BIL/Lighting Safety

To: mail11: ;
Subject: BIL/Lighting Safety
From: THIS SPACE LEFT BLANK <pierson-at-msd26.enet.dec-dot-com>
Date: Sun, 9 Jun 96 15:49:21 EDT
Cc: pierson-at-msd26.enet.dec-dot-com

I've never seen anything resmbling a figure for 'safe separation' for a
lightning stroke.  Lighting comes in a variety of sizes, all potent,
all unpredictable.  I suspect its an unanswerable question....

BIL

>>ANYWAY, i can put in the tables, if interested, sample:

>>kV (working    BIL (kv)	      Clearance to		

>				conductors	    people	roads
>>7.5KV           95               6"        7"      8 ft         20 ft

>>Now i will ASSume everyone on this list understands that 7.5 KV sparkover is
>>A LOT less than 6"  <grins>, with the 6" providing working margin for
>>95 KV surges, lightning, or other...	

>But I do question their 8' gap for 'people' and 20' for roadways. Is
>the road more sensitive to a lightning strike than a person?;)

	The standard implicitly (explicitly???) covers overhead clearance from
	wires, busbars, etc, foo, mumble.

	8' for people allows 6' high people plus 24" margin.
	20' for roadways allows 18' high trucks plus....

	grins
	dwp
	(6ft and a smidge...)