Lashing Conductors - Bus Tap

[overkill94]

The lashing of supply conductors seems to be a fairly new requirement and all I can see in UL 891 is section 6.3.3.1 which indicates that a marking shall be installed on new switchboards with bracing instructions to satisfy the short-circuit requirements. I've been doing inspections on modified switchboards that are tapped off the line side for new photovoltaic installations. Since these are now considered service conductors, are they required to be tied up? What if it's an older gear and there are no lashing instructions? Thanks!

 

[Tony S]

Watch this

https://www.youtube.com/watch?feature=player_detailpage&v=HmnrJa7Zk0A

 

[shortcircuit2]

Cable lashing techniques at terminations in switchboards are different from the cleating in Tonys video link. I agree that you have a valid concern for Lashing the new service conductors. Although engineering and/or manufacturer consulting may be required to determine the need in your case including how the taps are done. Fault current level needs to be considered.

 

[jim dungar]

Fault current level needs to be considered.

Yep.

Cable lashing is not a new requirement. Lashing has normally been required when fault currents exceed 65kA. For the most part lashing is required to keep the conductors inside of the 'aluminum' lugs, commonly found in switchboards, during bolted fault conditions.

 

[Tony S]

Could I ask what you define as lashing as opposed to cleating?

Normal practice for our company would be to secure the single conductor with aluminium half cleats as close as practicable to the termination. Therefore removing any mechanical stress on the termination in the event of a fault.

The effect of heavy fault currents is often ignored. It resulted in the death of an electrician when a fault occurred. The steel decking plates over the cable trench were thrown in the air and one literally sliced him in half.

 

[shortcircuit2]

Cable Lashing with 3/8-inch rope with a minimum tensile strength of 2000lbs.

Seimens WL Switchboard instructions depict this technique on page 21 of these instructions...

http://w3.usa.siemens.com/us/intern...ribution/docs_EABU docs/SIE_IS_Switchgear.pdf

This specification would apply to low voltage Switchgear under 600volts, which I believe the OP is dealing with.

Do you have instructions of Lashing with cleats?

 

[Tony S]

Manufactures picture I’m afraid. The sites I worked on taking photographs would lead to instant dismissal.

 

[iwire]

Thanks Tony.




I think this link illustrates what the OPs installation would be like.

http://blog.washingtonelectric.net/lashing-utility-conductors/