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MV Grounding Cable

MV Grounding Cable

MV Grounding Cable

(OP)
Hi Guys,
I need to include grounding cable in cable specification for a 35kv service. I was looking at NEC (new) table 250.102(c)(1).
Is this a correct table for finding grounding cable? I am new to grounding and two things freak me out:
1- When we use grounding cable and when we use grounding (bare) conductor?
2- This table does not talk about voltage level. Is this because it is for grounding conductor and is applicable for all voltage levels (even High voltages)?



RE: MV Grounding Cable

(OP)
I found some information and decided to share here:

1- We don't pull ground bare conductor along with A,B and C power cables
2- Copper size for grounding cable should be sized based on above table 250.102(C)(1)
3- Insulation for grounding cable doesn't have to be same as power cables since they don't carry normal power in the circuit so as example for 35kv power cable we can use 600v insulation for ground cable
4- For each ABC, one ground cable shall be used so if you have 2 ABC or 3 ABC, you shall use 3 ground cables.

RE: MV Grounding Cable

In my opinion, UL 1072 it has to be followed if it is about grounding conductor within a cable.
I haven’t the last edition [2006, I think] with me. However, in my edition [1995] it is stated as follows:
UL 1072/1995 ch.21 Grounding Conductor
21.1 ...The covering on the grounding conductor may be for corrosion or other protection but shall not be credited as insulation. The covering shall be colored as indicated in 66.4 and 66.5.
21.2 BARE - Cable having interlocked aluminum or steel armor shall contain a grounding conductor that is not smaller in size or lower in resistance than indicated in Table 21.1 for the size of circuit conductors used in the cable. See 21.6.
If there are single-core cables then the grounding cable has to be provided as per NEC[2014] art.250 part X. Grounding of Systems and Circuits of over 1000 Volts.[from art 180 up to 194- it depends on grounding system ]
In my opinion, up 900 MCM it is the same conductor cross section area required-close to the above NEC recommendations.

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