Unacceptable Cable Lug

[uksparks]

Hi,

I am working on a project with someone at the moment connecting hundreds of batteries 2v 240Ah together for stored energy.

The joining links between the batteries are not that great on close inspection, I took one apart to look at it.

When you take the cover off, the rubbish is revealed. The reason I took the cover off is to confirm my thoughts about the cable having the current carrying capacity reduced by having a hole drilled in it. Basically they have put a round cable in a hole and then flattened the terminal to hold it, then drilled a hole through it.

The lug is so tight its actually cut through a significant number of the strands and severely damaged a large number of the remaining strands putting a dent in in creating a hot spot and reducing the CCC.

Then what is left is a thin edge to the strands stuck into the edge of the metal lug, the remainder of the lug is not going to be as effective as the first edge, but even then, a lot of the strands have been severed.

As you can see I have cut it back and fitted a proper 70mm2 'PEPL' cable lug to the end using the proper tools, this does not damage and of the strands as is very tight.

Surely as it is, this cable does not comply at all with any British Standard and in my opinion should not be used as it if you are reliant on the size of the cable for its current carrying capacity which you are, not only will this give you high resistance joints through your battery storage, but it puts you at a far greater risk of fire due to the fact you will be trying to pull more current through the cable than the terminal can take due to the damage in the manufacturing process.




So I stripped it off and put a proper end on it, a round end to suit a round cable, just missing the shroud as need to source a suitable one.



Your thoughts please... I would like a couple of reg numbers to show the customer as he has around 500 of these cables at present, and I am going to be making him some new ones and he will be getting a refund from the Chinese company he bought them from!

 

[Marvo]

Yeah, it reeks of mass production corner cutting and I don't see it conforming to any known regulations. Also high current ELV battery installations are inherently prone to being a fire hazard and this kinda thing is doing nothing to improve safety, quite the contrary in fact.

 

[uksparks]

Yeah, it reeks of mass production corner cutting and I don't see it conforming to any known regulations. Also high current ELV battery installations are inherently prone to being a fire hazard and this kinda thing is doing nothing to improve safety, quite the contrary in fact.

Do you know which reg numbers might be related to this, basically I am looking to show him a few regs as he is going back to get his money back you see, so would like to back it up with regs if possible.

I think its going to be pulling a couple of hundred amps so quite a lot.

 

[Marvo]

I'm not sure of the UK reg numbers I'm afraid, I don't work to them usually so I'm not familiar. Maybepost a question in the solar forum, the guys in there are probably familiar with storage battery installations and the appropriate UK regs.

 

[Richard Burns]

Apart from the damage to the strands the lug would still provide the same sort of current transfer as a normal lug, although I admit those look pretty poor.
You may be able to find a suitable cover for your lugs here.

 

[uksparks]

I'll take the big book to bed and have another look for some suitable regs, one about chopping strands down in cables might be a start, and damage in terminations. I'll find them.

 

[davesparks]

I'll take the big book to bed and have another look for some suitable regs, one about chopping strands down in cables might be a start, and damage in terminations. I'll find them.

You're not really in 7671 territory here,

 

[uksparks]

Would terminations not come in to it? What would it fall under? I would have thought it would as its being connected to a grid tied inverter and used to generate 230v, the big install is good for 150kWh

 

[Andy78]

Would terminations not come in to it? What would it fall under? I would have thought it would as its being connected to a grid tied inverter and used to generate 230v, the big install is good for 150kWh

As Dave says, probably not best off looking in 7671 as that covers installation of selected wiring and equipment. If these pre made cables are not suitable, you should not select them.

I would bet that there is probably a BS that covers crimped terminations though including methods and equipment. That's what you need.

 

[Marvo]

You're not really in 7671 territory here,

I just ran a database querie on my IEC standards set and I think IEC 61238-1 is the international standard but I don't have time to read it thoroughly at the moment. It does refer to BS7609 as being a recognised standard for inspection of crimped terminals so maybe start there if you have access to the British Standards collection. If not I'll see if I can lay my hands on a copy and let you know what it says.

 

[davesparks]

Would terminations not come in to it? What would it fall under? I would have thought it would as its being connected to a grid tied inverter and used to generate 230v, the big install is good for 150kWh

Pre manufactured equipment/parts will have its own set of standards.
7671 doesn't apply to machines/appliances etc. You might as well try to apply 7671 to the internals of your dishwasher!

 

[UKMeterman]

Hi,
Try this way http://www.ipc.org/TOC/IPC-A-620.pdf sign up to this list smart-e-link | SMART Group and ask people to tender.

 

[Marvo]

Okay, according to BS7609 2009 I just found, this type of termination wouldn't qualify as a compression (or crimped) terminal;

3 Definitions
For the purposes of this British Standard, the following definitions apply.
3.1 connector
component or assembly of components designed to accept one or more conductor(s) for the purpose of making an electrical connection
3.2 mechanical connector
assembly designed to clamp conductors by mechanical screw force
3.3
insulation-piercing connector
mechanical connector which does not require removal of the conductor insulation to make an electrical connection
3.4
compression connector
component designed to make a connection by deformation of the barrel around the conductor NOTE The term compression covers the term crimping
3.5
barrel
part of a connector designed to accommodate the conductor
3.6
palm
part of a terminal lug formed flat to make a bolted connection to an equipment terminal
3.7
terminal lug
connector comprising a palm and a barrel, for connecting a conductor to an equipment terminal

I'd suggest, as Dave mentioned, this type of termination might be suitable for an earth bonding braid or strap where there's no load current as such but it wouldn't be suitable for a current rated application because it's not a compression termination by the definitions above and therefore it also couldn't be inspected and tested according to BS04579.

 

[PEG]

Those pre-made Chinese yokes,look just like many i have seen,on bikes,quads,generators and workshop equipment,from that continent.

With that standard of construction,and the number involved,the chances of failure is high. If that merely ends in a shut-down,then the least someone will have to do,is replace the failed link,with a properly constructed item. Then,depending which side of the purse you are stood,there will joy or dread,of the swapping of all the others...

Whatever you decide,put in place the mechanics of a plan,which allow you later,to say "You were told..." :30: