circuit-breaker allegedly "getting more sensitive"

Single phase supply? Let us know how you get on.

Regards, UKPN

breaker thresholds certainly creep when in  warm box pre-heated by neighbouring breakers. Indeed some of the more diligent breaker makers warn you of this.

I can imagine they might work loose if they are regularly "exercised" by overload. I suspect a lot of caravan users are a bit hazy with the details of exactly what it all consumes.

It might be quite telling to arrange some sort of din rail ammeter (there are now some very cheap ones out there that have a hole for a meter tail with the current clamp within, and then a couple of small terminals for voltage sense that can do reactive power too.)and perhaps also kWh style metering to show what demand is at dinner time accross site.

The real long term solution is a beefier supply, ideally 3 phase.

It might be time to try some Cable temperature indicators

Not exactly evidence, more just conjecture based on what is sometimes a simple remedy.  Typically these may be B type. Pitches are intermitantly overloaded now and again. With micowaves, plug in electric hob( to get value out of the hook up and save gas), then everything else, including the fan heater in the awning to keep the dog warm, enough of these on demand for a few seconds, is going to be 30 amps or more. Anecdotal, of course, but something that can alleviate the tripping issue, is to replace with a C type.

I have seen MCBs become more 'sensitive' over a period of time when loaded to near or at  their rating. At one time, some manufacturers (use to) recommend not loading MCBs beyond 2/3rds (two-thirds) of their marked rating.


I will post further if I can find the information in my files that are now in the loft.


Regards


Mike

Anecdotal, of course, but something that can alleviate the tripping issue, is to replace with a C type.

I was under the impression Alcomax that the thermal element of the circuit-breaker (CB) was the same irrespective of it being B, C or D and only the magnetic in-rush was different. The replacement of the CB with a C or D wouldn't alter the time of an overcurrent caused by too many heaters/kettles etc but would only help if say a tool transformer or welder were connected by not responding to the high inrush current.

Hi Persp, how are you involved?

The client heard about me (only the good bits I presume!) WB and decided that I might be able to come up with an alternative to the £15k he'd been quoted 15? and 10? years ago by WPD's predecessors for an increased supply of unknown kVA...........

Did the old breakers go in the general waste bin?

Not that I'm aware, but I'll try and retrieve them and bench test one of them with 10 A and then 16 A.

How heavily loaded is the electric bill compared with the bookings?

The units used last month equated to a steady state load of 5.2 kW and the meter is semi-intelligent and recorded a peak of 20.3 kW, presumably the maximum half-hour demand average for last month. I found 12 hook up points but need to check if any more hidden away............


From the 20.3 kW I'd say he's on a tightrope especially since not all pitches have access to a hook-up. He plans to extend to 50 pitches plus a shower block and wants me to use my crystal ball and reapply for a 3-ph supply,,,,,, I've yet to advise him about monthly availability charges once he's over 69 kVA or that he'll need and H-pole set up for a Tx over 100 kVA........ the crystal ball is still hazy but at least 120 kVA for 50 pitches plus stored hot water is likely to appear. Two spans of a third HV conductor also required. I'm thinking nearer £20k as the existing pole is only two years old, stout and double stayed so probably won't need renewing. I'll just have to have another meeting and give him some ideas.


He won't have bulk LPG on site even though there must be a quantity of smaller bottles in the caravans.... 


Previous experience of camp sites tells me that after this plan, he'll be looking at a visitor shop, laundry facilities, upgraded sewerage, more lights, manager's residential park home, it goes on..........


Regards


BOD

I will post further if I can find the information in my files that are now in the loft.


Thank you Mike. I'm sure others will find this "derating" of interest!


Regards


BOD

My design project for the City and Guilds 2400- Design, Erection and Verification was a camp site like this ?