Equi=Core Hum & Other Issues
@jea48 I wanted you to see the new installation. And I was wrong about conduit; code does not require it. https://ibb.co/tzhyY6B No more transformer hum. |
@ lowrider57 Glad to hear the new electrical service solved your hum problem. As for the service entrance cable the electrical contractor installed. Yes, it meets NEC, Article 338 of the code. And it is obviously approved for use by the AHJ (Authority Having Jurisdiction) in your area. The AHJ has the final say. In the Capital City, metro, and surrounding suburbs cities in my State conduit is required for the electrical service. I’m not sure if any counties or cities in my state allows service entrance cable use for an electrical service. Though I do not know that for a fact. Jim |
I decided to install a whole house surge protector; a Square D to mate with my new service panel. https://www.amazon.com/dp/B00CONA1OQ/ref=cm_sw_r_other_apa_i_x2a.EbGRB0EEQ The instructions state that a 2-pole 20 amp breaker is required. OK, fine. Now here's what I don't understand; if the surge protector has its own breaker wired to hot, neutral, ground on both phases, how is it going to absorb a spike before other circuits? Won't a surge trip other breakers as well as the surge protector? There is no point of least resistance. @jea48 Feel free to comment. |
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lowrider57 The instructions state that a 2-pole 20 amp breaker is required. OK, fine. The SPD protects the whole electrical panel from high voltage transient surges/spikes. The Square D SPD uses multiple MOVs to protect the panel from high voltage surges/spikes transients. During a high voltage transient surge/spike event the MOVs limits the high voltage and absorbs or diverts the high current to ground. That is why the electrical service entrance neutral conductor connection to earth is so important. (The Grounding Electrode System.) The lower the grounding electrode resistance to earth soil the better. (Grounding electrode? Ground rod/s, metal main incoming water service piping, foundation footing concrete encased rebar.) IEEE recommends 5 ohms or less. It is very important where the electrician mounts, installs, the SPD to the outside of the electrical panel enclosure. (Do not install the SPD inside the panel.) Make sure he installs the 2 pole breaker for the SPD wire connections in the first two spaces below, near, the panel’s main breaker. Doesn’t mater which side just so it is in breaker spaces 1, 3 or 2, 4. The electrician more than likely will have to relocate a circuit/s load breaker/s to make room for the SPD 2 pole breaker. I would relocate the lighter load circuit/s breaker/s. The SPD connection wires must be kept short as possible without any sharp bends in the wires. Square D HEPD50/HEPD80 SPD user guide and installation NOTE:To enhance the performance of the HEPD50/HEPD80, twist and keep the conductor length as short as possible by trimming down the wires (do not loop or coil the wires and avoid sharp bends). Always connect the HEPD to the circuit breaker(s) found in the closest proximity. Increasing the HEPD conductor length will degrade its performance.https://download.schneider-electric.com/files?p_enDocType=User+guide&p_File_Name=NVE82551.pdf&am... See page 4 and page 6, figure #3. Why is keeping wires short so important? Here is a great video on the why. https://www.youtube.com/watch?v=5Wb79cXmSlc I attended a seminar a couple of years ago and seen the demonstration first hand. Inches do matter. Going from memory don’t you also have a sub panel for your audio equipment? If yes you should install an SPD on that panel as well. For added protection of your audio equipment a Type 3 SPD should be installed to plug your audio equipment into. Make sure it has a minimum 1449 3rd edition listing. Newer Type 3 SPDs may have a 1449 4th edition listing. (Read the specs wording carefully. Minimum 1449 3rd edition listed). Jim. |
@jea48 That's all great information; the position of the SPD relative to the main breaker and how using short wiring will clamp surge voltage. There are plenty of knock-outs available to do this correctly. Your explanation of having a low grounding electrode resistance to earth helps me understand the entire concept. Now, regarding the subpanel, why is a SPD needed? Wouldn't a surge be clamped by the SPD on the main panel? As always, I appreciate your thoughtful comments. |
