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Old 07-30-2020, 02:05 PM   #1
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Default Multi gang meter base installation with demand calculations

Hi all,

I am currently in a small disagreement with my local inspector on multi gang meter installations and demand calculations.

Doing the electrical on a house with a small granny suite in the basement. The customer would like to have the suite metered separately from the main part of his house. No problem I'm thinking but called the inspector to run it by him.

House demand is 198 amps calculated load.

What I want to do is install a 2 gang meter base that comes with 400a rated mains and 200a per position. Install a 200a panel for each the main house and the granny suite. The granny suite doesn't need a 200a panel but I have plenty stocked. Each panel will be fed with 250mcm AL.
For the main service conductors, I want to size them based on the demand of the entire house which is 198 amps. I offered to run 500mcm AL main service conductors since I have a **** ton of that stocked as well. According to table D11b I'm good for 338.4 amps. According to him this won't fly.

What he wants to see is, the 2 gang meter base with 400a mains and 200a per position. He then only wants me to install 1x 200a panel for the main house then a 100a for the granny suite. I can run my 500mcm for the main service conductors then install a lamacoid plate on the meter base saying "max fuse size 338 amps" based on table D11b. This is how it will pass according to him.

I questioned since my demand is only 198 amps, why can't I base my main conductors on that? He replied that I would have 2x 200a panels that could potential draw 400amps. I replied that the demand is only 198 amps and it would be impossible to draw 400amps.
I've done many multi unit buildings. My latest was a 24 unit with a 600a three phase main service. There were 24x 100a breakers in the meter stacks. By his logic I should have had a 2400a service?? That isn't how demand works does it?
Driving around town I've seen many multi gang meter installations. One was a 6 gang meter base with 200a mains and 6x 100a positions. By his logic shouldn't it have a 600 amp service on it?

Any help would be great here guys.... I thought I understood demand factors but this guys has me confused.

regards

jmac
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Old 07-30-2020, 02:32 PM   #2
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I take it you can't get a different inspector?

Meterbase labeled "MAX FUSE 338 AMPS"???? I didn't know you could fuse a meterbase.

Riddle me this if we can install a 200 amp panel with 4/0 aluminum and Mark it Max load 189 amps why can't you do what you're suggesting?!?

I agree with the inspector on a 100 amp panel in the granny suite.

Maybe @eddy current can help me wrap my head around why the inspector is telling you what he is...
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Old 07-30-2020, 07:11 PM   #3
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I would have to just assume the inspector thinks the initial 198A calculation is for the main house only and the granny suite changes would be new and just assuming the max as there's no other calculation given.
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Old 07-30-2020, 09:30 PM   #4
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Quote:
Originally Posted by Kevin_Essiambre View Post
I take it you can't get a different inspector?

Meterbase labeled "MAX FUSE 338 AMPS"???? I didn't know you could fuse a meterbase.
Lol, who is that label on the meterbase for? The utility company? There is no fuse on the line side of the meterbase. It could be connected to a transformer along with many other meterbases.

I think the inspector is a little confused
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Old 07-30-2020, 09:34 PM   #5
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@jusmac, you need to use 8-202 for the calculation. If there is more than one meter, it’s no longer a single dwelling.
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Old 07-31-2020, 11:01 AM   #6
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Here's that section for you BTW
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Old 07-31-2020, 04:19 PM   #7
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This is my take on it... Although I probably don't have the full context, I generally agree with the inspectors comments. It comes down to protection and section 14. You can't rely on the calculated loads to protect your conductors. The calculated loads are conceptual only.

Code:
14-100 Overcurrent protection of conductors (see Appendix B)
Each ungrounded conductor shall be protected by an overcurrent device at the point where it receives
its supply of current and at each point where the size of conductor is decreased, except that such
protection shall be permitted to be omitted in each of the following cases:
a) where the overcurrent device in a larger conductor properly protects the smaller conductor;
b) where the smaller conductor
i) has an ampacity not less than the combined computed loads of the circuits supplied by the
smaller conductor and not less than the ampere rating of the switchboard, panelboard, or
control device supplied by the smaller conductor;
ii) is not over 3 m long;
iii) does not extend beyond the switchboard, panelboard, or control device that it supplies; and
iv) is enclosed in non-ventilated raceways, armoured cable, or metal-sheathed cable when not
part of the wiring in the switchboard, panelboard, or other control devices;
With (2) 200A panels connected, tou have 400A worth of potential current available on the main incoming service. Your conductors are only good to 338A. There is nothing stopping the (2) 200A panels from getting loaded up past 338A. If you switched the main breaker out in the granny suite to 100A, you would be all good. Max current potential on the mains would then be 300A.

Think about it this way: if you computed a single family house load at 90A... and installed 100A rated conductors... you wouldn't install a 200A rated main breaker just because you calculated the load at 90A. Your main breaker would be 100A to match the conductors. The breaker is sized for the conductors, not the calculations.

Quote:
What he wants to see is, the 2 gang meter base with 400a mains and 200a per position. He then only wants me to install 1x 200a panel for the main house then a 100a for the granny suite. I can run my 500mcm for the main service conductors then install a lamacoid plate on the meter base saying "max fuse size 338 amps" based on table D11b. This is how it will pass according to him.
Although the 338A looks a little goofy, this sounds like the correct solution to me. I don't think the lamacoid is saying that the meter base should be fused. Instead the lamacoid is implying "MAX COMBINED CIRCUIT AMPACITY DOWNSTREAM OF THE METER BASE = 338A".
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Old 07-31-2020, 05:27 PM   #8
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@908Eng
But it is done all the time. That’s what 8-202 is for.

Think of a 6 gang meter base running 6 x 100 amp panels. Should that require 600 amp conductors for the main?

And the marking of the meter base is also not required. 4-004(22) Requires disconnects or overcurrent devices to be labelled only if table 39 is used to undersize the conductors.

This inspector is confused and making up his own rules
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Last edited by eddy current; 07-31-2020 at 05:35 PM.
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Old 07-31-2020, 05:41 PM   #9
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Quote:
Originally Posted by eddy current View Post
@908Eng
But it is done all the time. That’s what 8-202 is for.

Think of a 6 gang meter base running 6 x 100 amp panels. Should that require 600 amp conductors for the main?

And the marking of the meter base is also not required. 4-004(22) Requires disconnects or overcurrent devices to be labelled only if table 39 is used to undersize the conductors.

This inspector is confused and making up his own rules
Just wait until he finds out about banks of 15 meters... 1500 amps? Lol
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Old 07-31-2020, 06:03 PM   #10
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Quote:
Originally Posted by Kevin_Essiambre View Post
Just wait until he finds out about banks of 15 meters... 1500 amps? Lol
Or an apartment building with 100 units each with their own 100 amp feed.

Those are different though as they have a main, fused disconnect. A 6 gang meter base for a row of townhouses usually does not have overcurrent protection on the main feed
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Old 07-31-2020, 06:26 PM   #11
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I think what the OP needs to remember that a multi-dwelling unit is consistently scaled back (percentages of the total) and you really don't see that in a simple calc with a granny suite.

Cheers
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Old 07-31-2020, 06:30 PM   #12
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Quote:
Originally Posted by Navyguy View Post
I think what the OP needs to remember that a multi-dwelling unit is consistently scaled back (percentages of the total) and you really don't see that in a simple calc with a granny suite.

Cheers
John
65% of the granny suite is pretty scaled back no?
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Old 07-31-2020, 06:35 PM   #13
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Quote:
Originally Posted by eddy current View Post
65% of the granny suite is pretty scaled back no?
Not compared to a 24 unit or 100 unit apartment building... as discussed above.

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Old 07-31-2020, 06:38 PM   #14
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Quote:
Originally Posted by Navyguy View Post
Not compared to a 24 unit or 100 unit apartment building... as discussed above.

Cheers
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Yes but definitely is something the inspector should know. Also, as mentioned above, those have fused mains so are a different situation.

The inspector requesting that this house gets 400 amp conductors for the feed is ridiculous.
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Old 07-31-2020, 07:46 PM   #15
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Quote:
Originally Posted by eddy current View Post
@908Eng
But it is done all the time. That’s what 8-202 is for.

Think of a 6 gang meter base running 6 x 100 amp panels. Should that require 600 amp conductors for the main?
6-bank meter base would need to have overcurrent protection on the main incoming. Max number of services in a hot gutter is (4) with max bussing of 600A. CEC 6-104 & CEC 6-200. Incoming conductors can be sized in accordance with 8-202 but the main OC protection must be sized for the conductors.

Yes, 8-202 is used for equipment and conductor sizing... BUT... all conductors still need overcurrent protection for the conductor ampacity. I can feed a 20-suite apartment building with 400A but the meter stack is suitably protected by 400A fuses.

Quote:
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Just wait until he finds out about banks of 15 meters... 1500 amps? Lol
C'mon gentlemen! Have a little faith! I use big meter stacks all the time! Without exception, big meter stacks are always overcurrent protected to their bussing ampacity. Of course I don't simply add up the meter amps.

On multi-gang meter stacks, the vertical bussing amps is usually less than the main horizontal bussing amps; however the vertical bussing is ALWAYS the same or greater than the sum total of the meter bases connected in the vertical section.

Example: 18-bank 1200A commercial meter stack, 6 meters wide, 3 meters high. Max 200A meter sockets. Horizontal main bussing is 1200A but the vertical bussing on each vertical run is 600A.

If the mains don't have overcurrent protection, it is the sum total of the downstream breakers that dictate conductor sizing. CEC 14-100.

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Originally Posted by eddy current View Post
The inspector requesting that this house gets 400 amp conductors for the feed is ridiculous.
Inspector is not asking for 400A. All the inspector is asking for is to reduce the total breakers fed from a 338A conductor to be less than 338A. Except for the special applications like motors, and table 13, the overcurrent protection simply can't exceed the conductor's ampacity.

Connecting 400A worth of breakers to a 338A conductor is simply not permitted!
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Old 07-31-2020, 08:08 PM   #16
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Quote:
Originally Posted by 908Eng View Post
6-bank meter base would need to have overcurrent protection on the main incoming.
I agree that the CEC does say no more than 4, but a 6 gang fed with 400 amp conductors and NO main disconnect is very common.


Quote:
Yes, 8-202 is used for equipment and conductor sizing... BUT... all conductors still need overcurrent protection for the conductor ampacity.
Incorrect. Services for single dwellings and townhouses with multi gang meter bases (up to 6 is the most I’ve done) do not have protection on the mains.


Quote:
If the mains don't have overcurrent protection, it is the sum total of the downstream breakers that dictate conductor sizing. CEC 14-100.
Also incorrect. My house does not have protection on the mains coming in with 100 amp conductors. if you counted up all the breakers in my house panel, it would equal 4 times that. ( ETA. Of course I have a main breaker in the panel, but there is no protection for the underground feed from the utility transformer)

And which sub rule of 14-100 says what you have implied? I didn’t see it

Like I said earlier, on large meter bases for apartments, yes, there is a main overcurrent but on townhouses or large homes broken up into many separate units it is very common that you do not have protection on the main conductors, no main disconnect and they do not have to equal the total available amps from each unit.
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Last edited by eddy current; 07-31-2020 at 08:50 PM.
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Old 07-31-2020, 08:38 PM   #17
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Ontario Bulletin 6-3-8


Ontario Electrical Safety Code – Bulletins
(4) Five and six gang meter mounting devices

Question
Is it permitted to use five and six gang meter mounting devices?

Answer
Yes, it is permitted to install up to six gang meter mounting devices for the connection of up to six consumer’s services provided that Rule 6-200 2) is complied with.
6-200 2)

Rationale

More than one service box shall be permitted to be connected to a single consumer's service provided:
(a) The subdivisions are made in a multiple or dual lug meter mounting device rated at not
more than 600 A and 150 V to ground; and
(b) The meter mounting device is located outdoors.
A literal interpretation of Rules 6-104 and 6-200 3) does not permit the use of five or six gang meter mounting devices since the number of subdivisions is limited to four, unless a deviation is allowed.

ESA recognizes that approved five and six gang meter mounting devices are readily available and have been used successfully in the past without undue hazard to persons or property.
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Old 08-01-2020, 02:17 AM   #18
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Quote:
Originally Posted by eddy current View Post
I agree that the CEC does say no more than 4, but a 6 gang fed with 400 amp conductors and NO main disconnect is very common.
Thanks for the Ontario bulletin reference. I was not aware that you easterners can use 5 or 6 meters on a hot gutter. I tried to find something here in AB but so far found nothing. This appears to be unique to Ontario.

I see that bulletin gives some much needed guidance beyond the code. I see it also states this:

Multiple meter mounting devices require demand calculations to determine the maximum number and ratings of sub-services. If no demand calculations are available, then the total of the ratings of the switches fed from the multiple meter mounting devices shall not exceed the ampere rating of the meter mounting devices.

It agree it supports your point. If you do the demand calculation, you can size conductors based on the demand load. If you don't calculate you must use sum total of breakers. Fair point. If OP was in Ontario, the inspector and I would be totally wrong. I looked for a similar deviation in NB but didn't immediately come up with anything.

Quote:
Originally Posted by eddy current View Post
Also incorrect. My house does not have protection on the mains coming in with 100 amp conductors. if you counted up all the breakers in my house panel, it would equal 4 times that. ( ETA. Of course I have a main breaker in the panel, but there is no protection for the underground feed from the utility transformer)
This is the exact point I'm trying to make. The presence of a suitably sized main breaker makes all the difference. It is impossible for YOUR house to load up the main service conductors past 100A. In contrast, connecting two 200A breakers to a single conductor has every opportunity to load the mains beyond 338A.

This hot gutter arrangement with main conductors below total breaker amps may be common in Ontario but definitely not everywhere. AB, BC, SK all have a hard limit at 4 meters on a hot gutter. There may be local deviations which are overlooked but I haven't seen any. Because there is no similar formal deviation here, we have to size hot gutter service for the sum total of the connected breakers. This is unique to row-house situations and would not be applicable for standard main fused incoming services.

Can we agree that this is a regional argument? I definitely see your point.
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Old 08-01-2020, 10:48 AM   #19
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@908Eng, It’s surprising to me that other provinces don’t allow more than 4. These meter bases are available everywhere in Canada, not just in Ontario. The CEC even mentions it can be done “if a deviation is allowed” which makes me assume it is done in more provinces than just Ontario. In Alberta, they install main disconnects outside supplying 6 gang meter bases for every row of townhouses?

As for the main feed conductor size, it it spelled out clearly in 8-202(3) that the consumer’s service or feeder supplying two or more dwelling units shall be based on the calculated load obtained from Subrule 1), not the total available amps of each unit. Of course, it does say in the Ontario bulletin, that if there is no calculated load you would have to use the max, but NEVER in residential is there not a calculated load available, and why would a contractor not get one, especially if it means they have to install larger, more expensive conductors if they don’t?

I have wired many multi-gang meter bases on large old houses that were turned into multiple units and never had to provide a load calc. Of course these are small units and the load would be nowhere near the same as 6 full sized townhouses.
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Old 08-01-2020, 01:07 PM   #20
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The 5 or more townhouse arrangements I've seen use two groups of meters. Like this:


To save some feeder length sometimes we group them 3 on one side and 3 on the other. Depends on site, transformer, other services, etc.

I did some street-view in various neighborhoods but couldn't find any examples of more than 4 meters in a bank.
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