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  1. #1
    Ed Martino's Avatar
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    Default How much is to much?

    Came across a 200 amp challenger panel in a home that does not have gas service to it. All appliances are electric there’s’ a heat pump, stove, dryer, freezer in the utility room and a Jacuzzi on the back porch. “Somebody” installed a sub-panel for the heat pump using a 100 amp breaker in the main panel. So there is a 200 amp panel (service cable is 4/0awg) with a 100 amp, 50 amp, 40 amp, 3-30 amp, 3-20 amp. 7-15 amp. The potential is everything can be operating at the same time.

    So How Much is To Much?

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    Default Re: How much is to much?

    The only true way is to perform a demand load calculation. Adding up the breaker ratings is meaninless as it does not take into account load diversity or the fact that most circuits will be drawing nowhere near the maximum breaker rating.


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    Default Re: How much is to much?

    Quote Originally Posted by Ed Martino View Post
    So How Much is To Much?
    If you mean how much is too large of a service, well, I would like to have a 1,200 amp service to my house, and all the toys which that would power ... ... but I don't .

    How much is to much? Depends on the depth of one's pocketbook, I guess.

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    Default Re: How much is to much?

    I've gone down the road you are several times and am always amazed at how much equipment a 200A service can support and be within the limits of a load calc.

    Sure, everything "could" be on at the same time.... but it won't. Every car on the road "could" be on the same road at the same time but they aren't. People are unlikely to cook a turkey dinner, do laundry, run the heat pump, sauna and every light in the house. These things are all factored into a load calculation and how electrical services are generally sized for houses.

    From an HI's standpoint the best thing you can do if it looks overloaded is recommend a load calculation.... along with looking at the panel "someone" installed


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    Default Re: How much is to much?

    Since you're info out on the web claims you're an instructor of some sort on HIs, I'm assuming you're referring to other than demand load calculations.

    Depends on the listed labeling, limitations, and wiring diagram of the panel and its vintage, and the vintage of the breakers installed within.

    For example 125 amp or less breaker might be listed 75C, 75/60C or 60C.

    Older breakers may or may not be of the type rated for the heat pump supply.

    For example the buss ratings and stab ratings, and how/what/where what has been installed within same (minis, wafers, tandems, quads, etc.), and in what position in the panel.

    Without pictures, a diagram, a model number, the indicated limitations (labeling) etc. can't say.

    For example some panels may have a limitation to say a 60C 70 amp breaker max on the bus, so without knowing what the listed schedule and limitations are - the presence of even one such breaker exceeding that limitation may in and of itself be "too much", even if that was all that was in the panel! As I recall a thread not too long ago, Roger Frazee started on the subject (after another vintage branded panel had labeled 70 amp bus stab rating limits) he shared some good explanitory material from a major manufacturer on the subject (Sq. D, IIRC). He also made mention of a 200 A Challenger Panel he once owned or employed with a 125 A buss stab limitation. (One of the threads can be seen here, clickable link: http://www.inspectionnews.net/home_i...tml#post143588 ) So I mention that, also because the temperature ratings of breakers at 125A or less are not necessarily okay to use at 60C Temperature limitations or 75C, it depends on the markings/listings. And since we don't know if the panel is indoors or outdoors we do not know the temperature limitations for the equipment to the remote panel for the HP either. Also curious, AFAIK S. NJ offers programs for cycled demand discounts for AC and/or HP during summer months and it would not be uncommon to have in place - such a POCO controlled demand cycling unit on the HP unless the occupant had to opt out of such a discount program due to a health complication, etc.

    Seems a circuit or two shy in the 20 amp category (Laundry receptacle circuit? Outside front/back, service for HP, receptacles? Garage receptacle(s)?). Guessing this property has muni water & sewer, no well pump, no lifter pumps, No sump/foundation pumps (rare for S. NJ). Sure no burried oil tanks?

    Last edited by H.G. Watson, Sr.; 01-01-2011 at 06:21 AM.

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    Default Re: How much is to much?

    Quote Originally Posted by Jim Port View Post
    The only true way is to perform a demand load calculation. Adding up the breaker ratings is meaninless as it does not take into account load diversity or the fact that most circuits will be drawing nowhere near the maximum breaker rating.
    Not necessarily meaningless as pertaining to buss rating limitations and stab rating limitiations.

    Depends on the labeling, wiring diagram and listing for the panel.

    Equipment temperature ratings also need be considered. See post above, and this thread:

    http://www.inspectionnews.net/home_i...tml#post143588


  7. #7
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    Default Re: How much is to much?

    One can speculate all manner of other issues that might possibly exist, but that does not take away from one simple fact:

    The sum of the individual breakers is not referenced anywhere in performing load calculations. Adding breakers has as much relevance as Swahili rules of grammar.

    So, to answer the question 'how much is too much,' there is no answer. It's the wrong question to ask. It's like trying to answer 'how long is a rope.'

    The question to ask is: Is the service large enough to support the loads? To answer that question, a load calculation must be done.

    To do such an evaluation is beyond the scope of a home inspection, and should be done only by a licensed electrical contractor or professional engineer. If you can't sign the plans, your calculations are meaningless.


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    Default Re: How much is to much?

    Quote Originally Posted by Ed Martino View Post
    Came across a 200 amp challenger panel in a home that does not have gas service to it. All appliances are electric there’s’ a heat pump, stove, dryer, freezer in the utility room and a Jacuzzi on the back porch. “Somebody” installed a sub-panel for the heat pump using a 100 amp breaker in the main panel. So there is a 200 amp panel (service cable is 4/0awg) with a 100 amp, 50 amp, 40 amp, 3-30 amp, 3-20 amp. 7-15 amp. The potential is everything can be operating at the same time.

    So How Much is To Much?
    Arghh! one more thing occurs to me.

    Don't know how rural this installation may be, or age of home for that matter (figuring at least 20+ years even if old shelf stock equipment was used) but if I'm recalling correctly, I'm remembering an investigation or review/consult years ago, finding POCO "point of service" actually on "customer owned" pole then dropped to residence in Central south New Jersey (I'm remembering encountering this in Cumberland Co I'm thinking, perhaps Deerfield or Stow Crreek, its been a long while ago). Am dubious/curious about "service cable" description, 4/0 (AL? CU?) and non-descript 200 amp descript panel (mains, mlo, service equip?) as unclear if main power panel or actual service equipment even on a free-standing single family home if rural area in So. NJ. Got more interesting if entrance was adjacent to what was once location of pre-existing burried oil tank as far as electrodes bonding, and the IIRC areas of sandy loamy soils and brackish/tidal areas.


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    Default Re: How much is to much?

    Why are you so fixated on demand load calculations J.S.? The OP hasn't indicated that was any part of his question, Jim P simply responded as though that was the presumed intent of the OP's question/statement.

    Buss ratings, stab ratings and limitations of the panel are relevant, and DO involve adding the protection rating of the breakers installed adjacent depending on the buss configuration in determining if that limitation has been reached or exceeded.

    4/0 unknown material 200 (?) amps unknown split buss or mains or mlo panel. All we know is a challenger panel is IN the home, no mention of it being THE point of service, or "service equipment" or what type of panel or vintage it is; in fact in rural areas S. NJ, I'd think it just as likely as not to be service equipment irrespective of what type of cable or conductor is feeding it or if in metallic conduit, or whatever.

    The OP is in NJ, remember, the home of the only FPE/Reliance lawsuit and settlement (circa about the time Challenger/Sylvania/Westinghouse was no longer the same "Challenger") with lots of local hardware stores that still stock old "new" inventory, even today!.

    W/O pictures and/or clarifications and certainly alot of assumptions as to what he is or is not saying/asking about, we don't really know what the OP has or is asking or why, now do we?

    Total buss connection labeled limitations have nothing to do with load calculations. They are a case where adding the rated circuit breakers attached compared to the limitations of the panel are done (non ctl), as are buss stab limitations in older panels.

    See: http://www.inspectionnews.net/home_i...eck-panel.html

    We don't know if said challenger is a zinsco type /sylvania style or westinghouse C or later post westinghouse redesign challenger brand type either.

    Frankly I'm dubious about vintage panel not made for decades, adequacy of equipotential zone for "jacuzzi", proper and adequate GFCI (NOT GFPE) protection, adequacy of grounding, bonding, etc. and safe zone for/from Heat Pump system and equipment in lightning prone /coastal S. NJ. IMpastE Not a region "known" for compliance with safety issues/levels even at the standards in effect at time work was done, let alone maintenance of same, or "safety upgrades", decades later.

    Last edited by H.G. Watson, Sr.; 01-01-2011 at 08:52 AM.

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    Default Re: How much is to much?

    While this question could have been worded more clearly as to the true intent, 4 out of 5 took it to be a question about the ability to power all that equipment from a 200 amp service. Performing a demand load calculation is the only way to determine the proper size. The way I took the OP was that they felt that too much demand was being placed on the available service based on the quantity and values of the breaker handles.


  11. #11
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    Default Re: How much is to much?

    Thank you all for the imput.
    The home is a standard South Jersey track home built 1986-87. Slab construction, under ground electric service, no well or sump. The 4/0amg is aluminum. Load calc is recommended because the last inspeciton sticker is the final in 1987.

    I'll try to insert a photo. But need to figue out how to reduce size.


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    Default Re: How much is to much?

    Quote Originally Posted by Jim Port View Post
    Performing a demand load calculation is the only way to determine the proper size. The way I took the OP was that they felt that too much demand was being placed on the available service based on the quantity and values of the breaker handles.
    The question I have, or maybe I missed the answer in the other posts above (even after re-reading them again) is ... why do a load calculation? ... why be concerned about a load calculation? ... no evidence was presented to us indicating in any way that there is or has been a problem with the electrical service as currently configured.

    Yes, I took the 'out-of-the-box' route by seeking clarification as to what the original intent of the question was (the only 1 out of 5 to do so) - frequently we are presented with incomplete information and only at the end of a long debate does the information come forth which would have provided for a short answer.

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  13. #13
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    Default Re: How much is to much?

    If you have a standard all-electric house with no more than two heat pumps a 200 amp service should be fine. Non-standard loads like a wood shop or machine shop would require additional scrutiny.


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    Default Re: How much is to much?

    Quote Originally Posted by John Steinke View Post
    The question to ask is: Is the service large enough to support the loads? To answer that question, a load calculation must be done.

    I completely agree John.

    While the panel buss-bars and components are important I don't understand why anyone would approach that question with this response (HG). It's a given you would not have a 200 amp service (and main breaker) feeding a panel LISTED and rated at 100 amps. There is no need to discuss the buss ratings as that's already taken care of as part of the panel Listing.

    I think the original question has more to do with "is bigger better ? and is there such a thing as too big?" In which case I think JP's response is also correct... there is no such thing as too big. It's limited to what the power Co. is prepared to provide or what the ahj limits, if at all (ie: you probably can't get a 800 amp 3 phase service in most residential neighborhoods).

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    Default Re: How much is to much?

    I have a question. If you turn on everything in the house and clamp the line side feed, wont that say how much load is imposed/drawn?
    (if this is a stupid question, I dont want to know)

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    Default Re: How much is to much?

    Quote Originally Posted by Marc M View Post
    I have a question. If you turn on everything in the house and clamp the line side feed, wont that say how much load is imposed/drawn?
    (if this is a stupid question, I dont want to know)
    Not a stupid question at all. If you do as you suggested, (assuming you activated all strip heat in heat pumps), All stove,oven elements, remembered to run enough hot water to start the water heater, etc... Your load could very well be above the 200 amp rating(or the rating originally calculated). The NEC allows for derations in the service calculations. This is simply because everything does not always run all at once, there are load cycles on the service.


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    Default Re: How much is to much?

    Just wait...others still need to chime-in.
    I do appreciate your answer, I was told by an electrician to add both legs together. I suppose the 240's can throw off the balance but it is residential, however.

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    Default Re: How much is to much?

    Quote Originally Posted by Marc M View Post
    I was told by an electrician to add both legs together.
    If there are any 240 volt loads (and there will be - unless the house only has an old 120 volt service) then adding the two legs together gives an erroneously high total as the same current is flowing through both legs, not twice the current.

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    Default Re: How much is to much?

    Quote Originally Posted by Marc M View Post
    Just wait...others still need to chime-in.
    I do appreciate your answer, I was told by an electrician to add both legs together. I suppose the 240's can throw off the balance but it is residential, however.

    Actually the 120V loads will be the ones that throw the balance off. A 240V load is balanced. As stated earlier, the current in a 240V load will never be in both legs at the same time.(180 degrees difference)


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    Default Re: How much is to much?

    Quote Originally Posted by Jerry Peck View Post
    If there are any 240 volt loads (and there will be - unless the house only has an old 120 volt service) then adding the two legs together gives an erroneously high total as the same current is flowing through both legs, not twice the current.
    WHAT?!?


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    Default Re: How much is to much?

    Quote Originally Posted by Marc M View Post
    I have a question. If you turn on everything in the house and clamp the line side feed, wont that say how much load is imposed/drawn?
    (if this is a stupid question, I dont want to know)
    Not all loads are resistive. Not all services are 120/240.


    Utility programs may have high demand discount program addressable devices to cycle the cooling equipment for example.

    Depends a bit on who is "you", and who is "that".


    But not looking to derail the thread, Marc. Could start your own?

    1987 CofO challenger electric equipment likely mfg previously, therefore not likely to be of the style most are familiar with.

    Westinghouse didn't acquire Challenger Electric until after this installation.

    Last edited by H.G. Watson, Sr.; 01-03-2011 at 10:12 AM.

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    Default Re: How much is to much?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    WHAT?!?
    I could explain it to you, but you would not understand.

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    Default Re: How much is to much?

    Quote Originally Posted by H.G. Watson, Sr. View Post
    Not all loads are resistive. Not all services are 120/240.


    Utility programs may have high demand discount program addressable devices to cycle the cooling equipment for example.

    Depends a bit on who is "you", and who is "that".


    But not looking to derail the thread, Marc. Could start your own?

    1987 CofO challenger electric equipment likely mfg previously, therefore not likely to be of the style most are familiar with.

    Westinghouse didn't acquire Challenger Electric until after this installation.
    Yea, sorry ED, didnt mean to Bogart your thread.

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    Default Re: How much is to much?

    1987.

    I'm hard pressed to recall a PRE-Westinghouse Challenger Electric Residential MCB Load Center/L&AB panel that allowed a 100 Amp breaker below the main and a 200 A MCB to be used as service equipment.

    Show me the panel labeling, wiring diagram, and listing/use specifications marked on the panel. Look forward to the photos.

    You can open your larger photo in just about any photo edit or even "paint", re-size and save in a smaller jpg, bmp, etc. format. Its quite easy. You can also post your larger photos elsewhere on the web, for example any of the multitude of free photo hosting sites, set your permissions for the "album" and photos to be "public" and post a link to same here.

    Last edited by H.G. Watson, Sr.; 01-04-2011 at 08:48 AM.

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