4300 SF plus detached building setup

Specific Inspection Topics Electrical Inspections
1

This looks like a way to draw more than 200 amps without tripping a breaker.
Any problems with code?

200 amp meter feeding a 200 amp panel that has 5 breakers as follows:
a. 100 amp feeding house indoor panel that has another 50 amp panel off it.
b. 100 amp feeding exterior hvac’s, panel has a 50A and a 35A in it.
c. 50 amp feeding an oven.
d. 30 amp feding a smaller oven.
e. 60 amp feeding the detached building.

No 200A disconnect present in the main service equip. panel.
House has gas heat with 8.5 tons of Air cond.
The service was underground and size of cable not visible.

2

ok…without seeing the setup and so on I will kinda explain a few things…

1.) Total breaker calculations do not factor in the size of the service, Not sure of the best wording for that but I will give an example.

A typical 200A panel that has 42 spaces…could mathmatically have nearly 600 A of breaker markings…HOW CAN THIS BE…lol…

Well basically it boils down to usage factors and so on and the concept that not everything is on at the same time and so on…

Now the idea of (5) breakers meets the 230.71 allowance of 2-6 disconnects per service without having a main breaker per se…

Well…long story short…the actual demand on this would need to be calculated out fully to know what the total demand is…we simply can’t guess that from seeing a 100A panel inside…might only have 30A draw on it…just dont know…have to factor in these loads…

Again really outside the scope of what any HI should venture into…otherwise their heads will explode…lol…But if you would like to try to do the math I will gladly post the procedure for you…:slight_smile:

Now we can do the calculation math and come up with that the service should be…which actually is WAY outside the HI’s scope…`

3

BUT I will comment on one thing…lol…regardless of doing the CALC…any house I have wired over 3,500 sq feet has always gotten a 400A service…if it needed it or not…

I tell you…the COST difference in a rough in for a 400A over a 200A is just well…double that of a 200A…thehehee…

In other words…when doing the cost for a 200A… lets say 235.00 for 200A panels and breakers you would already buy anyway...just spaced out more...it really is not a issue in terms of additional cost...more SE.....and so on....considering my last electrical price for a 4,000 Sq Ft home the other day was 17,890.00 for the electrical…I think I can throw in another 200A panel…thehehehe

4

I would agree that this outside our scope, however, based on what Brian said, there seems to be a great potential for an over-load.

Based on his information, I might air on the side of caution and recommend that an electrician be hired to perform a load calc or have a service disconnect installed.

Obviously, the lateral is sized by the POCO at their discretion, but the SEC was likely sized for a 200 amp service.

5

Certainly within the thought of having it looked at…most certainly the prevailing option…however on the service disconnect issue…not nearly as clean cut

BUT it NEVER hurts to refer…better to be SAFE than SORRY !

Hell…Send me the specs…all of them and I will do the calc for ya…free…no cashola…no moola…no denero…man I cant spell all the ways to put it FREE…lolololo

I figured I better cut this one short to keep it simple…lol

6

I don’t have all the specs for a load calc.

I always thought that 3500SF and over should have a 400 amp service but with gas water heaters and gas heat it is not as critical.

One thing that will draw some juice on these big houses is when the heat pumps get covered during an ice storm and the aux heat on 2 or 3 airhandlers cuts in for about 85 to 130 amps total. Add to that a couple of electric water heaters, double ovens and two laundry rooms and you see why 400 amps is needed.

7

The Florida IAEI tossed this around. It is possible, using the article 220 rules, to end up with big houses that have very low load calcs.Remember, using the normal calc, all of the general lighting and receptacle load over 3.5kva gets taken at 35% so basically all of that 4500 sq/ft amounts to a tad less than 20a of calculated load. At that point you are really looking at “fixed in place” equipment and adding that up.Worse is the “optional” way you can do the calc. With that one you end up taking everything at nameplate and anything over 10kva at 40%. If you have a lot of electric “toys” that are on at the same time you can have a problem.The scenario is a party. Every light in the house is on, the kitchen is going full blast, lots of hot water being used, doors are open so HVAC is blasting and people are in the pool, the spa and maybe the sauna. The service is sized at 40% of THAT.

8

While a load calc is beyond a home inspection, the Service Entrance feeders from the drip loop or pull box to the service/distribution panel need overcurrent protection that match the wires, which should be verified during the inspection.

This wire protection is most commonly a main breaker/fuses at the service panel, but can be a breaker/fuses at the meter enclosure (combo meter/disconnect) or within a separate enclosure between the meter and panel.

If the SE feeders are sized for 200A (2/0 Cu or 4/0 Al), then that is a defect which should be written up as they could be overloaded (panel breakers total 340A). But since it’s a large house, I guess it’s possible the SE feeders are larger.

JMO & 2-nickels … :wink:

9

Robert,

That totally depends on the Service Setup- In many cases you will have (2) 200A panels with both being fed with 4/0 AL SE which is totally allowed and is rated as a 400A service…yet (2) individual 200A panels…The meter cab itself is usually rated 380-400A and is in most cases provided by the UTY and no cost…could be different in other areas…but in ours they provide it free.

The service can truly be a (2) 200A services with a total AMP rating of 400A…which is what the UTY will figure on when supplying the power to this system.

As as side note…The cost factors in most cases of doing something less than 400A but more than 200A is negatible…and in many cases as a contractor the cost of the 150A panel can be more than the cost of a 200A…depending on the supplier and supply house.

In most cases the houses will be either 200A or 400A…atleast all the electricians I deal with…and myself…and we use a golden rule to save time…if the house is under 3,500 we have to calc. it out…if over 3,500 it is automatically a 400A service…and their are obvious exceptions to every rule…but it helps save time… on the ones under 3,500 we then go into more detail just to make sure…and then let that decide if it is 200A or 400A…but as stated on a 3,400 sq ft and up house…automatically 400A…NOW if it is a 10,000 sq ft and up…thats a whole new ball game…

10

While there are work arounds, a service calc is beyond a home inspection. So IMO a home inspector simply should look for a main breaker or main fuses that match the SE feeders, or it gets written up for further evaluation by a licensed professional. Keeps it real simple … :wink:

JMO & 2-nickels

11

ahhh…I think I was the one saying it is beyond the scope…lol…I was just explaining how we look at determining service sizes…lol…

Nothing more my friend…not really a work around…factual electrical wiring to current standards.:slight_smile:

12

Hey Paul … We seem to look at this issue a little differently, as I tend to think of the exception under IRC E3503.3.1 or NEC 230.90.A that allows 2-6 breakers/fuses totaling more than the capacity of the SE feeders if a load calc is done as somewhat of a work-around.

Perhaps I have just seen too many things done wrong … :roll: … and think avoiding the minimal cost of having an additional single overcurrent protection device that matches the service feeders wires just isn’t worth the risk of additional future load being added without correctly repeating the load calc to ensure the feeders are not overloaded. Murphy’s Law strikes again … :smiley:

JMO and 2-nickels … :wink:

13

Robert,

I believe you are refering to Exception # 3 of the Art 230.90 (A)…however it is common practice to envoke 310.15(B)(6) which allows for 4/0 AL to a 200A panel…the ability to tap the service entrance meter cab into two individual protected panels of combined 400A via this method using (2) individual 4/0 AL cables.

Panels for general residential wiring come in normal 100,125,150 and 200 Amp rated formats…However meter cabs usualy are in a broader range of usage.

It is totally acceptacle for the Electrician to provide the service in this method.

230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception Nos. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard. There shall be no more than six sets of disconnects per service grouped in any one location. For the purpose of this section, disconnecting means used solely for power monitoring equipment, or the control circuit of the ground-fault protection system or power-operable service disconnecting means, installed as part of the listed equipment, shall not be considered a service disconnecting means.

The key is 230.2 supports this…

BUT with that said…maybe I am getting too technical here versus the question…because I seem to have forgotten the question…thehehehe

I think in the end all you can do as the HI is look at the sizes of the conductors, look at the service size at the loop and also look for signs of overheating and so on.

As for calculations…we have just developed the concept of CALC on services under 3,500 sq ft and when they are over 3,500 sq ft…400A automatically unless the house is excessive…BUT it is very rare to need more than 400A in service…to an electrician if more is needed even before calculations take place…it will be obvious to the trained eye…or should I say…BATTLE TESTED eye…lol

No problem mate ( I got the mate part from GERRY…thehehe ) just figured they would like to know how electricians think when sizing and so on.

14

The question isn’t really the sizing of the feeders, which wasn’t posted (and should be verified), or the number of switches to shut off the service. Bruce indicated there was a 200A meter and panel, with five breakers that add up to 340A and no 200A disconnect (breaker/fuses). I’m assuming that it’s also 200A rated SE feeders (2/0 Cu or 4/0 Al per my previous post), which is why he is concerned.

Per IRC E3503.3.1-Exception or NEC 230.90.A-Exception#3 you can have up to 6 breakers/fuses that add up to more that the capacity of the service feeders if a load calc is done that shows the feeders are not overloaded. That is what I look at as the work-around to just providing a main breaker/fuses rated for the same capacity as the SE feeders, and concerns me also.

15

Ahhh…I think I get where you are going…I WAS being overly technical…lol…

lol…I think this is why I offered to do the CALC for him if he wanted me too…as I stated in the original post…always err on the side of caution…while the setup is allowed…the CALC could prove otherwise…

I just happen to be an electrician so I was offering to do the CALC is all…lol…Thanks Robert for sorting that out…lol

16

NP … and I am curious as to what the incoming feeders wire sizes are. If rated for 200A I would write that up for further evaluation … :wink:

17

I think that from a failure analysis approach it can be safely assumed that if any severe overcurrent condition occurs on any of the 5 breakers, that breaker will trip and no further problem will evolve.

The possibility of having several cases of excess current where no breaker trips and therefore placing more than 200 amps total load on the SE cable is very remote (largest breaker present is 100) and would likely only happen in a situation where there are more than two problems and also with a third present like a jammed breaker.

Since the size of the underground SE was not visible and the entire house could be shutoff with 5 breakers in one panel, I did not recommend any further evaluation. If the house had heat pumps with aux heat strips I would have recommended to have the SE verified as good for more than 200 amps.

thanks for the good discussion guys!

18

Exactly…:slight_smile:

19

Be careful with just guessing. The service load would be in the 200A+ range with the significant cooling/range loads, and a few modern appliances (see attached sample service calc).

I’m not sure where the 200A service capacity comes from then … which is the lowest of the meter/panel rating, SE feeders, and main disconnect/OCP (or calculated load to check the SE feeders if there is no main).

If they are say 1/0 Al SE feeders it would be significantly overloaded. The feeders should be visible at the service panel (which I’m assuming is an MLO type).

…

20

Is the MLO type panel where the meter connections are visible? Those are rare around here. Typically you only get to see what ends up in the service panel after the meter base.