4 ms·

A few years ago I had to wire a generator up to a distribution warehouse so that goods could still be shipped in event of a power loss. The actual wiring proces

A few years ago I had to wire a generator up to a distribution warehouse so that goods could still be shipped in event of a power loss. The actual wiring process wasn't too difficult (have a properly licensed electrician do it. NO EXCEPTIONS!) but the process of wiring it up to the building natural gas we hit a snag. We had a 25kW generator spec'd but using natural gas required more pressure than the utility could supply. We switched to propane (which is less efficient) and used building gas as a last-ditch failover (if I recall correctly it only had enough pressure to supply half load or something). Note that disel and plain old gasoline generators push out really noisy power. Do not hook up electronics to gas generators without a line conditioner or UPS in the middle (and the UPS will probably complain about voltage sags and/or lack of grounding). If you're going to make it a permanent fixture to your home that you can actually rely upon, you really ought to make it run on natural gas and/or propane (as a failover). Quieter, cheaper, and less likely to be a shortage (most homes without power in NY/NJ still have natural gas and a modestly sized propane tank could run our generator for a whole week at full load, and we had contracts with multiple firms to bring propane). Also, make sure you test and condition the generator periodically, as any oil-lubricated engine left idle will eventually freeze up. Finally, you want to oversize the generator just a touch, as running them at 100% is a great way to burn it out relatively quickly. If you can keep it at about 80%, it'll increase the longevity of the unit, and also give you some fudge factor.

ars 14y ago
> The actual wiring process wasn't too difficult (have a properly licensed electrician do it. NO EXCEPTIONS!) Why no exceptions? This isn't really that hard to do, as long as your have some knowledge, and you researched in advance what to do. Obviously if you are unsure of your skill and/or knowledge level don't do it. But you don't have to be licensed to know what to do.
- MattRogish 14y ago
  Because if you do it wrong and kill someone or burn your house down or any of the other innumerable bad things a 5+kW combustion engine device can do, it's your fault, and your insurance may not even cover it (not to mention any legal issues). Having a properly licensed/bonded electrician do it, generally, will keep the liability out of your hands. Given how cheap it was for the actual labor, I'm not comfortable taking that risk. YMMV.
  - ars 14y ago
    Do you know how many things you can do wrong and kill someone? This is way down on the list. Hire someone if you want, but don't tell people "no exceptions" there are plenty of quite handy people who would have no trouble doing this properly. Like you said: It's not really that hard.
    - oconnore 14y ago
      Those people also know enough (or know too little) to ignore advice on the internet. For everyone else, disclaimers are good.
- andrewaylett 14y ago
  I suspect because at some level of awareness you think you know enough, but have yet to discover what you don't know, which means you're actually much less safe than someone with a bit more awareness who knows enough to leave well alone. There have been plenty of discussions on HN about this phenomenon, but I can't remember what it's called.
  - ars 14y ago
    All true - except electrical work for a home is really not that hard.
    - Freestyler_3 14y ago
      For some it isn't I agree. -Also I advice do not plug in in an outlet via male to male. Reason: if your peak is over 5kw/h, the wiring might not handle that! See the 48kw/h wiring of yours is the calculation of the total amount each breaker can have. I don't know US breakers but lets say it is 120v/40A per breaker, you have 10 breakers. But if you connect your generator on the outlet on one breaker the electricity has to travel through one specific pair of wires all the time (from outlet to wire intersection spread from there)
      - mindslight 14y ago
        FWIW, the common receptacle in the US is rated at 15A, on a 15A or 20A breaker. You'd just end up limiting your max power to the capacity of that one circuit, and overloading would trip the breaker on the circuit you were using to backfeed. Technically if you were putting 20A into a 15A receptacle on a 20A circuit you'd be overloading it, but the same thing can happen when drawing power and such circuits are still condoned. Also technically you should only consider that circuit sufficient if you aren't planning on having a continuous load greater than 12/16A, but people generally don't pay attention to that rating either.
        Freestyler_3 14y ago
        if your energy supplier is behind the breaker then the breaker only trips if you use all your power on other breakers. but if you use some devices on the breaker of the supplying device then that is not taken into the calculation. I forgot to state clearly that you would be limited to the maximum of that one breaker, which is inconvenient if your usage is above it sometimes.
- rdl 14y ago
  I'm not a licensed electrician in any jurisdiction, but I've done work on single and three phase systems in multiple countries, plus LVDC stuff. I mainly learned from usenet FAQs and then from reading books and talking to electricians. Usually you can do your own work and then get a licensed/bonded electrician to sign off on it, even in the US. I can't do work for hire (due to licensing...), but pretty much anything short of medium voltage I'd feel comfortable DIY. It is not rocket science. There are some tricks in actually running cable in older buildings, and how stuff is wired most commonly, which are worth learning hands-on, but everything else is fairly simple theory and can be learned from reading.

ars 14y ago

> The actual wiring process wasn't too difficult (have a properly licensed electrician do it. NO EXCEPTIONS!) Why no exceptions? This isn't really that hard to do, as long as your have some knowledge, and you researched in advance what to do. Obviously if you are unsure of your skill and/or knowledge level don't do it. But you don't have to be licensed to know what to do.

MattRogish 14y ago
Because if you do it wrong and kill someone or burn your house down or any of the other innumerable bad things a 5+kW combustion engine device can do, it's your fault, and your insurance may not even cover it (not to mention any legal issues). Having a properly licensed/bonded electrician do it, generally, will keep the liability out of your hands. Given how cheap it was for the actual labor, I'm not comfortable taking that risk. YMMV.
- ars 14y ago
  Do you know how many things you can do wrong and kill someone? This is way down on the list. Hire someone if you want, but don't tell people "no exceptions" there are plenty of quite handy people who would have no trouble doing this properly. Like you said: It's not really that hard.
  - oconnore 14y ago
    Those people also know enough (or know too little) to ignore advice on the internet. For everyone else, disclaimers are good.
andrewaylett 14y ago
I suspect because at some level of awareness you think you know enough, but have yet to discover what you don't know, which means you're actually much less safe than someone with a bit more awareness who knows enough to leave well alone. There have been plenty of discussions on HN about this phenomenon, but I can't remember what it's called.
- ars 14y ago
  All true - except electrical work for a home is really not that hard.
  - Freestyler_3 14y ago
    For some it isn't I agree. -Also I advice do not plug in in an outlet via male to male. Reason: if your peak is over 5kw/h, the wiring might not handle that! See the 48kw/h wiring of yours is the calculation of the total amount each breaker can have. I don't know US breakers but lets say it is 120v/40A per breaker, you have 10 breakers. But if you connect your generator on the outlet on one breaker the electricity has to travel through one specific pair of wires all the time (from outlet to wire intersection spread from there)
    - mindslight 14y ago
      FWIW, the common receptacle in the US is rated at 15A, on a 15A or 20A breaker. You'd just end up limiting your max power to the capacity of that one circuit, and overloading would trip the breaker on the circuit you were using to backfeed. Technically if you were putting 20A into a 15A receptacle on a 20A circuit you'd be overloading it, but the same thing can happen when drawing power and such circuits are still condoned. Also technically you should only consider that circuit sufficient if you aren't planning on having a continuous load greater than 12/16A, but people generally don't pay attention to that rating either.
      - Freestyler_3 14y ago
        if your energy supplier is behind the breaker then the breaker only trips if you use all your power on other breakers. but if you use some devices on the breaker of the supplying device then that is not taken into the calculation. I forgot to state clearly that you would be limited to the maximum of that one breaker, which is inconvenient if your usage is above it sometimes.
rdl 14y ago
I'm not a licensed electrician in any jurisdiction, but I've done work on single and three phase systems in multiple countries, plus LVDC stuff. I mainly learned from usenet FAQs and then from reading books and talking to electricians. Usually you can do your own work and then get a licensed/bonded electrician to sign off on it, even in the US. I can't do work for hire (due to licensing...), but pretty much anything short of medium voltage I'd feel comfortable DIY. It is not rocket science. There are some tricks in actually running cable in older buildings, and how stuff is wired most commonly, which are worth learning hands-on, but everything else is fairly simple theory and can be learned from reading.