to say, in a somewhat humorous fashion.

According to the article, pre-1933, you were required to have one or two disconnects.

Post 1933, this requirement could be omitted and allow up to 6 in a single enclosure... and as previously stated, I never really thought about the old fused panels with no singular main, as being the 6 disconnects (i.e. not one). When I hear 6 disconnects, I think large commercial system or apartment complex.

Now with this change, since they have to be in separate enclosures, that post 1933 interpretation could no longer be applied to the 6 fuses in a single panel, or in other words, forces us to have one disconnect, in specific regard to how it applies to the example of the old fused panels in single family residences.

In that way, it's my understanding that it has gone from 1 to 6 to 1.

But yes, ultimately you are correct. Up to six is still allowable and it's important no one misinterprets what I was trying to say, humorously, and misunderstands the code. If there's still something I'm not quite interpreting right please feel free to clarify further, but my initial comment was just a joke about somewhat reinstating an old rule, in a very particular context.
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There was typically two versions of the "main, range, and four plug fuse" panels. The 60 amp version the main was the main for the entire panel. The 100 amp version the main only disconnected the four plug fuses and the sub feed lugs, the range fuse block was a second service disconnect.

There also was bigger fuse panels that were like the split bus breaker panels in that there was a lighting main and other pull out fuseholders that were also mains.

There also was quite a few 200 amp pushmatic panelboards that had main lugs and 2- 100 amp main breakers that fed two columns of bus within same cabinet.
 
kwired said:
There was typically two versions of the "main, range, and four plug fuse" panels. The 60 amp version the main was the main for the entire panel. The 100 amp version the main only disconnected the four plug fuses and the sub feed lugs, the range fuse block was a second service disconnect.

There also was bigger fuse panels that were like the split bus breaker panels in that there was a lighting main and other pull out fuseholders that were also mains.

There also was quite a few 200 amp pushmatic panelboards that had main lugs and 2- 100 amp main breakers that fed two columns of bus within same cabinet.
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One I've never encountered is this fabled 30A I've read about, only as low as 60A, but I hear they were once a thing too.
Can't imagine running a house on 30A or 60A. Useful information though, thanks.

I was just saying that, I never really thought of the individual fuses as being service disconnects and that's an interesting idea.
 
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Jerramundi said:
One I've never encountered is this fabled 30A I've read about, only as low as 60A, but I hear they were once a thing too.
Can't imagine running a house on 30A or 60A. Useful information though, thanks.

I was just saying that, I never really thought of the individual fuses as being service disconnects and that's an interesting idea.
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Seen a few open blade switches with 30 amp plug fuse holders, that likely were the original service switch at one time but were still in place and in operation supplying some old K&T wiring. Some were still sort of service disconnect though an improper one. They upgraded and installed "main, range, four plug fuse box, elsewhere in the house, but still ran a separate feed from meter to that old 30 amp K & T service, so you basically had two service disconnects not grouped in the same location in those situations. Often that 30 amp switch and fuse holder was in the attic somewhere (back when there was commonly permanent stairs to the attic) and was a fuse in both grounded and ungrounded conductor.
 
Jerramundi said:
One I've never encountered is this fabled 30A I've read about,
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I have. Once. Knife switch with screw-in fuses. It allmost certainly fed a fuse box elsewhere in the house originally, but by the time I came it fed a normal looking 125A subpanel next to it. With 10awg wire, iirc.

We connected about 10 or 12 solar panels on micro-inverters to the subpanel. All good. :D

Jerramundi said:
only as low as 60A, but I hear they were once a thing too.
Can't imagine running a house on 30A or 60A. Useful information though, thanks.
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Until recently, when people started electrifying, most houses in my area would never draw 60A. Seen quite a few services like the one above (well, the fuses were more modern) that were 60A instead of 30. One fed two meters, each of which fed a pretty full 100A panel.
 
Ooh, now you're bringing back a bad memory, too. On one of those aforementioned 60A services we installed a solar inverter that included a 32A level II EV charger. The plan checker approved the plans, but the inspector refused to accept my perfectly by-the-book 220.83 load calculation. I think it came in at around 58A. He didn't question my math or calcs or list of loads, just said "I refuse to approve the addition of a 32A EV charger on a 60A service." I had to admit I was cutting it close and he kinda had a point. Fortunately the customer agreed to pay to upgrade the service to 100A.
 
jaggedben said:
Ooh, now you're bringing back a bad memory, too. On one of those aforementioned 60A services we installed a solar inverter that included a 32A level II EV charger. The plan checker approved the plans, but the inspector refused to accept my perfectly by-the-book 220.83 load calculation. I think it came in at around 58A. He didn't question my math or calcs or list of loads, just said "I refuse to approve the addition of a 32A EV charger on a 60A service." I had to admit I was cutting it close and he kinda had a point. Fortunately the customer agreed to pay to upgrade the service to 100A.
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Probably was time to retire that thing, but at same time what code could he cite as a basis for rejection?
 
Jerramundi said:
One I've never encountered is this fabled 30A I've read about, only as low as 60A, but I hear they were once a thing too.
Can't imagine running a house on 30A or 60A. Useful information though, thanks.
Click to expand...

Very common in the 40s and 50s to install 60 amp services. Range was the biggest user, heat and hot water were by fossil fuels. Or you could heat water electrically and use gas for the range.

My parent's house was built in 1949 and I upgraded it to 200 amp service, in order to sell, after their passing in the late 2000s! Gas heat and hot water, was originally oil. A few small window units. Never replaced either 60 amp fuse.

There were houses near us that had 30 amp 120 volt services. Again, gas heat and hot water and a few fans back then. Richmond City had the gas system and fed everyone they could until the moratorium in the 70s. Also apartments in the "Fan District" (named because the streets were not parallel, but diverging) were all 120 volt 30 amp services. Modern looking safety switches outside replaced the original knife switches located inside.

Only the introduction of modern HVAC systems caused the uptick in upping service size, right, Larry? ;)
 
I saw at least four 120V services on homes in the Bay Area post 2011. One was a potential customer and I got to look in the panel and was horrified, I think I posted a pic here in the forum as a 'how many code violations can you count?' kind of thread. PG&E had replaced the drop at some point but the 2nd leg was just taped up at the weatherhead. The next two were three-story Victorians in my neighborhood, which at some point I noticed only had one insulated wire on their drops. (They were right next to each other, I assume PG&E put one on each leg.) They got upgrades within a couple years of when I noticed them. The last one, which was probably in 2017, she didn't even have a weatherhead. The service conductors were knob and tube that entered the exterior wall through those porcelain insulators. Only time I ever saw that. She was already getting an upgrade when she contracted with us for solar.

All of the above weren't more than 60A services.
 
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