Ok guys. My friend has gone and replaced his 100 amp panel with one of 200 amp capacity.

Problem: He did not arrange this upgrade with the Power Co. Therefore, I suspect that the Power lines from the Power Co., along with the meter and the SE cable from the Power Co. drop to the Panel is of insufficient capacity. He did not change the meter nor the SE wires (as I said, no prior Power Co. arrangement/no permit obtained). I suspect that the existing SE Conductors and the Meter are rated for 100 amp service!!!!

How do we go about determining the sizing of the existing conductors AND of the meter? I know (think) that the SE conductors must be 2/0 for 200 amp service. I have looked at the conductors coming into the panel, and I find no sizing info stamped on the insulation.

Q: is there a sizing tool available that I can use for this large conductor?

The Meter: I have looked at the Meter, and I find no info as to the amp rating of that Meter. isn't this info supposed to be labeled on the Meter?

I do not plan on doing any work on this property. He is the owner, and I wish only to advise him and help him determine whether or not he does, in fact, need to correct anything. If he does, I will advise him to pull a permit and do the job himself, as this is what he wishes to do - he doesn't want to go the expense of hiring a contractor. He is very adept at doing this type of work, although, why he didn't think to check the Meter and SE conductors, escapes me.

Summary Questions: How to determine the existing capacity of the SE Conductors AND How to Determine the Meter's Rating?

-Terry

 

I just had this conversation recently with my step father as I too have a 200 amp breaker box in a home I just bought but I personally didn't think the conductors were proper. He is a 45yr electrician so I figure he was the guy to ask. He told me for 200 amp service, what he would use is 3/0 conductors. Not sure if 2/0 would make a big difference but 3/0 is what he told me.
Don't feel bad I have number 3 conductors with a 200 amp breaker and a no ground right now. I may be a phone guy and not an electrician but I do know that the breaker box should be grounded and how to do that much. I hope this helps. I must be going now, I have to go check on my breaker box and make sure its not smoking yet.

 

They used to use 2/0 for residential and I wouldnt lose any sleep over that,,, but thats a big difference from No.2 that might be used on 100 a service. You should be able to see that without having to measure it,,, its obvious. 2 is a bit samller than a pencil maybe and 2/0 is going to be little finger size or so.

 

200 amp can be supplied with 1/0 if the run is not too long. the longer the run the larger the wire. This run is all the way to the transformer, not just to the meter. (It is possible that the wire to the meter from the transformer would also need to be replaced)
And yes most meters have the voltage rating stamped in the nameplate - unsure call the utility company.

 

I'm just a DIYer and not an electrician, but here's my opinion...

The potential downside of this situation is enormous, while the upside of not investigating the matter is perhaps saving a few dollars.

The only people who can tell you the correct answer with absolute certainty is the power company. Call 'em and arrange for a visit from them. It'll probably be free, it could save you a house fire, and will allow you (your friend, whoever) to sleep soundly at night.

I'd say those are all very good reasons to check the situation out with qualified people and arrive at a definitive answer.

 

It is only common sense that you would need to change the wire size when you upgrade your panel fromm 100 amp to 200 amp. Personally, I think a 100 amp service to a house is plenty, unless you are growing weed where you have a bunch of hps lights going. A 100 amp service is good for 100 amps on each leg. You could have 200 amps if it is split up right. Most people are looking to add more circuits and the panel is full. They have 100 amp panels that have more spaces. Don't get me wrong, If I built a house I would put a 200 amp service in it, but only to get the 42 spaces. Just my professional advice.

 

I would install 200 also,, always do,, almost the same expense,,, but there is anothere reason that I do. It forces the power company to put a bigger wire on. I just look at one a guy installed a 100 for a garage,,, wanted to have this great service. Ha,,, He actually would have had better to subfeed from his house. The runs were long and they ran a dinky wire where the house wire was fairly substancial. I put 400 in for that reason and I talk to the engineer ahead of time and the crew too. They bring me a monster wire,, real improvement. I tell my neighbor to call the power quality guy,,, junkie old kettle then they use a tiny wire for 150 ft run,, lights bounce all the time. I love the code,, we gotta use 3/0 coming down the pipe,,, then the poco hooks a number 4 alum wire on it.

 

About meter ampacity:
In my neck of the woods anyway, all meters that the power
goes directly through, are 200A 2 pole (on residential/farm
service anyway).

 

There are 100amp meters and 200 amp meters.

 

I have wondered about this. Does this mean that a 200 amp main breaker can handle 400 amps ("if it is split up right")?

Of course, I realize that a home is very unlikely to have appliances that will require 400a. Just wondering about the Theory of it all. Please tell me how a breaker can handle more than it's rated current draw.

And by the way, the original topic problem of this thread has been
solved. The meter was, in fact, rated 200amps, as were the SE cables.

-Terry

I should note, that I know that the service needs to be balanced, so that there will be an equal amount of current drawn on both legs if everything in the home is turned on at the same time. HOWEVER, I'm not sure how one can guarantee that the load will, in fact, always be balanced since there is apt to be different circuits in use at different times - I mean, there could be times that leg A will be drawing, say 75a, while leg B might be drawing 50 or 100a.

 

two pole breakers are rated on each pole. ex. If you have a 2 pole 20. either phase has to exceed 20 amps. Now if you are talking about mains in a panel, the same applies. a 100 amp main breaker could draw more than 100 amps. Not that it is ever likely in a house, but you could have 90 amps on one leg and 90 amps on the other leg. This means you are drawing 180 amps. The breaker is protecting the wire comming in as well as the buss in the panel. There are two wires and two buss bars.

 

I have done the 100/200 amp upgrade that is being talked about here. And I am getting a ton of "bouncing" on my lights. This has happened since the upgrade...I have had the power company out to the house twice and they have replaced both the neutrals and the power lines. I don't know if they changed the gauge of the wire however, even though I told him of the 200 amp upgrade. Only problem is the job was never inspected so they haven't officially gotten word of the upgrade. I am told that when the inspector comes in, I get a cert for the power company. Will they then come back to the house and change the drop??? Will the constant, incessant dimming of the lights stoP????? Please help!!!

 

It can be from their transformer too,,, some old piece of junk maybe

 

Find the breaker that controls the lights that are bouncing and shut it off. See if you have a washer or other motor type load on that branch circuit .

You may have a branch circuit that you may need to get a large load off of.

Your bouncing of lights can be caused by either a main service or a single branch circuit.

See if your lights that are bouncing are on the same branch circuit. YOu may have more than one branch circuit that you may need to split.

Could be the service is your cause but also could be a branch circuit where lights and a motor load is sharing the same branch circiut.

Hope this helps

Wg

 

You have said that it started after the upgrade. This tells me it is something that you did (or didn't do) Turn the main off and check all connections Including your grounds (whites and bares) Make sure your water line and ground rod is bonded with your grounding conductor comming in. Check connections on the load side of the meter. Make sure main is off first!!
Let me know if this helps.

 

JUST ONE MORE TIDBIT...
The average house with with electric range and dryer, gas heat and water heating does not exceed 30 amps per leg except for VERY breif periods when a couple of compressors or motors come on at the same time, even then usually only spiking in the 45-60 amp range.
Very common to only have draw in the 20s...
And you can ask power company to upsize the conductors if you like, for additional cost. But remember - overhead services have weight/distance factors to comply with thus limiting size. Underground only connection lugs limit size.

 

Yes,,, one of my buds,, a master ,, says that even all electric house as long as it doesnt have big ac and heat rarely ever sees more that 80 a. The only time I come across panels really loaded is in bar or restaurant kitchens where they add stuff on to the limit,,, Fryday night fish fry in the summer,, ac units running full as well as stove vent fans and elect fryers. I tried to get one to go to gas french fry,,, but they like elect. Then add a broaster too. Micros,, 2 or 3 Coolers screaming, ice maker. Houses rarely see much load.

 

I would just like to comment on the original post. While you are correct that 2/0 copper is the correct size for the 200 amp residential service, it was mentioned that the wires "were not marked or labelled."

This may lead into problems with an inspector. The National Electric Code specifically states somewhere in Article 300, I think, that any wires used must be clearly and legibly marked. That is an actual code. An inspector would rarely take the time to measure the thickness of a wire, and probably would not have the tool to do it, since the code says it must be marked anyway.

I would recommend replacing the wiring with wiring that is marked as to it's size, type, and voltage rating. It may not pass an inspection the way it is, if the inspector notices this. Hope this helps.

The Captain.

 

About the meter:

Normally there is a label inside the meter which will state the manufacturer and the electrical data (ampacity, etc.). I don't know what to tell you if it is not there.

Usually an inspector wants to see a label, at least that's been my experience. Usually, an inspector determines if the electrical equipment is "approved" by looking for this label.

Is there a company name anywhere on the meter socket at all? Anything more to go on?

 

Just to clarify:
Original upgrade work has been checked throroughly twice, by 2 different electricians....all connections are tight.
Bouncing occurs on all circuits...even new ones run since the upgrade with not a lot of lighting on them...seems to be affecting the entire house.....so one circuit is not the problem....
any ideas......

Jason

 

It sounds like you had people check it but you don't mention an inspector.

I would say to get a permit, and have it inspected by your municipal electrical inspector.

 

If you have around a 2000 square foot house or larger and have electric range, electric dryer, electric water heater, central a/c or heat your 200 amp service may not be large enough to carry what you have. To solve the minimum service size as required by the NEC try the following link that provides a format to calculate the residential demand load calculation as required by the NEC to serve that home. Then you at least will know what size your service is required to be compared to minimum service size required by Article 220 of the NEC.

http://www.homewiringandmore.com/hom...DmdCalc02.html

If your calculation results says your service is of adequate size then start suspecting a loose connection, improper breakers listed for that panel, undersized overhead drop utility owned, undersized transformer utility owned.

Let us know what you find and good luck

Wg

 

You are describing a loose neutral, or a bad main breaker. Did you put in a new panel or was it used. It is hard to give advice like this, but look carefully at the main breaker. Grab it firmly and move it side to side. see if it moves on the buss or is it fast. You could have a loose wire in the meter can. Turn off main breaker to house and tighten all connections in the meter can. If all fails, Call an electrician.

 

Where a rubber glove before you start pulling and shaking and twisting any breakers like you are being told to do.

 

first of all i don't think it really matters what the size of service drop wires are, because it is on the line side of the meter so u r not paying for the voltage drop. and if they burn up ;they have to replace them..... As for the lights dimming, Most electricians run 3-wire homeruns now which will usually make lights dim if you are using a large load on either the two circuits. There is really no way to prevent it, when my 220 water pump kicks on the lights dim and i ran two wire sizes larger then the recommmended. The best way to prent it is to keep you lights on separate circuits the the plugs so if you turn on the vacuum you won't see the lights dim Just some words for thought

 

Hello everyone

In regards to service conductor sizing, the 1999 NEC states in table 310-15(b)(6) for single phase residental dwelling services & feeders that for a 200 amp service it is permissible to use wire no smaller than 2/0 copper or 4/0 aluminum for the hot wires. Aluminum is very common for service wire, so be sure to note which kind is installed!

Also, main breakers and other types of two pole breakers that are used to feed a three wire (opposing phase wires & a neutral) can not carry "twice the rating on the breaker". This is because the currents on the two hot wires are 180 degrees out of phase. The neutral carries only the difference current, if the currents on the two hot wires are exactly equal the neutral carries no current at all. With this in mind, it can be seen that a 100 amp main breaker carries 100 amps and no more except for the occasional brief spike from motor starting and so forth.

 

Spike while I agree with your statement that a 100 amp breaker can only carry 100 amps phase to phase. However you have two hot conductors both being capable of carrying 100 amps each. If you carry 100 amps on phase one to the center tap of the transformer, you would have 100 amps pulling through say the left side of that double pole breaker that is 100 amp rated. How many amps do you believe is being pulled on the left side of that double pole breaker if phase two has no load on the second half of that buss bar not in contact with the first half? Now how many amps can you pull on phase two on the right side of that double breaker back to the center tap of the transformer without adding amps to phase one being the left side of that double breaker?

Curious

Wg

 

Hello WG

I hope that I have understood your post correctly. Going on that assumption, here goes.

100 amp single phase 120/240V panel fed with 2 hots and a neutral. 100 amp main breaker. For simplicity all loads are purely resistive, the power factor is 1, and the AC is pure sine wave with no harmonic trash on it.

If Hot #1 (phase 1) has 100 amps on it & Hot #2 (phase 2) has 0 amps (no load), then the neutral (transformer center tap) will also be carrying 100 amps.

If Hot #1 still has 100 amps on it & Hot #2 now has 50 amps, partial phase cancellation will now take place on the neutral and it will carry 50 amps. Adding this load on Hot #2 does not affect the 100 amps already flowing on Hot #1.

If Hot #1 still has 100 amps on it & you bring Hot #2 up to 100 amps also, complete phase cancellation will now take place on the neutral and 0 amps will flow on it. Again, adding this additional load on Hot #2 does not affect the current already flowing on the other hot wire. Under this condition of perfect balance, the circuit could be viewed (from a voltage, current, & power perspective) as a single 2 wire 240 volt circuit with 100 amps flowing in it giving 24000 watts of power.

At no time does more than 100 amps flow through the main breaker.

It is probably better to look at this from a power (wattage) viewpoint. The maximum power that the 100 amp panel can provide is 24000 watts (240 Volts X 100 amps=24000 watts).
A 200 amp panel can deliver a maximum of 48000 watts.

Of course, in the real world, nearly all loads have reactance as well as resistance so the power factor is usually not 1 and Harmonics from various sources cause sine waves to not be pure, etc. etc. Because of these factors, you will probably not ever see the perfect theoretical situation outlined above.

Sorry for the long-winded post.

 

so spike, did you answer the question?? So if you go by watts, that means that one leg on a 100 amp breaker can carry 200 amps as long as the other leg doesn't pull anything? 200 x 120 = 24000 as well.. so since the breaker goes by heat, watts= heat, so as long as the feeders are using less than 24000 watts no matter how much is on each leg it will not trip. are we on the right track

 

This is what you wrote
If Hot #1 still has 100 amps on it & you bring Hot #2 up to 100 amps also, complete phase cancellation will now take place on the neutral and 0 amps will flow on it. Again, adding this additional load on Hot #2 does not affect the current already flowing on the other hot wire.
I agree. But in a panel you are not talking about a 2 pole load. You have a bunch of 120v. circuits on both sides of the panel. If you load up both sides of the panel, it is possible to have 100 amps on each pole. The unbalanced load between the two is what your nuetral will carry. So, if you had 100 amps of 120v loads on A, It is possible you could have 100 amps of 120v loads on B, Your voltage would be very low if this ever happened,but it is possible.

 

Not likely, breakers trip on the amount of current. Any internal heating element would operate based on the current flow across a given resistance, as per Ohms Law. I was trying to illustrate the difference between a 100 amp vs 200 amp panel using a different way of looking at things. 120V X 100A = 12000 watts. 12000 watts on each 120 V leg. 12000 X 2 = 24000 watts. 240 V X 100A = 24000 Watts. It works however you look at it as long as you use the equations in the correct context.

A 100 amp panel is not a 200 amp panel.

 

bwetzel,

My previous post was in answer to Canoe875.

I understand what you're trying to get across. The way I look at it is to view the entire panel with all its branch circuits as a single two wire 240 V circuit when it is in perfect theoretical balance. The reason I got into the wattage thing is that it can help clarify if used as an alternative way of looking at things. If both sides of your 100A panel are fully loaded to 100A each, then each side has 100A X 120V = 12000 watts. Both sides together are 12000 watts X 2 = 24000 watts. By the same token, looking at the overall 240 V circuit-- 240V X 100A is also 24000 Watts.

If the board is not in perfect balance, with neutral current flowing, it is easier to view each side as a separate circuit. But even so, the total power never exceeds the 24000 watt maximum.

 

Spike is saying it right. The panel is a 100 amp rated panel much the same as a branch circuit is sized by the weakest link or smallest wire on that circuit. If you had a 12 awg 20 amp rated wire feeding an entire branch circuit but put one 14 awg amp rated wire on that circuit then the breaker must be sized by that weakest link and now is considered as a 15 amp branch circuit although most of that branch circuit could carry 20 amps. The 15 amp wire in that circuit limits the size rating of that branch circuit.

Now go to the panel we are talking about as spike was saying at 120 volt rating we could theoretically pull 100 amps each hot line to the center tap of the transformer. Yet the weakest amp capacity of that panel would be 100 amps if you are considering amps only becuase from phase to phase you could only pull 100 amps through that breaker. Therefore this panel would be sized by the lowest amps capable of being pulled in any way. 220 volts phase to phase would be pulling 100 amps only as a maximum. That is why the 100 amp name is rated on that double pole 100 amp breaker but yet 200 amps could be pulled on phase to neutral loads.

Maybe around the block type explanation and a lot of generic terms and statements were made but the attempt to help understand in laymen's terms needed the general statements as were produced in this thread. Any way you put it 120 phase to neutral or 240 phase to phase. you can only pull 24000 watt or VA. which would be the common denominater of the two current flow styles.

Sounds like we sorted it out enough to draw the picture for those that needed the help

Good Luck

Wg

 

ok. So a 100 amp panel can supply 200 amps. So im want to know that if one phase pulls more than 100 amps will the douple pole breaker trip?

 

YES, A breaker is only good for what it says. A 100A 2 pole breaker can only handle 100 Amps on each leg. This is where I said you could have 200 amps through this breaker because you have 2 poles. The 2 pole breaker is protecting two legs at the same time. If either leg excedes the rating of the breaker it will trip.

 

Now, summarizing all this in as few words as possible:

If I currently have 100-amp service, and I have a total household load which will pull 200-amps, I need not go out and buy a 200-amp panel with a 200-amp Main Breaker?? I need only to balance the 200-amp load in my current 100-amp panel in such a way that each leg (phase??) will pull no more than 99 amps? I will be allowing for 198-amps to be divided equally on each leg??

bwetzel said that "A 100 amp service is good for 100 amps on each leg. You could have 200 amps if it is split up right". But then Spike said that "A 100 amp panel is not a 200 amp panel".


-Terry

PS: I knew I would not be able to summarize this in a few words

 

Looks like now we have arrived at what you really have been wanting to know. Bad news the breaker size does not dictate the service size. The service size dictates the service conductor size. the service conductor size dictates the breaker size.

The service size is requried in Chapter 2 of the NEC to be calculated by a demand load calculation that dictates the minimum service size based on 240 volts. See the following link that provides a format for you to perform your own demand load calculation. Notice that the damand load calculation is calculated entirely in volt amps [approximate watts]. Also notice that the final figure in volt amps that you arrive with is then divided by the apparent voltage being 240 volts. This privides your minimum service size per 240 volts. Then each of your hot service conductors must be sized in ampacity equal to that demand load calculation answer in amps. Then the main breaker and main service rated panel must be sized equal to the ampacity of the service conductor ampacity rating.

Then the neutral can most commonly be sized two sizes smaller without being challenged by your AHJ.

http://www.homewiringandmore.com/hom...DmdCalc02.html


Hope this helps

Wg

 

Terry, I must concede the point that Wg and bwetzel were making. You can draw 200 amps from a 100 amp panel if you are considering ONLY 120 volt loads and they are equally balanced between the two hot wires. You can only draw 100 amps tops if you are considering only 240 volt loads. Remember that a 100 amp panel can only deliver 24000 watts (VA) maximum whether you are considering 240 v or 120 v loads. So it follows that 240 volts X 100 amps = 24000 VA (watts) or 120 volts X 200 amps = 24000 VA with 100 amps on each hot leg.

A 200 amp panel, on the other hand, can deliver 48000 VA. 200 amps if all loads are 240 volts, 400 amps if all loads are 120 volts equally divided between legs, 200 amps per leg.

So you see, there IS a big difference between a 100 amp and 200 amp panel.

The best way to get a handle on what kind of a panel you need is to figure out the kind of power in VA that your house is likely to need now and in the future and proceed accordingly. As you can see from above, considering amperage alone can potentially be somewhat misleading as there is typically a mix of 240 volt and 120 volt circuits in a panel.

Wg, bwetzel, you guys were right about the 120 volt circuits. I was too much into thinking in terms of the overall 240 volt picture only. Boy! crow tastes kind of bad! Eating my hat doesn't sound too appealing either.

 

P.S.

Terry,

My last post crossed with Wgoodrichs, he pretty much said it all in his post above my last one.

Spike

 

Spike you gain one heck of a lot of respect in this forum when you speak your mind and expect opposing speakers to prove their point. YOu gain the most respect from those in this forum when you have a stonge enough inner strenght to correct what you have discovered yourself to be wrong. You did both admirably. You were open to input from the opposing speach yet held strong until you knew you were wrong in your thinking. Then you came back in and posted a corrective statement confirming what you now believe is right. This is not a contest of who is better or bigger than the other. This forum is a search for what is right and true intent according to physics and the NEC rules. Sometimes that true intent is hard to agree on. Then we have to agree not to agree. That has happened many times in this forum. Many more times we have discovered each one of off base in our thinking or interpretations. Not one person in this form replyig has been without discovering something they thought that turned out something entirely different.

YOU DIDN'T EAT CROW, You did what you believe is right and stood up and said so. For that I commend you much !

Congrats you learned something same as we all have in this forum.

Keep up your good work it is obvious you care.

Wg