# Arc hazard on controller terminals?



## major (Apr 4, 2008)

sabahtom said:


> I had to use thicker crimp lugs than expected in the DMOC controller. With the required 3 threads protruding at the end of the bolts, there's only 9mm between the negative DC and one of the 3 AC phases. The DC is 312v nominal.
> 
> If I understand rightly there should not be much risk of arcing between Phase C and the Negative terminal in the picture, because the AC output is high frequency and there would be a very short window for a voltage to develop between them?
> 
> ...


Spacing looks o.k. to me if it will be enclosed by a cover plate. But check your lock & flat washers. I always use the lock washer under the nut with a flat washer against the lug.


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## frodus (Apr 12, 2008)

It looks OK, but I think you could get some more clearance by doing the following:
[*]Put the right lug on the outside of the terminal, and leave the threaded end facing right.
[*]On the left lug, put the threaded end of the bolt facing outward. 

If you want to, you could get some sort of dielectric like fish paper. I can send you a small sheet if you want it. I won't be using it.


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## poprock (Apr 29, 2010)

Agree with Major. The neg terminal would be correct with a flat washer added under the bolt head.


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## dragonsgate (May 19, 2012)

sabahtom said:


> I had to use thicker crimp lugs than expected in the DMOC controller. With the required 3 threads protruding at the end of the bolts, there's only 9mm between the negative DC and one of the 3 AC phases. The DC is 312v nominal.
> 
> If I understand rightly there should not be much risk of arcing between Phase C and the Negative terminal in the picture, because the AC output is high frequency and there would be a very short window for a voltage to develop between them?
> 
> ...


I would do like was suggested and turn the one bolt on the left pointing away from the other. Just to be on the safe side you could put some insolating caps over the connections. Is that electricians tape around the cable lugs?


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## steven4601 (Nov 11, 2010)

No direct need for changes there, however if you insist, you can apply PET / Kapton or any other tape that has a dielectric rating other than duct/gift-tape .
Or coat the surfaces with conformal coating / PU.


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## dragonsgate (May 19, 2012)

steven4601 said:


> No direct need for changes there, however if you insist, you can apply PET / Kapton or any other tape that has a dielectric rating other than duct/gift-tape .
> Or coat the surfaces with conformal coating / PU.


I was just wondering because some electrician tapes tend to dry out or get gooey after time and comes on wrapped.


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## sabahtom (Mar 1, 2011)

_Is that electricians tape around the cable lugs?

_Thanks for mentioning the tape - it is electrician's tape, but it's 3M at $10 per roll so I hope it's good enough. I didn't have a hot air gun on the day so couldn't shrinkwrap it.

_I would do like was suggested and turn the one bolt on the left pointing away from the other. Just to be on the safe side you could put some insolating caps over the connections._

The bolt on the left would be phase C, good suggestion to turn it around. There's a better gap between the AC terminals so I'll turn bolt C around and look for some solid insulating caps.
_
Spacing looks o.k. to me if it will be enclosed by a cover plate. But check your lock & flat washers. I always use the lock washer under the nut with a flat washer against the lug. _

It has a cover plate. I'll fix the washers thanks.


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