Xfrmr Lugs?

[Alwayslearningelec]

Have a bunch of 45 & 75 kva xfrmrs I'm buying and installing. Do they come with or need lugs kits? Not sure why I'm thinking there's something regarding the termination that may not come with the equipment. Thanks.

 

[texie]

Have a bunch of 45 & 75 kva xfrmrs I'm buying and installing. Do they come with or need lugs kits? Not sure why I'm thinking there's something regarding the termination that may not come with the equipment. Thanks.

Typically you need to order lug kits.

 

[Alwayslearningelec]

Typically you need to order lug kits.

Thank you. Anyone happen to have pic of what these look like and maybe even mounted in xfrmr?

 

[farmantenna]

typical single or double foot lug mounted with 5/16 bolts and nuts. nothing special

 

[Alwayslearningelec]

typical single or double foot lug mounted with 5/16 bolts and nuts. nothing special

Thanks. Single or double foot???? I've heard of one or two hole lugs..lol

 

[Moore Power]

We call them chair lugs, just a standard lug with a bolt hole and a screw terminal. I generally do a double lug for the XO because you will have your Neutral and your MBJ land there.

 

[MD Automation]

All of the small transformers like that I've ever used in our old shop came without lugs, as Texie noted.

I'd almost always fit a transformer up with bolt-on lugs, the simplest (single hole) look like these...



As farmantenna noted, they are very common, any supply house will have something like this. Just need to know how big a wire you are looking to land there, they all have a min and max wire size.

Hope this helps.

 

[Alwayslearningelec]

All of the small transformers like that I've ever used in our old shop came without lugs, as Texie noted.
Here is a pic of one wired up with ring terminals...

View attachment 2569223

But I'd almost always fit a transformer up with bolt-on lugs, the simplest (single hole) look like these...

View attachment 2569224

As farmantenna noted, they are very common, any supply house will have something like this. Just need to know how big a wire you are looking to land there, they all have a min and max wire size.

Hope this helps.

Thank you very much Why wouldn't xfrmrs come with these already installed?

 

[MD Automation]

I would assume one reason might be it's difficult to predict exactly how a customer is going to use and wire a transformer. Are they going to use smaller wires and not load the xfmr near it full rating? Are they going to run single sets of large wire or parallel sets of smaller wire?

It would be hard to pick a single lug size that would not disappoint somebody.

So they choose to disappoint everybody and save a few pennies

 

[Alwayslearningelec]

I would assume one reason might be it's difficult to predict exactly how a customer is going to use and wire a transformer. Are they going to use smaller wires and not load the xfmr near it full rating? Are they going to run single sets of large wire or parallel sets of smaller wire?

It would be hard to pick a single lug size that would not disappoint somebody.

So they choose to disappoint everybody and save a few pennies

 

[texie]

I would assume one reason might be it's difficult to predict exactly how a customer is going to use and wire a transformer. Are they going to use smaller wires and not load the xfmr near it full rating? Are they going to run single sets of large wire or parallel sets of smaller wire?

It would be hard to pick a single lug size that would not disappoint somebody.

So they choose to disappoint everybody and save a few pennies

Sometimes company policy or job specs may require, say, compression lugs is one reason. Other reasons such as sizing.

 

[Alwayslearningelec]

Sometimes company policy or job specs may require, say, compression lugs is one reason. Other reasons such as sizing.

So you can have mechanical or compression lugs in xfrmr? If the supply has the job specs they should cover.

 

[electrofelon]

Note 450.10 which is newish. I havent ordered a new dry type in quite a while, Are they coming with this bar?

450.10 Grounding. (A) Dry-Type Transformer Enclosures. Where separate equipment grounding conductors and supply-side bonding jumpers are installed, a terminal bar for all grounding and bonding conductor connections shall be secured inside the transformer enclosure. The terminal bar shall be bonded to the enclosure in accordance with 250.12 and shall not be installed on or over any vented portion of the enclosure

 

[Moore Power]

Note 450.10 which is newish. I havent ordered a new dry type in quite a while, Are they coming with this bar?

450.10 Grounding. (A) Dry-Type Transformer Enclosures. Where separate equipment grounding conductors and supply-side bonding jumpers are installed, a terminal bar for all grounding and bonding conductor connections shall be secured inside the transformer enclosure. The terminal bar shall be bonded to the enclosure in accordance with 250.12 and shall not be installed on or over any vented portion of the enclosure

All of the ones that I've done in the last few years have had the terminal bar installed with the paint already ground off. Sometimes there are lugs installed already for the primaries and secondaries but usually not.

 

[hillbilly1]

Kinda hit or miss on lugs, two of the last six I ordered this year came with lugs. If you’re ordering from a supply house, your salesman should have included them if you ordered a package deal with panels. Be careful on ordering step lugs, they may not clear the cover, and make a nice hole in it when energized. LOL! (Came in behind one like that, electrician sat on the transformer, and rested his foot against the cover)

 

[MD Automation]

All of the ones that I've done in the last few years have had the terminal bar installed with the paint already ground off. Sometimes there are lugs installed already for the primaries and secondaries but usually not.

Agreed. Here is a quick pic from my old shop of typical grounding bars on a new transformer.



Now I thought the holes on the above bar were hilariously oversized for the kVA rating of this unit (maybe 30 kVA??) The lug specs were #12 up to 350. I would not trust a #12 in that hole.

I've also had the opposite problem of manufacturers installing a ridiculously undersized bar, both in terms of hole size and number of holes.


Just something to be aware of. I often times swapped out the installed bar for a more appropriate one.

 

[Alwayslearningelec]

Thanks for all the responses. Does the same apply for disconnect switches?

 

[infinity]

Regular disconnects always have the lugs attached. For transformers I guess it depends on the way that they're ordered. I've seen them come with or without mechanical terminals. I've never seen them come with crimp on terminals. If you had a job spec that required crimp terminals it would not make sense to buy transformers that had mechanical terminals that would need to be removed and thrown away. This one (75 KKVA) had the terminals attached from the manufacturer.

 

[PCBelarge]

Regular disconnects always have the lugs attached. For transformers I guess it depends on the way that they're ordered. I've seen them come with or without mechanical terminals. I've never seen them come with crimp on terminals. If you had a job spec that required crimp terminals it would not make sense to buy transformers that had mechanical terminals that would need to be removed and thrown away. This one (75 KKVA) had the terminals attached from the manufacturer.


View attachment 2569231

X/O with 3 terminations is great. And an terminal bar mounted to the enclosure with 3 terminations. Covers all of the grounding terminations necessary for a code compliant installation. Hardly anyone gets the ungrounded terminations mixed up.

 

[Alwayslearningelec]

Forgot to ask, so this mean a lug kit would be required for primary and secondary?