You have mail Chris and my number mate

Rob

Thanks Bob, I noticed you seem to visit the site more regularly again.

Sorry perhaps not clear in my post, I'm ok with having to work out what is being used etc so not to overload, it’s just other people! 

Hence my question, do you get a "non-muppet" to work out and then they are not allowed to alter or has anyone come up with a novel solution.

I was wondering if say we put a tag near the plug telling them the current draw (amps) to save them having to work it out or manhandle bits of equipment to get to the info. Then all they need to know is not more than 13A in total (if it is a 13A extension) ie

Laptop                            0.5a             65W

Monitor                           0.5a           100W

Hoover                              9a          2000W

These three in a 13amp extension would be ok for instance, but if you added a kettle it would not be.

I just know that people will change things around between my visits, and was hoping someone had come up with a Muppet proof system. I don’t want to say sorry you are not competent to plug anything in, but I want to have something really easy so they don’t accidently overload an extension.

Yes, I know, stop employing muppets, but is there a test for that? and I’m not given a vote on new recruits anyway.

So how does everyone do it.

Chris

Rob has just beaten me to posting.

Strictly speaking the 13A fuse within the BS1363 plug should be adequate to protect the extension lead from overloading, as long as the lead is designed and manufactured in accordance with the relevant standards.

IF it is compliant then it should be able to take the 13A load indefinitely, and hopefully the potential small overload for long duration, and, the over current which will open the fuse.

The most difficult to prevent is the small overload of long duration, say 14 or 15A, or perhaps even up to 20A.

This is where as Rob says it gets boring, it's the time/current characteristics that get you! ;)

One thing you need to be very careful with is long extension leads, and, "daisy chaining" of leads.

Thanks both

Yes, we insist on fully uncoiling any coiled extension leads, and no daisy chaining allowed.

So, from what you are saying, is that if they accidentally go over the 13a total of the extension then the fuse would blow and return it to a safe condition, so I should not be so concerned. However, if the current is just over the 13A for a period of time then this may not be quite enough for the fuse to go, but there may be a heating effect on the extension at some point. 

I don’t actually think we have any instances where we are overloading, but want a more proportionate approach that I can detail, than that of our FRA who feels no one should ever use an extension lead, ever, ever, ever. Our office ones are mainly just normal low powered office equipment and things like the vacuum are plugged into a wall socket to be honest. Outside of the office extensions are used as we require to use the odd power tool etc away from a wall and can’t have overhead supplies. But it then is one extension with one thing plugged into it and fully uncoiled.

I thought if I had a written method of control and simple process it would remove the backside covering none proportionate notes of the FRA.

Also thanks Invictus, off to look at your link and a reference mad by Bob

Cheers

Chris

Thanks Bob - yes Max Zs sound fun, and its not how much sleep you can get - well it is Friday :o)

Looked up the issue about RCD and max lenght of cable, didn't know that so thanks, found this link that others may be interested in so thought I would share.

electrical.theiet.org/wiring-matters/21/site-safety.cfm?type=pdf

or if link does not work search "2006 21 winter wiring matters site safety portable electric tools"

Seems quite practical advice.

Cheers

Chris

Captcha = DuNZs1Y  or could be read "Dunce i  Yes"

Use of extensions increases risk of cumulative leakage currents exceeding safe limits under fault conditions.

Longer power cables are usually readily available, and position of printers etc. is often limited by the practical length of USB cabling.

Our house rule is extensions are for temporary use only (and no daisy chaining!)

have a look at

cpc, rswww.com and netshop.co.uk

you can get longer kettle leads, appropriate to your length needs,

or adapters for kettle to kettle connections (usually used in switch rooms/comms cabinets to allow you to remove international plug type adaption requirements. 

don't know if you want to look at class b,c,d, circuit breakers, or if it's appropriate in your setup for slower trip, or if you need to move the otherway, or could install a new ring for computers and split load? 

can you shorten the circuits to make them less likely to take too long to trip,

or use thicker wiring for specific circuits or new additional spurs and remove sockets further away / extensions on the end of them

could you put in a db closer to the ring main/circuit so that there is less distance to travel like that, on the end of a new spur? 

had lots of problems like this, but the electrician's answer seems to usually be re-wire and renew... new db boards etc 

have you got a wiring diagram and/or is it all labelled/ can it be surveyed before going to next steps and options plan.

Paul,

Suggested that the use of various breakers as they may solve some tripping issues where appropriate, (note caveat placed on where appropriate). 

suggested additional ring if that would assist splitting load and (at the same time) perhaps could provide benefit by moving sockets off existing to a new supply.

we relatively recently had a seperate supply installed for a computer room, (was using ring main), however sometimes had had the circuit trip.

what we decided to do was to put a spur to a local db (for that room) and sockets off it to enable localised isolation and at the same time, additional "Commando" sockets for 2x upses,
to then distribute the power within the cabinet we used pdu's with kettle lead connections - note mention of kettle-kettle leads of various lengths 

with some of the cables for server/other devices, we needed approx 3m rather than 0.75 to 1m leads (as has been mentioned ref leads getting shorter, so we bought a selection of different length leads to cable appropriately within the cabinet. (also re-used in some locations for longer leads required in office as had them to hand. - bought both moulded with uk plug and kettle(m)-kettle(f).

as such, I mentioned that such leads are available, and as such could solve the problem with a longer lead from computer to wall (as well as short computer lead & extension) - direct connection to socket rather than on an x-gang extension lead. 

In addition, transformers/mobile chargers seem to be everywhere these days, and it will always be a challenge to pat test when brought in by users, so perhaps use of sockets with usb, (with strategic locations that people will use), could provide a way of removing the desire to use such devices. We typically found at pat testing some devices had been damaged plastic or lead pulled and required some replacements when found. 

with reference to tripping of devices a long way from the rcd, some devices we had to use slower trip circuit breakers,(welder &extension on specific socket) - had multiple discussions ref where additional sockets could be, and installed some, but it always had to be next to work-piece and "mobile" - hence extension. - this caused an issue with nusiance tripping so looked at moving down breakers, where it plugged in specifically, moved sockets nearer to db, shortened lengths of extension.  

With other circuits, normally we were going the other way, especially with the new db installation,(b) (and in addition, the new sockets meant that the area covered was significantly diminished, so distance from "last point" to rcd was a lot shorter, and load on the former ring was removed, so it became less of an issue with other devices. 

tripping was on a morning, and eventually found people were using electric fan heaters "cos it's cold", so we changed heating times on the boiler, and i migrated a couple of the heaters to a locked room, and gave them fleeces to wear, seemed to be the actual problem solved. for the ring main, main computers weren't tripping any more so less of an impact on others than was.  

again, the benefit of the seperate supply meant that it was in a secure computer room, unlikely to be affected by other devices overloading the ring or having too much on the circuit at the same time, no hoovering. 

at the same time, as a dr measure, we installed a switch-over so we could provide a proportion of power the site via a plug in generator - un-affecting dbs at the time of an outage.

this was because we had had a damaged main cable in the past, and a generator would provide an option to get doors up, and provide some basic functionality without having to take generator to location and apply power from a generator locally to open a roller shutter door in a power cut. - doing a manual paper system and then re-entering data is not fun.  

we always had on-going discussions ref fixed and pat electrics, and I ended up doing the wiring regs c&g course to understand more of the problem so that could evaluate different options with the electricians.

I would advocate same to others, so that can communicate in same language, reference docs, and design together what is an appropriate solution for your environment, taking account of people, activities and sensitivity to maintenance, outage, recovery etc. 

I had responsibility for iso management systems of the site, electrics, and paying the bills. 

I wanted to know what I was paying for, why, and what the options were. 

Over a large site, with lots of requirements, someone has to discuss with contractors about oversight of everything, and that person was me. 

In addition, I would state that I have seen some people "retain" information from operators so that the "right decision" is made, it is beneficial to evaluate who it is "right" for, and to evaluate what's behind the decision making process, because sometimes underlying assumptions/decisions aren't always in line with everyone's view.  

Good documentation is always worthwhile, and as such knowledge of the system's setup can be invaluable, and I feel an activist approach towards the electrical requirements of the business helps to understand what you are being asked to pay for, why it's important, and provide less of a shock when invoices come in, and lists of outstanding work are being reviewed, and clearing off work completed from a test report.

In addition, as most will understand, budgets are always limited, and investment needs to be targeted appropriately, sometimes I would feel that there was a desire to remove/replace equipment when that may have had a different option as a method of addressing the problem.

some replacements, are definitely worthwhile - emergency lights to LED for example, (remedial decoration not included) however serious thought needs to go into other activities before planning to do "a list" over a weekend. 

in addition from a dr perspective, it is always good to know where the important switches are (and those to not turn off), so that the person assisting with activities on site knows where things are to support whatever activities are required.

I would advocate to anyone taking responsibility for a site that they should understand more about the "electrics" what's it do, why are they where they are, what do we have/need etc. 

Originally Posted by: chris42

My question is, has anyone come up with a nice easy way to ensure that people don’t overload these extension leads?

How do you control their use?

Chris

In the past I've calculated the current taken by the item and written this numerically on the plug top - i.e. 1000W rated appliance / 230v = 5 rounded up. I've then instructed all staff and maintained toolbox talks that when using extension cables, the maximum that all plug labels in the extension sockets should not exceed a total of 13, being the fuse rating of the plug in the extension lead.

Guys doing the PAT whould ensure that the number rating on the plug top was clear and legible.

Simple to understand and audit.

Originally Posted by: UncleFester

Originally Posted by: chris42

My question is, has anyone come up with a nice easy way to ensure that people don’t overload these extension leads?

How do you control their use?

Chris

In the past I've calculated the current taken by the item and written this numerically on the plug top - i.e. 1000W rated appliance / 230v = 5 rounded up. I've then instructed all staff and maintained toolbox talks that when using extension cables, the maximum that all plug labels in the extension sockets should not exceed a total of 13, being the fuse rating of the plug in the extension lead.

Guys doing the PAT whould ensure that the number rating on the plug top was clear and legible.

Simple to understand and audit.

Yes, that is what I was thinking unfortunately our PAT test person puts his sticker on the plug, So I was considering a little tag with the number on it attached to the wire near the plug (possibly colour coded to see at a glance).

Interesting idea about grouping Invictus, yes, we would not allow kettles in an office, but you would be surprised where they can be hidden. In a previous life, I once found a microwave, kettle and toaster in a metal filing cabinet on the workshop floor. Also, it is the other items such as little fan heaters that pop up from time to time (hate them) and who knows what else the little darlings may get their hands on. 

Cheers all

Chris