Electrician Talk

8 thoughts on “Electrician Talk”

  1. Fuse/Breaker/Surge Suppressor on a ground wire?

    I was pondering the possibility of an extremely close lightning strike turning the grounding wire into a backdoor path for a catastrophic surge to wreak havoc on sensitive electronics. Was considering addressing both incoming hot lines with commercial grade surge suppressors (in addition to fuses/breakers), but that grounding wire seems to just sit there like an open highway for rogue electrons, unchecked except for going through an inexpensive (relatively speaking) consumer level surge suppressor/UPS which does little to boost my confidence. I realize all bets are off for a direct strike in the high volt high amp world of lightning, but shy of a direct strike is placing anything along the ground line a viable option to reduce risk?

    • If all you have is a plug-in type UPS with a surge suppressor built-in then you need to get a separate surge suppressor placed in parallel to your incoming feeder wires. It should be connected somewhere between your meter-base load-side screws and your main electrical service main-breaker line taps (screws). The reason for this needed placement location is to absorb any incoming or outgoing surges. Another safety tip I always tell customers is to connect a extra 8ft ground rod 12ft from your existing ground rod. Always run same size and type of existing grounding wire for that extra ground rod.

      • I was considering a separate single-line commercial grade surge suppressor on each line entering/exiting the structure (rated at just over 50K Amps, 15 events) along with inline fuses/circuit breakers. Placed downstream to this would be a commercial grade 240V UPS/Surge suppressor. At the point of use would be the more typical small consumer level UPS/Suppressors as a last ditch layer of protection.

        The big question I have is what sort of issues does putting suppressors & fuses on the grounding line create? Would putting a suppressor and/or a large (4K to 6K Amp) fuse along the ground line defeat the safety purpose of that line if there were to be a legit short/fault somewhere that needed to be redirrected to ground? (I’m thinking a large fuse that would blow at extreme energies but would keep the line intact for diffusing any potential faults & shorts)

        • Every engineer have their own version of Lightning protection design. I have been known to be right more so than engineers when it comes to understanding the designing of what lightning protection needs. My military, private electrical education and field training together is the key to my understanding. Most non-self-employed electrical engineers have no field training to speck of just classroom theory when the subject is on industrial grounding systems.
          Here is my take, in order for a structure or the contents of the structure not be damaged by stray high-voltage surges or the drainage of stray voltage surges not drain at a decent speed causing more damage a premium lightning protection grid has to installed. The material needed would be thousands of feet of continuously unbroken #4-solid-tin-coated-bare-copper. If splicing is needed a gun-powder fired Exothermic weld must be done. All wire and connections must be buried in 8 feet or more of dirt. Most all industrial ground systems like this would be used to protect very high erected steel towers or large buildings. This underground looping system may be a series of independent loops tied together by Exothermic weld. This type of surge suppressor protection of large buildings are the most efficient way to do lightning protection. If a couple of computers need protection in a small building then a simple 220 volt surge arrester connected in parallel of main breaker in main service panel would be the most economical.

          As far as using anything other than what has been discussed here I would not use. Ground loop method is the best but has to be engineered.

  2. Here is my system layout:
    Residential home.
    400 amp service entrance with twin 200 amp panels. Neutral bonded to ground

    A 60 amp 240 volt breaker at the service panel feeding a sub panel at the well pump building.

    The well pump building is separate from the home by 180 feet away.

    This was done under the code back in 1994.

    So we have three wires for the sub feed cable underground in 2 inch PVC conduit,
    2 gauge Aluminum / hot hot neutral.

    At the well pump building we have:
    100 amp sub panel with 60amp 240 volt mains breaker disconnect.
    Separate neutral and grounds buss bars with no bonding of neutral to ground.
    two ground rods 6 feet apart hooked to the ground buss bar
    A 20 amp 240 volt breaker to the well pump
    Several 120 volt breakers for lighting and receptacles
    A 50 Amp 240 Volt breaker wired to a
    NEMA 14-50 3 pole 4 wire 50 Amp receptacle used as an RV land line hookup connection.
    There will be a 50 foot RV type power extension cord (8 gauge copper)
    connecting the well house sub panel to a cargo trailer sub panel using
    NEMA 14-50 3 pole 4 wire 40 Amp 250 Volt plugs and receptacles
    hot hot neutral ground
    The Cargo trailer has a 100 amp sub panel with no mains several breakers for 120 volt lighting and receptacles
    one 50 amp 240 volt breaker wired to a
    NEMA 6-50 2 pole 3 wire receptacle / hot hot ground / to be used for a welder in in the trailer.
    No specs on the welder have not purchased yet.
    Of course the cargo trailer is considered a temporary or intermittent connection.

    Question 1:
    Do I need to supply two ground rods at the cargo trailer for the sub panel
    and hook them up each time I park it there or will the four wire power line be all that is required by code?
    Question 2:
    At 180 feet from the service entrance with the 2 gauge aluminum sub feed
    and the 50 foot 6 gauge RV extension cord should I de-rate the 50 amp
    welder breaker at the cargo trailer?
    thank you for your help.

  3. I am installing a new light fixture. The light itself has two white wires and a green ground wire.

    The electrical box has
    – two white wires tied together
    – two black wires tied together
    – one red wire

    Note that this light is connected to a dimmer. Additionally, I am in a condo and the electrical is attached to a system where if you wire something wrong or there is an electrical issue, an alarm in the condo unit goes off. Not sure if these points impact the wiring that is there.

    I would like to know how to install the light. When I took off the old light. Both wires of the light were connected to the red wire (that’s it, it was not even grounded).
    Thanks for the help!

Leave a Comment