120/240v 3 Wire System vs 120/240v 4 Wire System
120/240v 3 Wire System vs 120/240v 4 Wire System
(OP)
We have an application where 120v 3 wire equipment must operate in older buildings where single phase 120/240v 3 wire system is the only available power. The manufacturers of the equipment state that the three prong plug must be utilized for proper operation. The only solution I have come up with is to use a portable transformer 240v - 120/240v 4 wire to establish a true ground system. Any comments or ideas?






RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
1. Implicit assumption by future users that the ground is good because there is a 3-prong receptacle.
2. Water piping may not be electrically continuous and of sufficiently low resistance for fault clearing current.
3. The water pipe may not be connected to the building service entrance ground. If it is not, this can be a very significant fire and electrocution hazard for users of plumbing fixtures should there be a ground fault in the utilization equipment.
RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
3 wire means 2 hot and a Neutral. Ground is always extra.
(Similarly 4 wire is 3 hots and 1 N, plus ground)
What are the three prongs? 2 hot and a ground? or 2 hot and a Neutral?.
1 hot, 1 N and 1 G is not a 3-wire system.
The Neutral of 120/240 must be grounded at the service entrance equipment. I am not sure where the problem is and why u need a transformer to establish a ground?
Is it that this plug does not have a ground? Is it required by Code? I would think so.
RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
I am a bit confused.
///Nothing wrong with that.\\\
3 wire means 2 hot and a Neutral.
///True.\\\
Ground is always extra.
///Yes.\\\
(Similarly 4 wire is 3 hots and 1 N, plus ground)
///Yes, in majority of cases.\\\
What are the three prongs? 2 hot and a ground? or 2 hot and a Neutral?.
///1 hot, 1 neutral and 1 ground if related to 120V receptacle which is normally installed in residences, commercial and industrial spaces.\\\
1 hot, 1 N and 1 G is not a 3-wire system.
///Not quite. It is two wire system plus ground.\\\
The Neutral of 120/240 must be grounded at the service entrance equipment.
///Yes.\\\
I am not sure where the problem is and why u need a transformer to establish a ground?
///The transformer is not needed. The correction of wiring deficiencies is needed, which is often very expensive and troublesome.\\\
Is it that this plug does not have a ground?
///Yes.\\\
Is it required by Code?
///The ground and three prong 120V receptacles are required by NFPA 70-2002 National Electrical Code.\\\
RE: 120/240v 3 Wire System vs 120/240v 4 Wire System
Any hopes of still getting the Bill Mitchell demo software we talked about in another post? My email address is listed at the top of the following post FAQ800-480. Thanks in advance.
-Joest