Hi I have a 150 hp, 460 VAC, 3 ph explosion proof motor made by B?? (no brand name but you can deduct) . I have the main junction box in center and in one side of the motor I have one auxiliary box for 120VAC heater (incorporated in motor) and in other side other auxiliary box for thermic protection switches NC in series.The heater has 2 wire and no ground wire same as thermic switches. They use LB for connection with no ground lug. I came with explosion proof flex and of course seal fittings. Customer specs say to have all separated in different rigid pipes. As a rule I provide one ground wire at least in all the conduit. Where I have to connect the ground wire for the heater since I do not have the connection ground wire or at least a ground lug in LB (usually LB is use for pulling wires).The easy way is to replace the LB with proper explosion proof junction box with ground lug. Someone can help me with article in the NEC because we pay big bucks for this motor (17000$) and B?.. technical support say their motor is OK falls under NEC rules no violation moreover Tech support say they ask engineer and the heater ground is internal connected to the main ground and main junction box . I ask where I connect my ground wire? No answer to this question. Motor is UL approved and no NEC violation. Here is the answer.? - Right, none of these devices come with grounding leads - we don't manufacture space heaters, t-stats ect. They are off-the-shelf purchased materials. This is standard practice and has been for over 3 decades. These are all low-voltage devices and they all are within the requirements of the NEC.? If something is bother me is : ?standard practice and has been for over 3 decades? Space heater are 120VAC!!!????
Ground wire connection on motor heater.
- Thread starter cosas
- Start date
- Status
weressl
Esteemed Member
If it is a motor rated for Class I, Div. 1 shouldn't the connecting box for the heater be also an X... fitting and not an LB? As far as the grounding goes a grounding bushing - with a short nipple added from the inside - would solve your issue? I know it would be crowded, but hey, it solves the problem.
http://www.cooperindustries.com/con...ries-groundingplatesandgroundingbushings.html
As far as B.. concerned, it is only somewhat of an oversight as they were thinking of the conduit providing the grounding, but for the same argument how about the grounding lug in the main peckerhead?!
weressl
Esteemed Member
I got that and that is why I was saying that if they provided it in the main JB, why not in the other ones. THe potential logic may be that with 480V the individual ground wire is more commonly applied than with lower voltage/power circuits.
- Status