Electromagnectic Effects

[ED17]

We do lots of testing on social housing and came across this yesterday.

Someone has recently replaced the consumer unit with an AMD3 wylex unit. They have taken the main tails and earth through three separate 20mm stuffing glands. What code should we be giving it, C2?

 

[telectrix]

i'd be inclined to give it a C3, as with the average load in a domestic property, the eddy currents will be too insignificant to cause any danger.

 

[Pete999]

i'd be inclined to give it a C3, as with the average load in a domestic property, the eddy currents will be too insignificant to cause any danger.

IMO it defeats the idea of fitting a metal CU, why?. because you are adding a potential heat/fire source to the CU, must have been installed by someone who doesn't know what they are about.

 

[telectrix]

i have to hold my hands up to having done the same, once, on a 3 phase office installation. been in 8 years and the place still stands. a couple of visits when the installation has been running loaded, no sign of warmth at all around the tails.

 

[Lucien Nunes]

Agree with Tel, it's technically wrong but at the currents under cosideration the effect will be barely noticeable. John Ward made a demo video, not 100% representative as the CU was outdoors and there was no control thermometer etc, but he got up to >100A with a 2°C rise in the CU wall. https://youtu.be/hg5eZkq2KgE

 

[bigspark17]

It has to be a C2. We are installing installation to current addition of bs7671. In this instance reg no 521.5.1 should be adhered too no room for manouvere. Tel why did you not adhere to this in your post, out of interest what prevented you from doing so, out of intrest.?

 

[westward10]

i'd be inclined to give it a C3, as with the average load in a domestic property, the eddy currents will be too insignificant to cause any danger.

Technically wrong but I have to agree the chances of any danger being caused is probably zero. I would also C3 it unless you want to make a point of their error.

 

[ED17]

Technically wrong but I have to agree the chances of any danger being caused is probably zero. I would also C3 it unless you want to make a point of their error.

That's my problem. I don't want to drop anyone in it, but then again I don't want dropping in it by giving out a satisfactory report then someone else coming along and saying it isn't.

 

[Wilko]

IMHO it's not immediately dangerous, but its not compliant with current regs on a current installation. I agree with Pete #3, so I'd go C2 and maybe the orig installer gets to do the rework. That always sharpened my attention, I recall. Maybe I'm too harsh. Cheers, David

 

[Bobster]

Personally I'd mark it as a C2 and note that it got the unsatisfactory because it goes directly against reg 521.5.1.

 

[westward10]

That's my problem. I don't want to drop anyone in it, but then again I don't want dropping in it by giving out a satisfactory report then someone else coming along and saying it isn't.

I suppose you need to say to yourself, is it Potentially Dangerous (Code 2), most posts on here feel it isn't but Posts 6 and 10 feel it does. "Potentially Dangerous" is asking is there a potential for it to happen, not necessarily today or next week but at some time. Go with what you feel and don't worry about the consequences for others.

 

[telectrix]

@bigspark17. reason was that the metal 3 phase isolator was supplied by A.N Other and the casing was too shallow to fit anything bigger than 25mm stuffers/glands. so they had to go in individually. i stick with a C3 though, as there is no danger , immediate or potential. bearing i mind that with plastic glands the closet the casing is to the cable is about 28mm,so whatever eddy currents are generated will be very weak.tin hat on.

 

[Midwest]

Personally, I always find it a bit of a task terminating tails into the main switch when run through the same hole, without some twisting or moving of the isolator. How they've managed to do it via two holes involves some skill

 

[westward10]

@bigspark17. reason was that the metal 3 phase isolator was supplied by A.N Other and the casing was too shallow to fit anything bigger than 25mm stuffers/glands. so they had to go in individually. i stick with a C3 though, as there is no danger , immediate or potential. bearing i mind that with plastic glands the closet the casing is to the cable is about 28mm,so whatever eddy currents are generated will be very weak.tin hat on.

Couldn't you slot the holes?

 

[David M]

Couldn't you slot the holes?

Yes that would be the easiest solution, then seal it up.

Without actually seeing the situation, as it is non compliant and the actual potential danger risk is extremely small I would probably C3 it.