UK wiring advice - garage circuit - Page 1
Forum section: electronics / general

author: tom66
author_rank: Super Contributor
timestamp: November 04, 2019, 10:03:08 pm
content: I have just acquired a tumble dryer from a friend for the low price of zero. The mains fuse was blown. Easy fix.I want to put it in my garage, but the issue I have is that the garage, for some reason (cheap landlords, I suppose) is effectively wired into a 13 amp plug in the kitchen which is then connected to a 13A FCU with isolation switch.Inside the garage there is a simple consumer unit with a 16A circuit for the sockets (3 x double) and a 6A lighting circuit for the lamp. Seems that this part is done to code more or less.The problem is I've measured the current that the tumble dryer pulls and that is about 11A. I have a freezer in the garage, and a small 1kW electric heater. The electric heater is on a thermostat which triggers around 2'C to stop frost building up in the garage (as it is detached from my home).This creates a slight dilemma... I'd be okay with running the tumble dryer & heater & freezer off a 16A MCB as it is only a slight overload and it's likely that the heater will switch off as the dryer warms the garage. But I'd be less sure about the 13 amp fuse in the plug feeding this whole setup, not for potentially an hour or more while that fuse gets toasty. .Obviously if the fuse blows, the freezer will defrost and all my food will go bad, no good.So I would want to change the 13A socket and FCU for a more permanent arrangement but I don't want to put a whole new circuit in. I think I can wire this like a 16A fused spur but such a device does not exist, as far as I can tell.The question is then can I perhaps change this to an unfused spur and ensure that the garage is properly fused.Or can I fit some kind of 16A fused spur, despite such a mythical device not existing from my research?

author: Monkeh
author_rank: Super Contributor
timestamp: November 04, 2019, 10:08:58 pm
content: Quote from: tom66 on November 04, 2019, 10:03:08 pmAsk yourself why that fuse was blown, for a start..QuoteOkay, traditional fused spur, if a tad redundant. Common.QuoteWhich is a total waste - they could have just used another FCU for the lights. This is sort of beside the point, but educational..QuoteAnd here lies the rub. No, there's no compliant way to tap off for 16A here.If the garage is detached, extending the ring out to it is probably a pain. A dedicated circuit is really the only reasonable option.If it's attached, then rip that entire FCU and CU mess out and extend the ring - or, just put a dedicated circuit in, which is likely less effort.This is all assuming the source circuit is a 30A/32A ring final, which is likely. If it's a 16A or 20A radial, you're looking at too much loading, if it's a 32A radial then you would have to branch off in at least 4mm², but you could do so and get rid of that 13A limitation.

author: Monkeh
author_rank: Super Contributor
timestamp: November 04, 2019, 10:20:18 pm
content: I suppose I could point out that a 13A BS1362 will take 16A pretty much indefinitely, or until the carrier melts, whichever comes first. Please don't find out.

author: tom66
author_rank: Super Contributor
timestamp: November 05, 2019, 09:31:03 pm
content: Thanks.I have run the tumble dryer for some time. The fuse that was fitted was a no-name, so probably some inferior Chinese shit that couldn't take the load. The dryer doesn't seem to have any fault - gets warm, tumbles, even the interior lamp works perfectly.I've decided that I'll go for another option - I'll rig up some kind of unit will turn on the garage heater power if the dryer is not running. The dryer will be triggered by an electronic signal that virtually presses its on/off button. I'm building an electronic timer for the tumble dryer anyway as it does not have a timed start function, this will let me take advantage of Economy7 & lower CO2 electricity. This will all be run by an ESP8266 board and be wifi connected for ultimate smart home nonsense.In addition, I will remove the plug and 13A fuse and wire in the garage feed directly into the FCU - this will eliminate one fuse as a failure point.I'll also add a temperature probe to the freezer, which will give me some warning if the freezer isn't keeping temperature well (even if due to an internal breakdown.)

author: Monkeh
author_rank: Super Contributor
timestamp: November 05, 2019, 09:36:34 pm
content: Sounds like a plan.The whole plug and FCU thing is a screaming WTFmonster, so that'll be nice to get rid of. I'm hoping there's no ugly bodges with flex going on round there.

author: m3vuv
author_rank: Super Contributor
timestamp: December 02, 2019, 03:38:03 am
content: doesent part p regs come into play here?

author: Monkeh
author_rank: Super Contributor
timestamp: December 02, 2019, 05:00:31 am
content: Quote from: m3vuv on December 02, 2019, 03:38:03 amIn a word, no.