Arc Blast Blanket Help

[Frenetic]

I work for an electrical utility, in particular, I work for the downtown network group (I use to be a distribution planner). If anyone is familiar with a network system, the fault currents easily approach 200k (or more) and all occuring within a very confined area (vaults/manholes).

Most major metropolotian areas are served from networks; they're very old, very reliable, but extremely expensive since everything is done in duplicate or more (up to 10x or more!).

I know Con Edison did a study on Arc Blast blankets, but I'm curious if anyone else here has any experience with them? We're currently examining them ourselves, but we're finding information about these blankets difficult to come by. Does anyone else use these? How are you installing them and have you actually had a fault incident with these blankets in use?

Thanks in advance!

 

[zog]

We have used them for cable splicing in manholes. The splicer would enter the manhole in HRC 4 PPE, wrap the energized cables with suppression blankets, and then change to HRC 2 PPE for doing the splice. Far from a perfect procedure but the best balance of risk and safety we could come up with.

Problem is with the supression blankets there are too many variables, I few years ago I witnessed some testing of supression blanket testing and while they obviously do supress the arc somewhat, in an enclosed environment like a manhole the arc only has so much room to expand in, the arc tends to "Squirt" out the sides of the blanket and bounce off walls. There are some videos on line somewhere of supression blanket testing, if I find them I will post links.

Your best bet is to "Engineer out" the arc flash hazard.

 

[Frenetic]

Thanks Zog.

We're trying to do our due diligence to protecting our cable splicers. It's dangerous work, but we're doing all we can.

I'm trying to put together a procedure for these blankets and it's proving more difficult than I imagined simply because of the many variables you mentioned, which is something I can foresee.

 

[charlie]

We're trying to do our due diligence to protecting our cable splicers. I'm trying to put together a procedure for these blankets . . .

I do not nor did I ever work in our CBD (central business district) so I can't help. However, I assume your company is a member of EEI and has contact with other electric utilities. Your Standards division would be very aware of those types of contacts. You can pose your question to other companies in that manner and get some valid responses with test data.

This forum is mostly for people in the inside electrical industry and "most" do not get into any work in the confined areas that you are dealing with. Additionally, the NEC applies to almost all of their work and you are working under the NESC.

 

[Frenetic]

I do not nor did I ever work in our CBD (central business district) so I can't help. However, I assume your company is a member of EEI and has contact with other electric utilities. Your Standards division would be very aware of those types of contacts. You can pose your question to other companies in that manner and get some valid responses with test data.

This forum is mostly for people in the inside electrical industry and "most" do not get into any work in the confined areas that you are dealing with. Additionally, the NEC applies to almost all of their work and you are working under the NESC.

Well, it didn't hurt to ask since I know a lot of people here deal with Arc Flash hazards. I don't believe there's any governing body that even mentions Arc Supression blankets, let alone governs them, NESC or whatnot. I came here mostly looking for grounding help, and I like the information I read here, especially from the perspective of the many inspectors and electricians that post here :smile: . Engineers sometimes live in a bubble and it's good to see all perspectives.

In all honesty, the network system in our utility is like a long lost cousin. Most here don't understand it, especially in our standard's group (sadly as that sounds). Out of sight and out of mind, since it's so reliable. In fact, they didn't even have any engineers working in this group until recently (if you can believe that) and now management is actually worried and installed a few engineers to manage it.

I've spoken with Con Edison network engineers and they've been very helpful, but I was just trying to get additional perspectives, especially from those that aren't necessarily related to the utility industry but use these blankets nonetheless, especially with the new Arc Flash standards.