billysheds
New member
Hi, I’ve been subscribing to this forum for a couple of years now. My background is, I was working in “Electrical Properties of Plastics” for, a well-known, multinational company. I did HTEC in Electronics and Electrical engineering. I have never done any installation, nor have any intention to do so. Please forgive me if my terminology is incorrect. Sorry for the lengthy thread but I thought you needed the detail
I volunteer at my local rugby club, doing general maintenance drawing the pitch lines etc. We recently managed to raise funds to have a pavilion/club house built. I did lots of the donkey work, plumbed in the bar and toilets etc.
The electrician who did the wiring on the new pavilion also rewired our existing shower block and changing rooms. We also had 2 Portacabins. One used for equipment storage the other our Tea Shack. The tea shack only had a 3kW urn for hot water and a 3kW water heater over the sink.
The incoming main feed is single phase PME going through an initial 100A fuse. It comes into a cabinet on the outside of the changing room block. It then goes into a second cabinet where it is split. The changing rooms are fed via 60A Kmf switch. The pavilion gets the other 40A.
There are two CUs in the home changing room (don’t trust the visitors!).
The 2 portacabins were fed from 40A MCBs, in one of the CUs, running through 4 core 16mm2 SWA. This runs out to a cabinet some 20M away. The cabinet splits the power to each of the portacabins. Each one again fed via 16mm2 SWA. The steel armour is connected to the earth bar in the main CU but not connected to the junction box. This has an earth rod which gave an earth loop impedance of 45Ω on a fairly dry day.
When the electrician finished his wiring and rewire he issued the relevant certificates and used the job as part of his evidence when he was inspected by his trade body (not sure which one). The portacabins were noted as not part of the job.
Now we come to my query… The Tea Shack has been replaced by a burger van which some of the guys have refurbished. It was also completely rewired by the daughter of one of the guys who is a newly qualified spark, and I believe signed off by her boss. All of the cooking is done on electrical appliances. The van has a small CU with 4 MCBs 2 are 32A for sockets. There is an earth rod for the burger van linked to the chassis as well.
One of the double sockets was reported as faulty. I agreed to do a like for like replacement and was supplied with an identical, new, double socket. When I looked at the existing one it had several cracks in the front. It was made by LAP which, I think, is a budget job from Screwfix. The “chef” also mentioned that the power trips at the MCB in the changing room main CU on a weekly basis. I’ve done the replacement with no trouble. My worry is they are overloading the system. The double socket in question has two 13A plugs in each feeding the two halves of their hotplate. Each half is 2.2kW. This is on from 08:00 till 14:00. I wondered if these low quality fittings should be changed to MK or some other make. I did even wonder if they should be fed via the type of sockets now made for EV supply, given their high draw for long periods. Though it would appear that if we use EV sockets they only come as singles and would need 1+1 gang back boxes.
I’ve now looked at their other appliances to see what their max draw could be (I was not involved in this project). They run :- Beer cooler, beer fridge, baked spuds oven, dual element hot plate, fridge, fridge/freezer, dual element fryer, microwave, water heater and toaster. Obviously not all at once. But I calculate their total load to be 18kW which I make to be 75A, assuming 240v. [BC1] Even allowing for diversity it seems way over, hence the tripping. The MCBs in the CU are Wylex B40. Could we ask the electrician to upgrade the MCB to a 50A or larger, The 16mm2 cable would carry that, I think?
When I was looking at the junction box for the burger van and portacabin I noticed that the SWA earth has been connected to the earth rod. I remember an electrician who fitted the earth rod (this was an off the cuff recommendation by the sparky who did the rewire) disconnecting this because we were an external building outside the equipotential of the changing room. I’m sure he measured the Earth Loop Impedance to be 45Ω, it was a dry day.
The other worrying occurrence was when we had a rugby 7s festival and the showers (4 x 2.2kW immersion heaters) and the burger van were running we blew the 60A fuse in the KMF switch and scorched it brown. The original installation electrician replaced the whole unit, but I’m sure the same could easily happen again.
So, long story short… Should we have the double sockets upgraded? Can we increase the MCB feeding the Van? Should the SWA earth be disconnected from the Earth rod? Are we pulling too much power? Should we try for another phase or any other options.
We will be getting an electrician in to do any work but since we have had conflicting advice from a couple of sources (one newbie, two very experienced) I thought I would ask your esteemed selves for advice.
[BC1]
I volunteer at my local rugby club, doing general maintenance drawing the pitch lines etc. We recently managed to raise funds to have a pavilion/club house built. I did lots of the donkey work, plumbed in the bar and toilets etc.
The electrician who did the wiring on the new pavilion also rewired our existing shower block and changing rooms. We also had 2 Portacabins. One used for equipment storage the other our Tea Shack. The tea shack only had a 3kW urn for hot water and a 3kW water heater over the sink.
The incoming main feed is single phase PME going through an initial 100A fuse. It comes into a cabinet on the outside of the changing room block. It then goes into a second cabinet where it is split. The changing rooms are fed via 60A Kmf switch. The pavilion gets the other 40A.
There are two CUs in the home changing room (don’t trust the visitors!).
The 2 portacabins were fed from 40A MCBs, in one of the CUs, running through 4 core 16mm2 SWA. This runs out to a cabinet some 20M away. The cabinet splits the power to each of the portacabins. Each one again fed via 16mm2 SWA. The steel armour is connected to the earth bar in the main CU but not connected to the junction box. This has an earth rod which gave an earth loop impedance of 45Ω on a fairly dry day.
When the electrician finished his wiring and rewire he issued the relevant certificates and used the job as part of his evidence when he was inspected by his trade body (not sure which one). The portacabins were noted as not part of the job.
Now we come to my query… The Tea Shack has been replaced by a burger van which some of the guys have refurbished. It was also completely rewired by the daughter of one of the guys who is a newly qualified spark, and I believe signed off by her boss. All of the cooking is done on electrical appliances. The van has a small CU with 4 MCBs 2 are 32A for sockets. There is an earth rod for the burger van linked to the chassis as well.
One of the double sockets was reported as faulty. I agreed to do a like for like replacement and was supplied with an identical, new, double socket. When I looked at the existing one it had several cracks in the front. It was made by LAP which, I think, is a budget job from Screwfix. The “chef” also mentioned that the power trips at the MCB in the changing room main CU on a weekly basis. I’ve done the replacement with no trouble. My worry is they are overloading the system. The double socket in question has two 13A plugs in each feeding the two halves of their hotplate. Each half is 2.2kW. This is on from 08:00 till 14:00. I wondered if these low quality fittings should be changed to MK or some other make. I did even wonder if they should be fed via the type of sockets now made for EV supply, given their high draw for long periods. Though it would appear that if we use EV sockets they only come as singles and would need 1+1 gang back boxes.
I’ve now looked at their other appliances to see what their max draw could be (I was not involved in this project). They run :- Beer cooler, beer fridge, baked spuds oven, dual element hot plate, fridge, fridge/freezer, dual element fryer, microwave, water heater and toaster. Obviously not all at once. But I calculate their total load to be 18kW which I make to be 75A, assuming 240v. [BC1] Even allowing for diversity it seems way over, hence the tripping. The MCBs in the CU are Wylex B40. Could we ask the electrician to upgrade the MCB to a 50A or larger, The 16mm2 cable would carry that, I think?
When I was looking at the junction box for the burger van and portacabin I noticed that the SWA earth has been connected to the earth rod. I remember an electrician who fitted the earth rod (this was an off the cuff recommendation by the sparky who did the rewire) disconnecting this because we were an external building outside the equipotential of the changing room. I’m sure he measured the Earth Loop Impedance to be 45Ω, it was a dry day.
The other worrying occurrence was when we had a rugby 7s festival and the showers (4 x 2.2kW immersion heaters) and the burger van were running we blew the 60A fuse in the KMF switch and scorched it brown. The original installation electrician replaced the whole unit, but I’m sure the same could easily happen again.
So, long story short… Should we have the double sockets upgraded? Can we increase the MCB feeding the Van? Should the SWA earth be disconnected from the Earth rod? Are we pulling too much power? Should we try for another phase or any other options.
We will be getting an electrician in to do any work but since we have had conflicting advice from a couple of sources (one newbie, two very experienced) I thought I would ask your esteemed selves for advice.
[BC1]
