There is a 20amp. 480V stick welder. It needs to be moved around in the plant as required. We will need at least 30m. long cable. The available wall recaptacles are 60amps. The welder has a 20amp. breaker. What would be the minimum size of cable required to connect this welder? Your replies are appriciated
Downsizing a cable.
- Thread starter lquadros
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downsizing cable
downsizing cable
Thanks for the answer. Is there a rule that explains this issue? Say for example we have computer power chords and other things that are 18 AWG. or lower. Other examples are pigtails of table lamps, light dimmers, christmas lights. I have also seen 16AWG extension cords being sold in the market with moulded 15amp plug. How is this possible? Any Ideas? I am trying to make sense of my issue with these wiring styles.
downsizing cable
Thanks for the answer. Is there a rule that explains this issue? Say for example we have computer power chords and other things that are 18 AWG. or lower. Other examples are pigtails of table lamps, light dimmers, christmas lights. I have also seen 16AWG extension cords being sold in the market with moulded 15amp plug. How is this possible? Any Ideas? I am trying to make sense of my issue with these wiring styles.
A good NEC reference is 240.5
add to that a determination of what Code is applicable.
In your case the NEC is applicable. If the cord is part of a piece of listed
equipment then the listing agency would determine the applicable codes.
add to that a determination of what Code is applicable.
In your case the NEC is applicable. If the cord is part of a piece of listed
equipment then the listing agency would determine the applicable codes.
cadpoint
Senior Member
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- Durham, NC
What is the specifications on the machine? What and where does the plant exactly need this equipment?
I believe there are some real design considerations.
It will never be a case of down sized the conductors because you?ll need to upsize the wire to maintain the desired voltage at point of use.
Depending on the size of the plant, my thought is that you will need multiply circuits not one circuit, one should certainly do a voltage drop calculation if you try to do a single circuit. Yes you could run a circuit out and split it into two individual connection points for an area of the plant, then do the same again from another circuit. This to me would be my maximum for a circuit. If you were to split the circuit use a directional indicator to transfer power so that two welders aren?t used at the same time on this one circuit, just something else to consider.
Here?s the numbers; say the machine has a draw of 12 amps, w-6 AWG, you limited to 200? (one way circuit length) ((remember this is a total linear run- up, down, across and sideways)), and maintain less than a 2% voltage drop; 8 AWG gives 3.2% VD.
Try your own voltage calc's. Here
IMO, One will use some pretty big wire if you did just ?one? circuit and daisy chaining your service forward into the plant.
Of course all this depends on the power source(s) in the plant and point of usuage.
Sounds like a fun project, Enjoy!
I believe there are some real design considerations.
It will never be a case of down sized the conductors because you?ll need to upsize the wire to maintain the desired voltage at point of use.
Depending on the size of the plant, my thought is that you will need multiply circuits not one circuit, one should certainly do a voltage drop calculation if you try to do a single circuit. Yes you could run a circuit out and split it into two individual connection points for an area of the plant, then do the same again from another circuit. This to me would be my maximum for a circuit. If you were to split the circuit use a directional indicator to transfer power so that two welders aren?t used at the same time on this one circuit, just something else to consider.
Here?s the numbers; say the machine has a draw of 12 amps, w-6 AWG, you limited to 200? (one way circuit length) ((remember this is a total linear run- up, down, across and sideways)), and maintain less than a 2% voltage drop; 8 AWG gives 3.2% VD.
Try your own voltage calc's. Here
IMO, One will use some pretty big wire if you did just ?one? circuit and daisy chaining your service forward into the plant.
Of course all this depends on the power source(s) in the plant and point of usuage.
Sounds like a fun project, Enjoy!
clarification to cadpoint
clarification to cadpoint
1.We have a machine specified for 30 amp. It is not a continuous duty machine. It is a stick welder.
2. We already have 60 amp receptacles through out the plant, already existing and wired. There is no issue with voltage drop. this welder is already working and being used. While changing the damaged cable, this issue has come up. My question is about the short circuit protection of 30m. long cable. The load side is taken care of, by the proper overcurrent device. Any ideas will be appreciated.
clarification to cadpoint
1.We have a machine specified for 30 amp. It is not a continuous duty machine. It is a stick welder.
2. We already have 60 amp receptacles through out the plant, already existing and wired. There is no issue with voltage drop. this welder is already working and being used. While changing the damaged cable, this issue has come up. My question is about the short circuit protection of 30m. long cable. The load side is taken care of, by the proper overcurrent device. Any ideas will be appreciated.
weressl
Esteemed Member
Yeah, this bugs me from day one since I am involved in the E-business. If I have a 20A OL protection at the end of my cable where would ANY overload above that 20 A come from? There is some compromise allowed in taps sizing concerning the same issue, but for the life of me I don not understand the technical justification for it. What does the length of a tap has to do with what current will it see?! Help, somebody put me out of my misery with a logical and technical explanation!
(I know what the NEC says...., but for gawdsake, we should be beyond of: because I say so.)
downsizing
downsizing
weressl,
In fact downsizing is done. As I mentioned in my second post. I do not know which rule is followed in those cases. I am from Canada. In our CSA code book we have what is generally known as 7m. and 3m. rules for downsizing cables. But in this case it does not apply.
downsizing
weressl,
In fact downsizing is done. As I mentioned in my second post. I do not know which rule is followed in those cases. I am from Canada. In our CSA code book we have what is generally known as 7m. and 3m. rules for downsizing cables. But in this case it does not apply.
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