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Author Topic: Question about copper braid for grounding  (Read 698 times)

W9IQ

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Re: Question about copper braid for grounding
« Reply #30 on: October 20, 2020, 12:25:47 PM »

As a ham you should know and follow electrical codes as it pertains to the hobby. Code requires you to bond the coax and radio chassis to ground using a 6 AWG conductor all the way back to the AC Service Ground, the exact same place the #14 AWG green wire ground in the AC power cord and your house wiring go too.

This is overstated. The operating grounding conductor that connects to the back of equipment can be 14 AWG or an equivalent braid or strap [ref.  810.58(C)]. The conductor from a mast, coax or antenna to the GEC can be 10 AWG (if the lead-in conductor is the same or smaller) [ref 810.58(B)].

- Glenn W9IQ
« Last Edit: October 20, 2020, 12:39:10 PM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

AA4PB

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Re: Question about copper braid for grounding
« Reply #31 on: October 20, 2020, 01:35:10 PM »

Actually, the NEC says two things. 1) The coax shield must be grounded near the point where it enters the building and 2) where a building has two or more independent grounding systems you must bond the systems together with a #6 or larger conductor.

No where does it say that you must run a #6 wire from the back of your radio to the electrical system ground.
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Bob  AA4PB
Garrisonville, VA

W9IQ

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Re: Question about copper braid for grounding
« Reply #32 on: October 20, 2020, 02:26:22 PM »

As I mentioned, it does say that the wire from the chassis must be 14 gauge (equivalent) or larger.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KF5LJW

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Re: Question about copper braid for grounding
« Reply #33 on: October 24, 2020, 09:41:27 AM »

This is overstated. The operating grounding conductor that connects to the back of equipment can be 14 AWG or an equivalent braid or strap [ref.  810.58(C)]. The conductor from a mast, coax or antenna to the GEC can be 10 AWG (if the lead-in conductor is the same or smaller) [ref 810.58(B)].W9IQ
Wrong again Glen, when aRE YOU GOING TOP LEAR.
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KF5LJW

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Re: Question about copper braid for grounding
« Reply #34 on: October 24, 2020, 10:50:38 AM »

AA4PB and W9IQ both need to read the right code sections. Article 810 is for Antenna Systems, not DC Equipment Power and Grounding. If they would read NEC 250 VIII. Direct-Current Systems would know the difference between an antenna system and DC power system. Perhaps they do not care to know or admit it, but the rest of you might like the facts.

VIII. Direct-Current Systems

250.160 General. Direct-current systems shall comply
with Part VIII and other sections of Article 250 not specifically
intended for ac systems.

250.162 Direct-Current Circuits and Systems to Be
Grounded.
Direct-current circuits and systems shall be
grounded as provided for in 250.162(A) and (B).
(A) Two-Wire, Direct-Current Systems. A 2-wire, dc system
supplying premises wiring and operating at greater than
50 volts but not greater than 300 volts shall be grounded.

Exception No. 1: A system equipped with a ground detector
and supplying only industrial equipment in limited areas
shall not be required to be grounded.

Exception No. 2: A rectifier-derived dc system supplied
from an ac system complying with 250.20 shall not be required
to be grounded.

Exception No. 3: Direct-current fire alarm circuits having
a maximum current of 0.030 ampere as specified in Article
760, Part III, shall not be required to be grounded.

(B) Three-Wire, Direct-Current Systems. The neutral
conductor of all 3-wire, dc systems supplying premises wiring
shall be grounded.

250.164 Point of Connection for Direct-Current Systems.

(A) Off-Premises Source. Direct-current systems to be
grounded and supplied from an off-premises source shall
have the grounding connection made at one or more supply
stations. A grounding connection shall not be made at individual
services or at any point on the premises wiring.

(B) On-Premises Source. Where the dc system source is
located on the premises, a grounding connection shall be
made at one of the following:
(1) The source
(2) The first system disconnection means or overcurrent
device

(3) By other means that accomplish equivalent system protection
and that utilize equipment listed and identified
for the use

250.166 Size of the Direct-Current Grounding Electrode
Conductor.
The size of the grounding electrode conductor
for a dc system shall be as specified in 250.166(A)
and (B), except as permitted by 250.166(C) through (E).
(A) Not Smaller Than the Neutral Conductor. Where the
dc system consists of a 3-wire balancer set or a balancer winding
with overcurrent protection as provided in 445.12(D), the
grounding electrode conductor shall not be smaller than the
neutral conductor and not smaller than 8 AWG copper or 6
AWG aluminum.

(B) Not Smaller Than the Largest Conductor.[/b] Where the
dc system is other than as in 250.166(A), the grounding
electrode conductor shall not be smaller than the largest
conductor supplied by the system, and not smaller than 8
AWG copper or 6 AWG aluminum.

(C) Connected to Rod, Pipe, or Plate Electrodes. Where
connected to rod, pipe, or plate electrodes as in 250.52(A)(5)
or (A)(7), that portion of the grounding electrode conductor
that is the sole connection to the grounding electrode shall not
be required to be larger than 6 AWG copper wire or 4 AWG
aluminum wire.

(D) Connected to a Concrete-Encased Electrode. Where
connected to a concrete-encased electrode as in 250.52(A)(3),
that portion of the grounding electrode conductor that is the
sole connection to the grounding electrode shall not be required
to be larger than 4 AWG copper wire.

(E) Connected to a Ground Ring
. Where connected to a
ground ring as in 250.52(A)(4), that portion of the grounding
electrode conductor that is the sole connection to the
grounding electrode shall not be required to be larger than
the conductor used for the ground ring.

250.168 Direct-Current System Bonding Jumper. For
direct-current systems that are to be grounded, an unspliced
bonding jumper shall be used to connect the equipment
grounding conductor(s) to the grounded conductor at the
source or the first system disconnecting means where the
system is grounded. The size of the bonding jumper shall
not be smaller than the system grounding electrode conductor
specified in 250.166 and shall comply with the provisions
of 250.28(A), (B), and (C).
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W9IQ

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Re: Question about copper braid for grounding
« Reply #35 on: October 24, 2020, 12:05:48 PM »

810 covers amateur radio antenna system, receivers and transmitters.

- Glenn W9IQ

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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KF5LJW

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Re: Question about copper braid for grounding
« Reply #36 on: October 30, 2020, 04:58:51 PM »

810 covers amateur radio antenna system, receivers and transmitters.
Correct, those are additional requirements to NEC 250 for CB and ham operators with a Transmitter.  connected to an outdoor antenna . Has nothing to do with a Receiver. NEC sees the transmitter for what it really is;  an electronic AC  power supply or Inverter. 

Your radio equipment is DC Powered, and you must meet the requirements of NEC 250 before you even take on the additional requirements of NEC 810. That is why I printed it so there is no mistake. Pretty easy to understand. What it is telling you is the equipment ground conductor cannot be any smaller than the supply conductors just like an AC circuit. If you run 6 AWG from your power supply positive and negative output terminals, requires you to use a 6 AWG minimum equipment ground conductor. You would not want to use a 14 AWG ground with a 6 AWG supply conductor. 14 AWG would burn up long before a 6 AWG if a fault were to occur, and cause an over current protection devices to fail and not operate. 6 AWG has much higher thermal mass and capacity, with much lower DC resistance. Basic fundamentals. Once hams understand all ground conductors are equipment ground conductors for safety, makes things much easier to understand.
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